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Cladding Systems
NHB00001317 _0001 NHB00001317/1
Cladding Systems
Table of Contents 1. Cladding Definition ................................................................................................................ 4
2. Types of Cladding .................................................................................................................. 5
2.1 Rainscreen Cladding ............................................................................................................ 5
2.2 Insulated Render ................................................................................................................. 5
2.3 Brick Slip ............................................................................................................................. 6
2.4 Focus of NHBC Standards Chapter 6.9 ................................................................................... 6
2.5 The Cladding Package .......................................................................................................... 6
3. Rainscreen Cladding system properties .................................................................................. 2
3.1 Durability ............................................................................................................................ 3
3.2 Junctions, Interfaces & Openings Details ............................................................................... 3
3.3 Fixi ngs ................................................................................................................................ 4
3.4 Rainscreen CladdingTesting ................................................................................................ 5
3.4.1 Fixings .......................................................................................................................... 5
3.4.2 Water ........................................................................................................................... 5
3.5 Rainscreen Cladding area for consideration ........................................................................... 7
4. Insulated Render system properties ....................................................................................... 8
4.1 Durability of Render ............................................................................................................. 9
4.3 Fixings .............................................................................................................................. 10
4.4 Certification ...................................................................................................................... 10
4.4 Other Areas for Consideration: Insulated Render ................................................................. 10
Weather resistance ............................................................................................................. 10
Insulation ........................................................................................................................... 11
Thermal bridging and condensation ..................................................................................... 11
Reinforcement .................................................................................................................... 12
Tolerances .......................................................................................................................... 12
5. Brick Slip Cladding system properties ................................................................................... 13
5.1 Fixi ngs .............................................................................................................................. 14
5.2 Other Areas for Consideration: Brick Slip .................................... Error! Bookmark not defined.
6 General Considerations for all Cladding systems ................................................................... 16
6.1 Loading & Fixings ............................................................................................................... 16
6.2 Fire stopping and compartmentation .................................................................................. 16
6.3 Interfaces .......................................................................................................................... 19
6.4 Movement allowances & Design Tolerances ........................................................................ 20
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6.5 Condensation .................................................................................................................... 21
6.6 Cladding Damage ............................................................................................................... 21
6. 7 Building Regulations .......................................................................................................... 22
6.8 Certification ...................................................................................................................... 22
7. Summary of NHC requirements within Technical Services .......................................................... 23
Appendix 1. Rainscreen cladding guidance Note: .......................................................................... 24
Appendix 2. Insulated Render cladding guida nee Note .................................................................. 26
Appendix 3. Brick Slip Cladding guidance Note ............................................................................. 27
Appendix 4. Rainscreen Cladding Testing ..................................................................................... 29
Appendix 5. Sectional drawing examples ...................................................................................... 31
NHB00001317 _0003 NHB00001317/3
Cladding Systems
The purpose of the workbook is as a reference for particular technical elements for warranty risk
management, in this case the workbook will cover Cladding systems.
Each workbook for each technical element will follow the same format and will outline the following:
• Principles of system including the purpose, overview and make up
o Systems available, including those which are deemed acceptable by the NHBC
• Relevant NHBC standards
• Links to the Building Regulations (where applicable)
• Fire (where applicable)
• Testing methods, certification and what is acceptable (onsite and offsite)
• Key areas of risk
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Cladding Systems
1. Cladding Definition Cladding can be described as the light weight impervious barrier that forms the outer leaf of a
building, which can be applied to a multitude of backing walls and covers more than one storey in
height.
Under NHBC chapter 6.9 /Curtain Walling and Cladding is defined as:
'Coupled door and window frame assemblies (including spandrel panels) one storey or more in height
or are not contained between a structural floor and ceiling '.
When designed and constructed correctly the potential benefits of cladding systems are numerous.
However, these benefits can quickly be lost ifthe cladding is not designed and installed correctly.
Most systems allow for the penetration of rain, snow or hail into the cavity, therefore careful
detailing is required in order to prevent water crossing the gap and penetrating the structure
beyond.
With this in mind it is essentia I that systems specified by the designer a re appropriate for their
intended uses and that relevant testing is carried out by a UCAS accredited body. The results of such
tests should be made available to NHBC.
This workbook splits cladding systems into Rainscreen, Insulated Render and Brickslip to aid in
review. A separate workbook has been produced for Curtain walling.
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Cladding Systems
2. Types of Cladding
2.1 RainscreenCladding Rainscreen Cladding is defined in NHBC Standards Chapter 6.9 as:
"A multi-layer fac;:ade fixed to the outside ofthe building structure that provides a barrier to wind
and rain. The system normally includes a vapour control layer, air barrier, supporting framework and
fixings, insulation, breather membrane, cavity /air gap and cladding panels."
2.2 Insulated Render Insulated Render is a proprietary render system applied externally to an insulation material. The
insulation may be fixed directly to the backing wall if masonry or concrete, however in the cases of
metal or timber, a minimum 15mm drained cavity (and ventilated for timber) is required. Water
penetration is resisted by the impervious nature of the material. Any water ingress or condensation
within the cavity can be drained.
lt is a thermally insulated, protective, decorative exterior cladding procedure involving the use of
expanded polystyrene, mineral wool, polyurethane foam or phenolic foam, finished with a top coat
of reinforced cement based, mineral or synthetic finish render.
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2.3 Brick Slip Brick Slip Cladding is a system fixed to a backing wall usually by a supporting carrier. The backing wall
may be concrete or masonry for which no cavity is required. In the cases of metal or timber framing,
a minimum 15mm drained cavity (and ventilated for timber) is required. Water penetration is
resisted be the impervious nature ofthe material.
Any water ingress or condensation within