100 101

This advice note describes the manufacture and use of hand-made clay tiles in the counties of Kent, Sussex and Surrey, and deals with the repair and maintenance of tiled roofs and tile-hung walls. It considers regional details specific to the traditions of roofing and tile-hanging in the south-east of England, and explains the use, where appropriate, of modern peg tiles and roofing underlays.

Contents1 Introduction

2 History

3 Characteristics

4 Repairs and re-tiling

5 New tiles

6 Construction and detailing

7 Oast taper tiles and vertical tile-hanging

8 Maintenance

9 References

10 Other advice

11 Glossary

PEG TILES IN SOUTH-EAST ENGLAND

REGIONAL ADVICE NOTE 1

THE SOCIETY FOR THE PROTECTION OF ANCIENT BUILDINGS In association with the Kent Local Authorities Conservation Officers GroupP

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The content of this pamphlet is offered in good faith but neither the author nor Society, KCOG or IHBC can accept responsibility arising from incorrect or incomplete information that may be included. The use of traditional materials may incur risks different to those associated with modern materials. Manufacturers’ and suppliers’ guidelines should always be followed. This document should be seen as a contribution to a continuing debate and we welcome comments.

Thanks for advice on the preparation of this paper are due to the members of the KCOG, the SPAB Technical Panel and SPAB Technical Secretary. In particular, generous help, information and criticism has been given by the following: Charlie Howe and Karl Terry, Kent master roofers; Clive Bowley, Ollie Chapman, Rose Harrild, Tony Phillips and Edward Sargent, all from Kent; Nick Antram and Francis Kelly of English Heritage; and Douglas Kent of the SPAB. Edited by Kit Wedd. Drawings by Ray Harrison. Designed and produced by Nichola Nixon. Printed by Pressworks, London. © Ray Harrison/SPAB 2009.

ISBN 978 1 898856 16 8

The publication of this advice note has been made possible by a donation to the SPAB from the south-east region of the Institute of Historic Building Conservation.

The Society for the Protection of Ancient Buildings

■ advises on all problems affecting old buildings, giving technical advice on their treatment and repair. Buildings ecclesiastical and secular, large and small, including barns, dovecotes and bridges, come within the scope of the Society.

■ investigates cases of buildings suffering from neglect or threatened by damaging treatment or with destruction, concentrating on buildings erected before 1714.

■ holds two courses each year on the repair of historic buildings for architects, surveyors and builders, as well as a range of courses for owners, builders and others.

■ administers Scholarships and Fellowships, which enable architectural, surveying and engineering students and craftsmen to study old buildings and their repair.

■ arranges public lectures on specific subjects dealing with old buildings.

■ publishes information on the care of old buildings, their features and fittings. A list of these publications may be obtained online or upon application. Other books on conservation are sold by mail order.

■ issues a highly praised, quarterly magazine and a list of historic buildings in need of repair that are for sale.

■ campaigns on specific issues such as farm buildings and VAT on repairs to listed buildings.

■ has a separate section devoted to the care of mills.

MembershipThe Society for the Protection of Ancient Buildings37 Spital Square London E1 6DY

Telephone 020 7377 1644info@spab.org.uk www.spab.org.uk

A charitable company limited by guaranteeregistered in England and WalesCompany No 5743962 Charity No 111 3753Scottish Charity No SC 039244 VAT No 577 4276 02

With the Kent Local Authorities Conservation

Officers Group

By Ray Harrison AADipl DiplCons (York) RegArch

MIHBC

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With the Kent Local Authorities Conservation Officers Group

102 1

1 Introduction

The name ‘peg tile’ applies to a plain clay tile suspended, loose, from the top edge of a tiling lath or batten so as to overlap two courses below. It is held in place by a small wooden peg (or latterly an aluminium ‘drop’), wedged into, or passed through, one (or sometimes both) of two holes in the head of the tile (Figure 1). This fixing method contrasts with that in which tiles are hooked onto the battens by integral ‘nibs’, small projections on the underside of the tile at its head.

Until the 19th century, plain clay peg tiles were the preferred roof covering for buildings throughout south-east England. The tiles continued to be hand-made from local clays into the first half of the 20th century, and are still being produced today. They are the characteristic roofing material of the Kent, Surrey and Sussex countryside and villages, and they dominate the roofscape of many of the region’s towns.

The region has its own particular version of the peg tile, the ‘Kent peg’, which is somewhat smaller than tiles found in other parts of the country. Pegs are thought to be survivors of a type of tile that was previously distributed over a much wider area, including London. On average, Kent peg tiles measure just 254 x 152 x 9–10mm (10 x 6 x 3/8 in) compared to 265 x 160 x 13mm (101/2 x 61/2 x 1/2 in) for the more widely distributed English plain clay peg tile.

A statute of 1477 confirmed the standard dimensions for flat tiles as 101/2 in by 61/4in (267 x 159mm), with a thickness of at least 5/8 in (16mm); ridge tiles or crests should be 131/2 in by 61/4 in (343 x 159mm), and gutter tiles 101/2in (267mm) long.1 These sizes remained in use for centuries: in the 1726 edition of his City and Country Purchaser, Neve mentioned the 1477 Act and standard tile size, noting that tile thickness should be ‘half an Inch and half a quarter [5/8 in] at the least’.2 He found small variations: some Sussex tiles were 10 x 63/4 x 5/8 in (254 x 171 x 16 mm), and some were only 91/2 x 53/4 x approximately 1/2 in (241 x 146 x 13mm). ‘Reclaimed’ peg tiles today may vary by 25mm or more in length and 13mm in width.

Roofs clad with peg tiles are visually prominent because they are steeply pitched, at between 42° and 50°. They therefore make a very important contribution to the

particular character of the historic landscape and townscapes of the south-east. The region also has its own characteristic tiling details: the laced valleys used in East Anglia, for instance, are not found in the south-east.

2 History

Clay roofing tiles have been made in south-east England almost without interruption since the Romans established tileries in Kent (Figures 2 and 3). By the mid-14th century, tile production had become particularly associated with the monasteries. According to Clifton-Taylor, ‘in the reign of Edward III the Benedictine monks of Battle Abbey were sponsoring the manufacture of tiles at Wye… while the Cistercian house at Boxley… had its own tileyard.’3 There was a very large tile industry at Tyler Hill outside Canterbury.

Most tiles in use in the south-east today are likely to date from the 18th, 19th and early 20th centuries. Because the best are very enduring, however, many roofs in the region may incorporate some earlier tiles. The re-use of peg tiles must always have been common practice, better-burned tiles, which lasted longest, being recycled most often. In the mid-19th century it was observed that, ‘As old tiles are of a much better consistency than those now made, it may be desirable to re-use the best of them with new tiles to fill in.’4 This is not the only record of problems with new tiles; a national investigation in the 15th century reported complaints about variations in size and quality: ‘It was said that many of the tiles then being produced would last only four or five years instead of forty or fifty.’5

Nib tiles never really caught on in the south-east. Neve took for granted the use of ‘Tyle pinns’ or pegs: ‘an Experienced Workman tells me, he uses but about a peck of Pins to three Square of Healing [roofing], which at seven Inch Gauge… is more than enough for 2000 Tyles.’6 By 1850, national practice was becoming standardised: ‘Plain tiles were formerly made with holes in them for the reception of the tile-pins, by which they were hung on the laths; but the common method is now to turn down a couple of nibs at the head of the tile, which answer the same purpose.’7 Even in the industrial age, however, there was room for variation, and in 1948 it was noted that plain tiles might be ‘with or without nibs (or cogs) at the back’.8

The making of tile pegs was a job for

Front cover: Peg-tiled

roofs in Tenterden, Kent,

seen from the tower of the

parish church: a roofscape

dominated by short roof

slopes spanning narrow

18th- and 19th-century

buildings. One wider,

higher, hipped roof denotes

a medieval house. (After

MacManus & Partners and

Cullen, G, 1967.)

1 Roof covering cut away to

show relation of tile pegs to

battens.

2 Maker’s stamp on the

back of a Kent peg tile,

probably 19th-century.

3 Detail of a seal on a deed

of 1272 from Otford, Kent.

The central chimney pot

is mortared onto the roof

slope, confirming hard,

probably clay, ‘tiles’.

(From Dunning, G C, 1961.)

Softwood tile peg next to

a modern tile nail, or ‘tile

drop’

1

32

Batten

Rafter

Tile peg

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winter, the builder’s off-season. Not all authorities agreed on the best timber for pegs. In 1916, Innocent quoting a source in south-west Surrey wrote that, ‘hazel or willow was used for the pins, but “the delight of the tiler was to get hold of an old elder stump, which was supposed to make the most durable pins of all.”’9 Recently, specialist suppliers have marketed oak pegs — but historic examples are often found to be made of softwood. Modern aluminium pegs should not be used where there is any possibility of their coming into contact with lime, which may cause corrosion.

3 Characteristics

Simple firing methods and local clays produced strong, durable and light peg tiles, many in the warm orange/red terracotta colour often regarded as typical of roofs in the south-east. In fact, colours ranging from pale orange/buff through orange to a darker red can be found across the region. Occasionally, buff/white tiles of a kind more common in East Anglia also occur. Not all colours are derived from the natural colour of the clay: a strong dark brown tinge is likely to be due to an accumulation of dirt on the tile surface, and it is noticeable that tiles in the country tend to stay brighter than those in towns.

Historic peg tiles have a smooth surface, because any sand that was attached to the surface in the moulding process has weathered away. A common feature is the ‘smile’, the curved ‘creasing’ in the surface near the foot of the tile, which is due to the hand-moulding process (Figure 4).

Although superficially rustic in character, the peg-tiled roof is a sophisticated structure in which form and function combine to produce a distinctive appearance. Hand-manufacture, ‘primitive’ firing and occasional imperfections in the prepared raw material mean that no two tiles are identical. They do not bed down regularly onto the battens or each other. They catch the light at different angles, and their small size enhances these effects. Such variations give the roof surface a continually changing appearance, depending on the angle from which it is viewed. The result is roofscapes of great visual richness that are never tiring to the eye (Figure 5).

Historic peg-tiled roofs also derive their individual character from the number of re-tilings that the building has undergone.

At each full re-tiling a percentage of failed tiles from the original batch will be replaced by new ones made to roughly the same size but with subtle differences in other aspects of their appearance. Early surviving tiles are often double-cambered (Figure 6), a little smaller than later tiles and very rough in surface texture. Victorian peg tiles are frequently smoother and more or less flat. They are also bigger; there may be a difference of as much as 25mm in length and up to 13mm in width. Minor variations in colour and texture are introduced within a single roof over time, producing an exceptional beauty that is impossible to achieve with ‘instant’ materials and methods.

There are functional advantages to the ‘imperfect’ nature of the Kent peg tile. Plain, machine-made flat tiles will draw water up by capillary action between their overlying surfaces; this water may enter the roof space or, in winter, freeze between tiles, causing frost damage. The air pockets formed between the irregular surfaces of Kent peg tiles, however, impede capillarity so that water is not so easily drawn up. Moreover, in construction where roofing underlay was unknown, these air pockets formed airways between inside and outside, making the interior of the roof self-ventilating. (See also Section 5.3.)

4 Repairs and re-tiling

Even when tiles are in good condition, peg-tiled roofs may develop problems if their fixings or supporting timbers deteriorate. Metal nails used to fix laths and battens to the rafters may corrode; battens and laths can then fail, causing tiles to slip. Insect or fungal attack may cause battens and laths to decay. Tiles may deteriorate due to frost action, especially on north-facing slopes where moss may exacerbate the effect of the freeze/thaw cycle. Mechanical damage may also be caused by wind-lift and the decay of mortar ‘torching’ underneath tiles.

Several principles should be followed when considering roof work:■ The decision to repair or fully re-tile

depends on the extent of deterioration. If laths or battens are sound and tile slippage is on a small scale, this might be dealt with as routine maintenance (see Section 8). Re-tiling should only be considered when repairs are no longer cost-effective.

■ The condition of gutters and flashings

4 Hand-made Kent peg tile,

showing tile crease or ‘smile’

in the tail.

5 Hip tiled with old Kent

pegs. Note a slight upcurve

in tiling to each side of

the 19th-century cast iron

rooflight, which is set low

into the roof slope, allowing

the tiling to remain the

dominant feature of the roof.

6 Modern cambered plain

tiles, designed so that only

their tails are in contact with

the tile below, making an air

gap:

(a) single-cambered

(b) double-cambered.

Alternative hip peak and its underlying structure

Tile ‘tail’

Tile ‘head’

4

5

6(a) 6(b)

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also influences the course of action. A roof stripped for re-tiling provides an opportunity to carry out any necessary repairs to the supporting structure, along with other associated work (for example, to gutters or chimney stacks).

■ Unless the stability or watertightness of an uneven roof is causing concern, no attempt should be made to straighten it up just to create a level surface. Where the stability of a roof is in doubt, a suitably qualified structural engineer should be consulted.

■ In stripping a roof, care should be taken to avoid breakages when removing tiles, so as to preserve as many as possible for re-use. Depending on circumstances, new tiles might be mixed with old ones across the roof, or reserved for the least prominent roof slopes.

■ The emphasis should be on matching details appropriate to the locality and the age of the building. The existing roof covering and support structure should be recorded in notes and photographs both before the tiles are disturbed and during their stripping. Some general advice on detailing is given in Section 6.

■ Occasionally, it is acceptable to introduce modifications. Alterations might be justified, for example, to improve access for maintenance. Changing details of a roof on a listed building may require statutory consent.

■ The use of spray-on coatings underneath roofs, or bitumen-coated fabric on top, is inadvisable. Such treatments prevent proper inspection, hinder the re-use of tiles and, by reducing ventilation, increase the risk of timber decay.

■ The SPAB or local authority conservation officer may be able to advise on suitably-qualified professionals or roofers in your area who can inspect or work on a roof.

■ Checks should be made early in the planning stage of the work, to see whether bats are present. If they are found, seek advice from the appropriate statutory national conservation organisation (see Section 10.2). It is illegal to harm or disturb bats or their roosts without permission.

■ Always take care of your own safety and that of others when working at height.

5 New tiles

5.1 Re-use and theft

In the past local manufacturers supplied all the tiles used on roofs in the south-east. Those historic tiles that have survived are now a finite, irreplaceable resource and there is a strong market in second-hand peg tiles. Demand for recycled peg tiles has been driven by local authorities’ expectations that like-for-like materials will be used for repairs, and by the public’s growing appreciation of the tiles’ aesthetic value.

One unfortunate result of this is the steady erosion of the character of the region’s historic environment, as peg tiles are removed from existing buildings to supply materials for repairs, new roofs or the replacement of corrugated sheet roofs on barn conversions (Figure 7). For the thief, tiles are easy to remove unless they are nailed to the battens every few courses or have lime mortar torching below. Security-marking tiles with an anti-theft chemical can also help deter thieves. It is now acknowledged that second-hand peg tiles offered for sale today, are likely to have been acquired (legitimately or not) by the partial or total destruction of an irreplaceable historic roof, which probably made a unique contribution to the historic character of its setting. Ideally, therefore, reclaimed tiles should only be used on the building or group of buildings from which they were removed. Local authorities, along with other building conservation bodies, now often encourage the use of new peg tiles both for repair and ‘new build’.

5.2 New peg tiles

Several companies in south-east England are now producing what they describe as hand-made peg tiles, which can make good substitutes for historic tiles, both functionally and in appearance (Figure 8). Some new tiles are a little larger than Kent peg tiles, but can still be suitable for entirely new work in certain situations.

In modern building programmes, ‘lead-in’ times for supply of materials are crucial. The supplier and type of tile must be confirmed at the earliest possible stage if compromises over obtaining the right tile for the job are to be avoided. When ordering tiles it should be remembered that not only colour and texture, but size also, may vary between manufacturers.

8

7

7 Russet-coloured clay

tiling over black tarred

weatherboarding made a

classic landscape element

out of this small agricultural

building in the corner of a

field. The tiles can be worth

more to the owner than the

structure itself, if the building

is not a candidate for ‘change

of use’ under the planning

regulations.

8 ‘Hand-made’ plain clay

tiles, some second-hand and

others new. In the centre

are two nib tiles; the rest are

peg tiles. At the bottom is a

(smaller) Kent peg tile.

9 Modern peg tiles showing

a regularised appearance:

(a) consistent camber

(b) flatness, lacking camber.

9(a)

9(b)

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5.3 The manufacture of modern peg tiles

Peg tiles were formerly made from unmilled clay containing stones or clay pellets that could create inconsistencies in the tile surface. Tile clay is now mechanically milled to make it smooth, which creates a more reliable product with insignificant loss of character.

Truly hand-made tiles are produced by throwing a lump of soft clay into a mould and scraping off the surplus from the top of the mould using a ‘strike’. This process pushes the clay to the end of the tile, producing the ‘smile’ shown in Figure 4. In semi-mechanised production, the prepared clay is extruded under pressure and cut into slabs, which are placed and pressed into the mould by hand, producing no ‘smile’. Tiles made in this way are often denser than the originals and may also look a little more even.

Lightly sanding the mould before each use prevents the clay from sticking to the mould, allowing the easy release of the newly formed wet tile. Some sand adheres to the face of the tile and is burned onto it in firing. This ‘sand-face’ makes modern peg tiles appear slightly different close-up from historic tiles; on the latter the sand has usually been weathered away, leaving a smooth surface.

Modern Kent peg tiles can be single- or double-cambered (see Section 3). This not only prevents water being drawn up between the tiles and improves ventilation in unfelted roofs, but also facilitates the bedding of tiles on the roof, since only the end of the upper tile rests on the tile below. In some modern tiles, a combination of regular camber with standardised dimensions and peg-hole positioning introduces a consistent appearance of rise and fall within each course, which is subtly different from the random course-line effect of the historic tile (Figure 9(a)). This regularity is strengthened by the use of dead straight modern sawn battens to support each course of tiling. The visually monotonous appearance of an alternative, almost flat, type of modern tile is shown in Figure 9(b).

5.4 The colour of modern peg tiles

Tile colour depends upon the type of raw clay used, whether or not anything is added to the basic clay mix before firing or to the surface of the product before or during firing, and the temperature at which the material is ‘burnt’.

Peg tiles made from local Wealden clay have the familiar orange colour varying through to dark red. Several manufacturers, however, use Etruria Marl from the Midlands, which produces a dense tile with a blue-brown through-colour. In order to match the colour of Kent peg tiles, Etruria Marl tiles are modified during production using surface dyes. Confusingly, the surface of some of the tiles made from Wealden clays is also coloured with dye so that the manufacturer can offer a range of standard colours, from light to dark, to meet a market that demands consistency in colour choice. Direct comparison usually shows up the difference between through- and surface-coloured tiles.

Newly-laid Wealden clay tiles can appear quite bright. This brightness eventually wears off and the new can then come to match the old pretty well. Because the choice of new tile is often made on the basis of its initial, rather than its weathered appearance, manufacturers have to offer the option of ‘pre-weathered’, darker colours. It should be remembered, however, that when, say, patching an old roof using new tiles, matching the new to an existing dark tile colour does not necessarily mean that there will be a long-term match. With weathering, the darker end of the modern colour ranges tends to become duller and darker still over time.10 The lighter colours generally give the best long-term effect on the roof. Dark (or light) tiles scattered through a roof of much lighter (or darker) tiles produce a particularly unpleasant, speckled, effect, which is to be avoided.

6 Construction and detailing

6.1 Fixings, laths/battens and torching

In historic construction, peg tiles were not nailed unless there was a problem with exposure to high wind. While this remains established local roofing practice today, some modern specifications frequently call for nailing at every fifth course. Two square peg holes, never exactly aligned, were hand-punched through each tile before firing. The roofer, tiling to riven hardwood laths that lacked the regularity of later straight sawn battens, could thus choose the more convenient peg hole and use only one peg per tile. A choice of alternative peg holes also allows a little adjustment between adjacent tiles, which are seldom exactly the same size.

10 Tile measurements:

(a) Kent pegs at same scale to

show varying tile sizes and hole

positions

(b) lap and gauge.

11 Roof without underlay

showing ridge and tilting

fillet with part-view of roof

underside to show effect of

battens and tile pegs. (After

Jaggard, W R and Drury, F E,

1949.)

10(a) 10(b)

Gauge

Lap

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11

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Detail of haired lime mortar

torching to tile underside

Lath

Alternative, early-18th-century

eaves detail with brick tilting fillet,

recorded in east Kent

‘Oversail’ brick

course forms tilting

fillet

Brick walling

Window frame

Window lintel

Wallplate

Roof truss

Ridge

Part-view of

underside of

roof

Rafter

Wallplate

Eaves

Masonry

walling

8 9

In most modern peg tiles, the holes are jig-formed, and pegged to sawn laths of regular dimensions. Kent peg tile gauge today is between 90 and 100mm (Figure 10).

Where a roof underside is open to view, it is preferable to use wooden pegs rather than metal drops and, if appropriate, torching. Mortar torching was often applied underneath tiles to improve the weather resistance of the roof.11 It also helped to keep the pegs in place. Basic (‘single’) torching is shown in Figure 11. It is preferable to retain all existing historic details, including torching, which remains a successful and appropriate technique if carried out correctly.

Horizontal lengths of timber lath or batten are nailed to the rafters of the roof in the usual way to support each course of tiles. Neve commented, ‘There are three kinds of Laths, viz. Heart of Oak, Sap-laths, and Deal-laths; the two last Sorts are us’d for Ceiling and Partitioning, and the first for Tyling only.’12 The earlier form is the riven oak or chestnut lath and this is still found occasionally on old roofs and as backing to historic tile-hanging on walls. Laths, usually in lengths from 900–1800mm, are split, or ‘riven’, out of larger timber and their cross-section therefore follows the natural contour of the grain. Riven hardwood tiling laths on historic buildings in Kent average 25mm wide by at least 6mm thick.

Softwood battens are sawn, and need to be greater in cross-section than riven laths to achieve similar strength. Their use with plain tiling may initially have arisen out of their employment with thin Welsh slating, which is always nailed to the battens. Modern battens are up to 32mm wide by 19–25mm thick. The increased depth has the benefit of preventing the tile peg from penetrating modern roofing underlay (where this is required), which is laid above the rafters and beneath the battens. In the recent past, the recommended size for softwood battens was larger: 51 x 19–25mm for a span of 305mm between rafters.13 Sawn hardwood battens are also available today.

The almost universal use of the modern batten with peg tiles today gives a more uniform, and therefore less visually lively, character to the tiling than was obtained with riven laths. The latter are now available again through specialist suppliers, should the historically accurate, more uneven and therefore more visually interesting type of tiling be desired. In Building Craftsmanship, published in 1929, Lloyd suggested that the spacing of riven lathing should be deliberately

These recommendations are preferred options. Should the alternative of second-

hand tiles be offered, local authorities have no legal grounds for opposing their

use. However, if there is any concern about the source of second-hand tiles, it

would be reasonable for a local authority to request convincing evidence of where

they have come from.

(a) Re-tiling and patching existing peg-tiled roofs on listed buildings,

unlisted buildings in conservation areas and unlisted buildings for ‘change

of use’

The use of new peg tiles, mixed, if necessary and appropriate, with any existing

historic tiles, is to be encouraged. In the case of local authority grant-aided works,

the use of new tiles should generally be encouraged.

Justification: To encourage local manufacture of new tiles and support the

retention of historic peg tiles on other buildings that already contribute to the

character of the area.

(b) New tiled roofs on extensions to peg-tiled listed buildings or to unlisted

buildings in conservation areas

The use of new peg tiles should generally be encouraged by the local authority.

Justification: As above.

(c) Stripping and re-covering the roofs of listed and unlisted buildings,

including redundant agricultural buildings that are subject to change-of-use

proposals (eg to residential), that are at present roofed with sheet material

In many cases sheet material has replaced thatch. Where this is clearly the

case, the local authority should generally require that the thatch be reinstated

as a condition of approval. Where the applicant can show that the original roof

was peg-tiled, the local authority should generally encourage reinstatement in

appropriate new tiles.

Justification: To ensure that the appropriate original roof finish, whether thatch or

peg tiles, is reinstated on buildings contributing to the character of the region; to

encourage local manufacture of new tiles and support the retention of historic peg

tiles on other buildings that already contribute to the character of the area.

(d) New buildings in historic contexts

Where the local authority seeks, or agrees to, the use of peg tiles, it will

encourage the use of an appropriate new tile, either a Kent peg tile or the slightly

larger ‘standard’ peg tile, rather than a second-hand one.

Justification: To encourage local manufacture of new tiles and support the

retention of historic peg tiles on other buildings that already contribute to the

character of the area.

Circumstances in which the use of new peg tiles should be considered 12 Ridges. The typical

hogsback ridge is tilted up

slightly from the horizontal at

its end:

(a) on the hip, the end ridge tile

lies over the top two bonnet

hips and must tilt to master

them (after Keymer Tile Ltd)

(b) at the verge, the tilt is due

to the uptilt of the plain tiles as

they approach the edge of the

roof

(c) and (d) fancy and British

Standard ridges from a

National Clayware Federation

list of the 1950/60s

(e) ‘crested’ ridges and a

terracotta vent.

13 Ridge, bonnet and valley

tiles:

(a) key components of a

peg-tiled roof – plain peg tile,

bonnet hip tile nailed once at its

head and with its tail bedded

in lime mortar where it rests

on the head of the bonnet

below, valley tile without nail

holes, laid dry and with its tail

overlapping the head of the

tile below, hogsback ridge not

nailed, with its sides set in lime

mortar, and mortar-jointed to

its neighbour

(b) old hogsback ridge tiles on

an equivalent hip in Faversham,

Kent.

12(a)

12(b)

12(e)

13(a)

13(b)

Bonnet tiles on

a hip with a tiled

valley abutting

the chimney

stack

Tilt up

12(c) 12(d)

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(e)/

Nat

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(d)

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End view of

ridge over

bonnet tiles

10 11

junctions (Figure 15). Lead flashings can also be found on the hips of buildings where abutting roof planes do not meet at right angles (as an alternative to the half-round ridge tile). It is important to perpetuate such historic elements when re-roofing takes place.

Valleys in peg-tiled roofs are invariably managed by the use of another standard ‘special’, the valley tile. This tapered tile, like the bonnet, is laid-in with the tile coursing to give visual continuity round the corner, but with its wider end towards the top rather than the bottom (Figure 13(a)). Valley tiles are not pegged-in but hold their position by gravity. ‘Secret’ or lead valley gutters are unnecessary, and were therefore unknown, with peg tile roofs.

6.3 Verges and abutments

Verges, with and without undercloaks, are found within the peg tile tradition, and examples of both are shown in Figure 16.

It was customary to finish courses of tiles with alternate full and cut half-tiles at verges and abutments, carrying the roof’s overall joint pattern right to the edge of the gable or stack. Today, tile-and-a-half specials are provided, doing away with the cut tiles (Figure 17); however, these can introduce an alien and visually jarring element. The appearance of the new tile-and-a-half is particularly unfortunate when introduced into roofing of re-used historic tiles. Although it is claimed that the tile-and-a-half is less vulnerable to wind damage than the cut tile, the latter can be perfectly secure if fitted by a competent tiler and well bedded in (cement-free) lime mortar.

The slight uptilt of the tiles at the verge of a peg-tiled roof (Figure 18) is designed to direct water flowing down the roof slope away from the edge and back down over the tiling. It causes the raising of the end of the ridge tiles as they approach the verge (Figure 12(b)). Carrying the lath/batten up onto the edge of the undercloak to obtain the upward tilt is shown in the 1949 edition of Jaggard and Drury.16 Depending on circumstances, tilers today sometimes finish the batten at the edge of the undercloak tile, achieving the tilt solely in the thickening of the mortar joint between undercloak and verge roof tiles (Figure 18(b)).

Many a roofscape has been blemished by the inappropriate use of lead flashings around chimneys and at other abutments; Lloyd discusses eyesore flashings in Building Craftsmanship.17 Abutments to peg-tiled

varied, to enhance the uneven effect.14

6.2 Ridges, hips and valleys

Ridges on medieval clay-tiled roofs could be quite elaborate, and various forms of crested ridge used in the 19th century, especially on church roofs, suggest medieval precedents. For the last 500 years, however, the favoured ridge form for roofs in Britain has been the hogsback (Figure 12). The Kent ridge tile is 300mm (12in) long, compared to 350mm (14in) in the modern British Standard clay ridge. The standard ridge length in 1477 was 343mm (131/2in), which perhaps reflects the widespread general use of the larger tile at that date.

Like the hogsback, the half-round ridge used outside south-east England to cap the hips of plain-tiled roofs rules a strong line down each angle of the roof, visually separating slope from slope (Figure 13(b)). Within the South-east, however, a special tile, known now as the ‘bonnet hip’, was used (Figures 12 and 13(a)). Well-laid and appropriately-sized upcurving bonnet hips carry the line of the horizontal tile coursing around the hip corner without a break, creating visual continuity between adjacent slopes. The seeming inevitability of the arrangement, noticeably different in appearance to the hip formed in half-round ridge tiles, is typical of post-medieval vernacular building detail as it developed in south-east England. Neve calls this form the ‘Hip or Corner’ tile. He also gives clear descriptions of the ‘Ridge, Roof or Crease’ tile, the ‘Gutter’ or valley tile and a Sussex speciality, the ‘Dormar or Dorman’ tile, which appears to have been a type of abutment flashing tile.15 Bonnet hip tiles were produced with different curvatures to cater for different roof slopes. For the correct ‘seamless’ effect the tiles in the courses abutting the bonnet must have their edges cut to the line of its sides where these flare down and out to meet them. Figure 14 illustrates examples of well- and badly-fitting bonnets.

Bedding mortar for ridge and hip tiles should normally be lime-based (without cement).

Occasionally, peg-tiled roofs have their hips and ridge formed in substantial lead flashings, which ‘frame’ each tile-covered slope. This arrangement seems to have been particularly popular in the first half of the 18th century. It involves projecting the tops of the ridge board and hip rafters well above the level of the common rafters to form an upstand in the lead cover flashings at these

14 Bonnet tiles:

(a) modern example of bonnet

hips poorly adjusted to the roof

pitch, giving an angular junction

with the roof surface

(b) old, slightly dilapidated roof

where the bonnet hips sweep

down naturally to meet the

tiles. The tiler has had some

difficulties at the junction

between tiles and hips. Modern

equipment makes it easier

to angle-cut tiles for such

junctions.

15 Heavy lead ridge flashing

on an early 18th-century

house in east Kent.

Detail

14(b)

14(a)

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16 Verge details. Tiles

always overhang the gable

edge:

(a) tile battens projecting

out beyond the wall face to

support the tile overhang, with

the gaps between each tile

carefully pointed-up (probably

an archaic detail); (b) and (c)

without support from below, the

overhang can only be a narrow

one. Common practice today

is to bed a flat, butt-jointed

course of tiles on top of the

gable, projecting slightly over

the edge. The gap between

these undercloak tiles and

those forming the roof surface

is pointed up in mortar; (b) has

clay tiles as an undercloak, with

a tight and well-finished mortar

joint between the two sets of

tiles; (c) shows inferior work

using thin, artificial material

such as fibre-cement board,

and mortar that is too thick and

visually ‘heavy’.

16(a) 16(b)

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16(c)

16(d)

16(e)

18 Uptilt of tiles:

(a) tiling raised up slightly at the

edge of the building by carrying

the tile laths/battens onto the

edge of the tile undercloak

course, which lifts them slightly

(b) the tilt formed by mortar

bedding alone

(c) the effect of the tile-and-

a-half verge. The extreme end

uptilt of the ridge is unusual,

but it shows how the tilt of the

verge is inevitably echoed in

the ridge

(d) cross-section through

the side of a rooflight: the

edge of the rooflight acts as

an undercloak, with mortar

pointing as for a verge.

Batten

18(a) 18(b)

18(c)

18(d)

17

Details

comparing the

use of half tiles

and the larger

tile-and-a-half

Lath

Cross-section

RooflightBattenMortar

Rafter

Half tile

Full tile

Mortar

Undercloak tile

Half tile

Full tile

Mortar

Undercloak tile

17 Part of a roof slope

showing verge to gable

formed in tile-and-a-half

alternated with standard tile

widths.

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19 Tile fillet:

(a) laid around a chimney stack

(b) up the inside of a Dutch

gable.

20 Principal of the standard

eaves ‘tilting fillet’ – a

tapered board running along

the edge of the rafters above

the gutter to raise the eaves

tiles flush with the roof plane.

21 Eaves:

(a) medieval hip with a very

apparent roof ‘flare’ towards

the bottom

(b) and (c) historic Kent

sprocketing, timber frame and

brick wall heads

(d) contrasting modern

sprocketing to a masonry wall

(after Jaggard, W R and Drury,

F E, 1949).

19(a) 19(b)

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21(c) 21(d)

Rafter

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Internal

sprocket

Sprocket

Sprocket

21(b)

Sprocket

21(a)

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20

Wall

Wallplate

BattenDouble tile

thickness

Timber

tilting fillet

22 Roofing underlay:

(a) in cold roof construction

(b) with a piece of batten fixed

between laps to form a vent.

23 Roof ventilation at eaves:

(a) boxed eaves. Unobtrusive

ventilation slots can be made at

the sides of the box soffit

(b) exposed rafter ends. In

historic roofs, there is usually a

gap between wall plate and tile

battens, providing an airway

(c) corbelled brick eaves with

timber tilting fillet. It may

be possible to substitute a

proprietary vent system for this

(d) corbelled brick eaves where

brickwork forms the tilting fillet.

Counter-battening (Figure 24)

may be the only solution.

22(a)

23(a) 23(b)

22(b)

23(c) 23(d)

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16 17

order to provide secondary protection from wind-driven snow and rain. This also allows work to proceed during bad weather. The use of an underlay beneath the tiles may be unnecessary, however, particularly where a roof has performed satisfactorily for many years without it. Underlay is also unsuitable where the appearance of the roof underside is important. Here, riven laths rather than sawn battens will normally be appropriate, and torching should be used if already existing.

Modern underlays come in various forms (reinforced felt, breather membranes etc). It is essential to ensure that their use will not set up condensation problems that could lead to premature decay of the roof structure. To this end, manufacturers’ instructions – particularly any requirement to seal penetrations into a roof void to limit the ingress of water vapour – should be followed closely. It should also be borne in mind that vapour permeable membranes are not ‘time-tested’.

Underlay is allowed to sag slightly between rafters where there is no counter-battening, to drain any water away to the eaves (Figure 22(a)). Eaves details can often be modified without much damaging their historic character (Figure 23). Where additional ventilation is required beneath an underlay, this can be obtained by gaps between overlapping sections of felt (Figure 22(b)) and/or eaves-to-eaves air-paths through the roof space (Figure 23), with the eaves vents meshed internally to prevent insect entry. A narrow run of felt is also sometimes omitted on each side of the ridge, to allow rising heat and moisture vapour to escape between the tiles.

As with roof coverings, the insertion of a membrane behind vertical claddings should be carefully justified rather than used by default.

Changes to the external appearance of existing roofs can arise through pressure to meet Government targets for the reduction of heat loss through the roof by the introduction of modern loft insulating systems. Unfortunately, however, the fixing of modern insulating materials within the depth of, or immediately on top of, rafters, can have a serious effect on the character of a roof. It may involve counter-battening – the use of one or sometimes even two – extra layers of battens on top of the rafters and beneath the tiles, often with visually-damaging consequences. The effect of counter-battening, or other thickening of the roof depth above the rafters, is particularly noticeable at verges and eaves

roofs were not flashed with lead as was the case with slate roofs: instead, the junction was cloaked by tile fillets laid in lime mortar; a detail that is perfectly serviceable if properly carried out (Figure 19). Nevertheless, when renewing fillets, it may be prudent to include concealed lead soakers as additional protection against moisture ingress.

6.4 Eaves and gambrels

Tile undercloaking at eaves was, and remains, standard practice (Figure 20). It is most visible only as a double tile thickness along the length of the eaves, above the gutter. A timber tilting fillet is often used to raise the tails of these lowest tiles to the same pitch as the rest of the tiling.

On some roofs a slight change in pitch occurs towards the eaves, achieved by fixing ‘sprocket pieces’ to the eaves end of the rafters (Figure 21). This attractive ‘flare’ is likely to have originated before the use of gutters became common, as a means of extending the eaves of steeply-pitched tiled roofs outward, thereby throwing water away from the wall face below. Used with gutters, it slows the flow of rainwater as it approaches the drop into the gutter, and reduces splashing.

At the change in angle between the two slopes on a gambrel roof, a special tile, bent in the middle to accommodate both the upper and the lower roof pitches, is sometimes used. More usually, the slope change is managed by a continuous lead flashing.

6.5 Roof ventilation, underlays and insulation

The gaps between the tiles of a conventionally-laid ‘peg’ roof provide airways by which convection and other air currents carry moisture-laden air from inside the building to the outside. Wind blowing over and across a roof creates a partial vacuum on the outside of the downwind slope, which helps draw air out via the tile gaps – the draught comes in at one side and out the other, and this also helps to remove warm, damp air from the roof space. The danger to building fabric from wet, and other, rot, exacerbated when moisture condenses within a sealed-in roof space, is therefore avoided.

Whereas torching was widely used in the past (see Section 6.1), today a thin flexible sheet of underlay, unknown to the old builders, is almost invariably laid over the rafters and beneath the battens in

24 Effect of counter-

battening on appearance of

eaves – sections contrasted

to show effects before and

after counter-battening:

(a) sprocketed eaves. Counter-

battens can be run out at the

sprockets with little effect on

eaves character

(b) exposed rafter end eaves.

Counter-batten increases depth

of tilting fillet

(c) corbelled brick eaves with

inset rafter end. Counter-batten

requires introduction of tilting

fillet

(d) boxed eaves. Counter-

batten increases depth of

fascia board.

24(a)

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Batten

Counter-batten

on top of each

rafter

Underlay on

raftersRafter

24(b) 24(d)24(c)

Eaves depth

increased

Counter-

batten

Counter-

batten

Counter-

batten

Fascia

18 19

(Figures 24 and 25).Because of their small scale, dormers

are particularly susceptible to visual damage from counter-battening and the like. The general rule should be, wherever possible, to avoid thickening-up the roof plane above the rafters in existing historic peg-tiled roofs. If it is considered that this cannot be avoided, the local planning authority should be asked at the earliest opportunity for informal guidance on the most acceptable way to balance energy efficiency with the preservation of historic character and appearance. This is particularly the case where consent for change of use of a building has been granted because of its architectural/historical value, or where a building is listed.

7 Oast taper tiles and vertical tile-hanging

7.1 Oast taper tiles

The steep, conical roofs of round oast house chambers needed special tiles. Oast tapers, or ‘reducer’ tiles, are tapered on two sides, to accommodate the reducing curvature of the chamber roof (Figure 26). They bring the satisfying peg tile appearance to the agricultural/industrial structures that are such an important feature of the regional historic building stock. A special rectangular corner tile was developed for the hips, or rather tapering corners, of square oast chambers.

7.2 Vertical tile-hanging

Peg tiles have long been used as an external wall covering over timber framing. In this case, they are invariably fixed either to laths or ‘ashlar’ boarding (sheathing) attached to the timber frame of the building. Neve called this type of tiling ‘Weather-tyling’.18 Sometimes the tile joints are pointed in lime mortar (Figure 27). Clifton-Taylor observed that,

‘Because these tiles hang vertically, rainwater runs off them at once, and unlike roof-tiles they do not remain damp for days … Lichens, mosses, seeds and soot particles do not therefore adhere to wall-tiles as they often do to pitched roofs, and for this reason they seem to be able to hold their richly glowing reds to an incomparable degree.’19

Another 20th-century authority noted that walls were often hung with ‘seconds’ that were not considered good enough to use on roofs, and that ‘buckled tiles can give an

interesting, uneven surface, and over-porous [ie underburnt] tiles, which are generally of a bright colour, can make a pleasing contrast’.20

Formerly, peg tiles used as wall cladding were, in east Kent at least, often fixed at a gauge of 150mm. Therefore 50mm of the vertical joint between each tile was not closed by a tile lap behind (Figure 28). In this case, a bedding of haired lime mortar, applied to horizontal riven hardwood lathing on the face of the studs as a backing to the tiles, was essential. The tile pegs were driven through between the laths, which were spaced closely enough to grip them as they were forced in. The lime mortar bed soaked up, and then exhaled, any residual water getting through the tiling at the overlap gap. It also prevented the tiles from ‘chattering’ in the wind.

Alternative practice retained the backing mortar but reduced the gauge to between 100 and 112mm to ensure that rain could not penetrate. Examples of both arrangements can still be found. Modern tile-hanging maintains the reduced gauge but does away with the mortar and slightly uneven lathing, replacing the latter with more regular softwood battens. The reduction in gauge subtly changes the tiling’s visual scale and aesthetic effect by increasing the number of shadow lines on the façade formed by the tile overlaps. As with weatherboards, the wider setting-out gives the more visually generous effect.

In the past, there has been an aesthetic prejudice against mortar-jointed tile-hanging21 but today, where it survives (and it is becoming progressively rarer) it is considered a significant and historically valuable feature of the old tradition. In recent years, tile-hanging direct to brickwork or concrete blocks has become popular, but this was rarely done before the 20th century, except as a remedy for leaking walls.

When turning tile-hanging around a corner there are three possible arrangements (Figures 29 and 30): a special corner tile; mitring (or simply butt-jointing) courses at the corner ; or the use of a vertical timber cover batten (‘fillet’ or ‘bead’). The purpose-made corner tile may be a historically recent invention, perhaps dating from the late 19th century, and looks completely out of place on a building, or in a context, earlier than this.

The corner cover batten is, in fact, a classic feature of the historic tile-hung building. It is usually a substantial vertical timber set externally on one side of the corner post (if the building is framed)

25 Roof verge. Compare the

thickness of the mortar fillet

in this example, produced by

the introduction of counter-

battening on top of the rafters,

to that shown in Figure 18. The

deep mortar bed needed here

to accommodate the depth of

the extra batten results in a less

visually satisfactory verge.

26 Oast taper tiles:

(a) two widths of oast taper tile

still commercially available

(b) alternative eaves details to

oast chambers (after Walton,

R A E, 1984).

27 Historic lime mortar-

jointed tile-hanging:

(a) general effect

(b) with mortar fillet at verge.

26(a) 26(b)

27(a) 27(b)

Detail

0 5cm

25

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20 21

28(a)

29(a)

29(c)

28(b)

28 Scale comparison

between (a) wider and (b)

narrower gauge tile-hanging.

Tile-and-a-half abutments, in

both cases, indicate modern

work.

29 Tiles at corners:

(a) butt-jointed

(b) special tile

(c) modern clay tile-hanging.

Note that, as here, the faces of

the angle tiles usually fail to line

up exactly with those of the first

plain tiles.

29(b)

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30(a) 30(b) 30(c) 30(d)

30 Different timber corner

batten details for tile-

hanging including: (a) a basic,

rustic, variety where tile tails

project a little past the edge of

the batten in places; (c) a triple-

beaded type, possibly of early

19th-century date; (e) failure of

a modern designer to detail a

corner batten properly. Almost all

the side of each tile is exposed,

negating the ‘mastering’ purpose

of the batten.

31 Corner battens in tile-

hanging are often used to

support rainwater downpipes

as they offer a good

anchorage point. It is also

possible to fix downpipes

against tile-hanging, using

patent fixings.

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30(e)

Cross-section

through corner

batten and downpipe

31

Corner

batten

Downpipe

Tiling

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22 23

32 Detailing at dormer and

sash windows:

(a) in Kent, plain wide boards

were used at the tile-hung

flanks of dormer windows, to

master the corner and provide

a rebate against which the tiling

could finish. The alternative

detail uses an architrave fixed

to the face of the board and

projecting beyond it to master

the tile ends

(b) box sash window separated

from the hanging tiles by

moulded architraves nailed to

the box faces.

33 Detail of decorated

mortar fillet on a house in

west Kent. This is modern

work, but scratching or

pressing simple designs into

exterior render has a long

history in British folk culture.

This particular detail

involves cutting a notch

from the outer bottom

corner of the board to

prevent water being

trapped behind it

32(b)32(a)

Sash box

Architrave

Cut-away three-dimensional sketchAlternative detail at dormer. The sash

box or casement frame is exposed at

the dormer corner with an architrave,

face-fixed to it to master the tile ends

Tiling to

dormer

cheeks

Sash box

Architrave

Architrave

Tiling

Window cill

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33

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34 Detailing at casement

cill showing projection and

mortar fillet.

35 Sections through walls

showing varieties of tilting

fillet:

(a) wide-gauge mortar-bedded

tiling on laths with brick wall

base forming tilting fillet

(b) similar tiling with added

timber tilting fillet

(c) the same detail with close-

gauge tiling on battens and

with a pronounced ‘bellcast’ at

the foot

(d) wide-gauge mortar-bedded

tiling on laths with timber-

framed jetty fascia acting as

tilting fillet

(e) similar condition with

cornice tilting fillet added to

jetty fascia.

Casement

frame

Cill

Mortar bed

and external

fillet to cut tile

Cut tile

Wall frame

Lead

flashing

on board

35(d)

36

Frame

‘masters’ tile

projection

Edges of tiles

project beyond

frame and are

pointed up in

lime mortar

Section through cill with

tiles fitted to underside of

cill, the top half-tile held in

place by lime mortar alone

Sections through casement windows

where tiles project beyond, and are

flush to, the window frames

35(e)35(a) 35(b) 35(c)

37

36 Varieties of decorative tile

found on buildings in south-

east England today. Most are

still being made.

37 Very occasionally tile-

hanging was painted, as in

this example. Two cases

in Canterbury occur on

17th-century timber-framed

buildings, both showing the

use of similar alternating

semi-circular and V-shaped

tiles.

34

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9 References

1 Salzman, 1952, pp230-231.2 Neve, 1969, p265.3 Clifton-Taylor in Newman, 1976, p27.4 Gwilt, 1982, p559.5 Salzman, op cit, p230.6 Neve, op cit, p217. Today the term

‘gauge’ refers to the length of the part of each tile exposed on the roof surface (Figure 10). Kent peg tile gauge today is between 90 and 100mm so either Neve was wrong or the term meant something different to him.

7 Dobson, 1971, p42.8 Bennett and Pinion, 2000, p78.9 Innocent, 1999, p180. Edlin, 1949, p117

notes that the wood of the elder trunk is ‘so hard … that it makes a fair substitute for boxwood’.

10 Minter, 1998, p75.11 Torching and bedding of tiles are

sometimes confused. Holt in Warren, 1990, p88 states that in the Middle Ages roof tiles were bedded in mud, moss or straw (straw bedding occasionally survives today in the roofs of unaltered agricultural buildings), and that tile pegs were in use ‘by the 14th century’.

12 Neve, op cit, p181.13 Bennett and Pinion, op cit, p89.14 Lloyd, 1929, p5.15 Neve, op cit, pp266-267.16 Jaggard and Drury, 1949, p208.17 Lloyd, op cit, pp20-24.18 Neve, op cit, p281.19 Clifton-Taylor, 1987, p280.20 Bennett and Pinion, op cit, p118.21 Ibid, p118.22 Clifton-Taylor, 1987, p279.23 Neve, op cit, p268.

10 Other advice

10.1 Contacts

Where work to peg tiling is being considered, the SPAB may be able to suggest the names of suitable contractors and professionals, or advise on appropriate courses that teach practical skills.For information about the Kent Local Authorities Conservation Officers Group (KCOG) contact the secretary at tony.phillips@dartford.gov.uk. The group

comprises all the conservation officers in Kent and Medway.

10.2 Bat protection

Natural England1 East ParadeSheffield S1 2ETTel: 0845 600 3078www.naturalengland.org.uk

Countryside Council for WalesMaes-y-FynnonPenrhosgarneddBangorGwynedd LL57 2DWTel: 0845 1306 229www.ccw.gov.uk

Scottish Natural HeritageGreat Glen HouseLeachkin RoadInverness IV3 8NWTel: 01463 725000www.snh.org.uk

Northern Ireland Environment AgencyBiodiversity Unit 2nd Floor, Klondyke BuildingCromac Avenue, Gasworks Business ParkBelfast BT7 2JATel: 02890 569605www.ni-environment.gov.uk

10.3 Further reading

Bennett, F and Pinion, A (2000) Roof Slating and Tiling, Shaftesbury: Donhead Publishing Ltd. Reprint of 1948 publication

Boutwood, J (1991) The Repair of Timber Frames and Roofs, SPAB Technical Pamphlet 12, 1991, London: SPAB

Clifton-Taylor, A (1987) The Pattern of English Building, 4th edn, London: Faber & Faber Ltd

Dobson, E (1971) ‘A Rudimentary Treatise on the Manufacture of Bricks and Tiles’, Journal of Ceramic History, No 5. Reprint of 1850 publication

Dunning, G C (1961) ‘Medieval Chimney-pots’ in Jope, E M (1961) Studies in Building History, London: Odhams Press Ltd

Edlin, H L (1949) Woodland Crafts in Britain: An Account of the Traditional Uses of Trees and Timbers in the British Countryside, London: B T Batsford Ltd

mastering the right-angle junction between tile-hanging to abutting elevations but in detail may take other forms, some of which are shown in Figure 30. Cover battens also provide useful fixing points for rainwater goods (Figure 31).

Timber cover strips are also used around openings for box sash windows in tile-hung walls (Figure 32). They are fitted at both jambs and head, providing an abutment to mask the edge of the tiling and to master its junction with the sash window box. They are often enriched with architrave mouldings, which increase their significance in the overall appearance of the buildings.

Lead played little part in the range of details employed in historic tile-hanging. Beneath window cills, against window surrounds and at eaves below the rafter ends, tiles were roughly cut (and fixed to the tiles beneath with mortar ‘dabs’) and the tile-to-timber joint might be finished with a lime mortar fillet (Figures 33 and 34). A frill of scalloped lead below a window cill in a tile-hung wall shows ignorance of (or disregard for) historic building practice. Where tiling projected beyond the face of a window frame, the gaps between the tile edges were pointed-up with lime mortar.

A tilting fillet supports the lowest course of tile-hanging (Figure 35). If in timber, this may be plain or take a decorative form, particularly where tiles have been used to clad over earlier, jettied, timber framing.

Most ornamental tile-hanging that survives in the region – ie tile-hanging in which the tiles have shaped bottom edges that produce a patterned effect across the wall – is of 19th-century origin. It is likely, however, that its history in the area goes back considerably further; Clifton-Taylor states that ornamental tiling was introduced at the end of the 17th century.22 Neve mentions only the ‘Scallop or Astragal … These are in all Respects like plain Tiles, only their lower Ends are in the form of an Astragal, viz. A Semicircle with a Square on each side. They are in some places us’d for Weather-tyling, and look very handsome’.23 The main variations used in recent times are shown in Figure 36. In the 19th century, these patterned forms were also sometimes used on the roof, usually in defined strips within plain-tiling, to produce similar decorative effects. Sometimes the tiles might be given a coat of limewash or paint (Figure 37). Surviving medieval illustrations might be taken to suggest that the scalloped roof tile was once much more extensively used.

7.3 Mathematical tiling

In later south-eastern counties building practice, mathematical tiles – precisely-shaped, interlocking ‘weather tiles’ – were laid to form a vertical wall face in imitation of brickwork. They were usually, but not invariably, applied to structural framing, both to hide timber frames once it became unfashionable to leave these exposed, and to provide a lightweight covering for new softwood timber frames of the period. This particular type of clay tile is a subject in its own right, and will be dealt with in a separate publication.

8 Maintenance

Lack of maintenance is a key reason why old buildings deteriorate. The essence of maintenance is preventing rainwater from getting in where it can cause harm. Water is most likely to enter through the roof, so putting right minor problems here before they worsen can prevent the need for more extensive repair.

Check your roof twice yearly. Reinstate slipped or missing tiles and replace broken ones. With peg tiles, a small degree of ‘cornering’, ie tiles with the corners slightly chipped off, sometimes does no harm, given their intrinsically varied appearance. Isolated lost tiles can be replaced by hooking the pegs over the battens or laths. This involves lifting adjacent tiles sufficiently to allow the head of the replacement tile, complete with peg, to be pushed up into position. The adjacent tiles are then allowed to fall back into place again. Any broken tiles can be stored for trimming and re-use as half-tiles at verges in the future.

Junctions in roofs are potential trouble spots. Ridge and hip tiles may work loose, needing re-bedding in soft lime mortar, and mortar fillets etc should be inspected for early signs of deterioration. In the loft, look for water staining and other signs of leaks, remembering that this may be some distance from the point of entry. Ensure that loft insulation does not block eaves ventilation, promoting dampness and timber decay.

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Gwilt, J (1982) The Encyclopaedia of Architecture, New York: Crown Publishers. Reprint of 1867 publication

Innocent, C F (1999) The Development of English Building Construction, Shaftesbury: Donhead Publishing Ltd. Reprint of 1916 publication

Jaggard, W R and Drury, F E (1949) Architectural Building Construction: Volume 2, 2nd edn, Cambridge: Cambridge University Press

Jaggard, W R and Drury, F E (1950) Architectural Building Construction: Volume 1, 4th edn, Cambridge: Cambridge University Press

Jaggard, W R and Drury, F E (1951) Architectural Building Construction: Volume 3, 2nd edn, Cambridge: Cambridge University Press

Lloyd, N (1929) Building Craftsmanship: In Brick and Tile and in Stone Slates, London: Cambridge University Press

MacManus & Partners and Cullen, G (1967) Tenterden Explored: An Architectural and Townscape Analysis, Maidstone: Kent County Council

Minter, P (1998) ‘Clay Roof Tiles’, The Building Conservation Directory, Tisbury: Cathedral Communications Ltd, pp73-75

National Clayware Federation (c1950s/60s) ‘Co-ordinated Standard List, 4A, 457’, Bridgwater: National Clayware Federation

Neve, R (1969) The City and Country Purchaser and Builder’s Directory, 2nd edn, Newton Abbott: David & Charles Ltd. Reprint of 1726 publication

Newman, J (1976) West Kent and the Weald, Pevsner Buildings of England Series, 2nd edn, London: Penguin Group. Introductory section on materials by A Clifton-Taylor

Newman, J (1983) North East and East Kent, Pevsner Buildings of England Series, 3rd edn, London: Penguin Group. Introductory section on materials by A Clifton-Taylor

Salzman, L F (1952) Building in England down to 1540: A Documentary History, London: Oxford University Press

Walton, R A E (1984) Oasts in Kent, 16th–20th Century: Their Construction and Equipment, Maidstone: Christine Swift

Warren, J (ed) (1990) Wealden Buildings: Studies in the Timber-framed Tradition of Building in Kent, Sussex and Surrey, Horsham: Coach Publishing

The Manifesto of the Society for the Protection of Ancient Buildings

11 Glossary

Abutment: In this context, the junction between a roof and structural feature that rises above it, such as an adjoining wall or chimney stack.Barge board: A wide sloping board set edge uppermost along the top of a gable. It may be carved or ornamented.Batten: In this context, a narrow length of sawn timber, rectangular in cross-section, on which tiles or slates are fixed (cf. lath). Also a timber used to cover or master a junction, as at a corner where two tile-hung walls meet.Cold roof: Where the rooms immediately below a roof space are fully insulated and sealed at ceiling level against the loss of heat and water vapour. The roof void, therefore, becomes cold.Common rafter: One of a series of ordinary timber rafters of equal cross-sectional size that do not form part of a roof truss although they may be carried by one where their loads are transferred onto heavier, principal rafters by purlins. They support the groundwork onto which tiles or slates are fixed.Counter-batten: A batten laid at right angles to, and over or under, other battens; or the process of laying battens at right angles to other battens.Course: In this context, a single row of tiles or slates across a roof or wall.Dormer window: An upright window, usually with its own roof, that is built into a pitched roof and lights a room within it.Double-lap: The overlap formed by the tail of a tile or slate lying over two courses below.Eaves: The lowest and/or overhanging edge of a roof (cf. verge). Where the lowest edge, it is detailed to shed rainwater, frequently into a gutter.Fascia: In this context, a wide board set edge uppermost and running horizontally along the margin of a roof, especially at the eaves (cf. barge board). It may carry a gutter.Fillet: In this context, a narrow strip, of

wood or mortar.Fixing: In this context, a nail, peg or cleat.Flashing: In this context, a metal strip, commonly of lead, fixed over a joint or surface to form a weathering. Flashings are used as an alternative to mortar fillets at abutments, where they are tucked into the masonry joints and may overlap the upstand of soakers.Gable: The upper part of an external wall, often triangular, at the end of a pitched roof (cf. hip).Gambrel roof: A hipped roof with a small gable at the ridge or the vernacular equivalent of a mansard roof.Gauge: In this context, the spacing between the top edge of one lath or batten and the next on a roof slope or wall. It is equal to the exposed length of a tile or slate.Head or end lap: With double-lap tiling or slating, the length by which a course overlaps the next but one below.Hip: The external angle formed where the sides of two adjacent roof slopes meet (cf. valley). It occurs where the end of a pitched roof is sloping, rather than, as with a gable, standing vertically.Hip rafter: The rafter forming the angle between adjacent slopes of a hipped roof.Lath: In this context, a strip of riven (split or cleft) timber, rectangular in cross-section, on which tiles or slates are fixed (cf. batten).Mansard or curb roof: A roof with two different pitches on each side, the lower one longer and steeper than the upper. It may be referred to as a gambrel roof on a vernacular building.Mortar fillet: A narrow strip of mortar. May be used with or without soakers as an alternative weathering to flashings at abutments. Also employed along verges.Pitched roof: A roof that slopes at more than 20º to the horizontal.Principal rafter: One of the larger rafters that, if present, forms the upper part of a timber roof truss. It carries the purlins, which, in turn, support common rafters.Purlin: A member running along the length of a roof frame to provide support for common rafters at their mid-spans or for profiled sheeting. Carried by trusses or cross-walls.Rafter: One of the inclined members that forms the top of the frame that supports a roof and determines its pitch.Ridge: The apex of a pitched roof, as where the tops of two opposing slopes meet (cf. valley).Roof pitch: The angle of elevation of the roof structure from the horizontal. It is determined by the slope of the rafters. The

actual pitch of a tile or slate when laid will be less than the roof pitch.Soaker: A small, concealed piece of metal, commonly lead, sandwiched between double-lap tiles or slates to form a weathering at hips, valleys and abutments. It is turned up at an abutment and covered by a flashing or mortar fillet.Sprocket or cocking piece: A short timber nailed to the top or side of a rafter foot to reduce the pitch of a roof and thereby extend the eaves out and away from the wall.Tile drop or nail: See under ‘Tile peg or pin’.Tile peg or pin: A timber or metal fixing that is passed through a tile or slate to hang it from a lath or batten. Those made of metal are sometimes referred to as drops or nails.Tilting fillet: A piece of timber nailed along the eaves of a roof to raise a little the lowest course of tiles or slates, thereby keeping them at the same angle of tilt as the rest. It may also be used to support the lowest course on a tile-hung wall.Torching or tiering: Lime mortar applied to the underside of tiles or slates to check the entry of wind, blown snow and dust through gaps. It also helps to hold tile pegs in place.Truss: A triangular framework designed to support a roof, bridge etc.Underlay, sarking or roofing felt: In this context, a thin, flexible sheet that may be laid beneath battens or laths on a roof to check the entry of wind, blown snow and dust through gaps. It also allows work to proceed during wet weather.Undercloak: An underlayer of tiles, slates or boarding at the eaves or verge of a roof. It provides a foundation upon which the tiles or slates above can be laid neatly.Valley: The internal angle formed where the sides or bottoms of two adjacent or opposing roof slopes meet (cf. hip or ridge).Verge: The side edge of a roof (cf. eaves), which slopes with the pitch. Often detailed to direct rainwater back inwards onto the main field of the roof.Wall plate: In this context, a timber laid on or in a wall to distribute the load from rafters, joists or roof trusses.

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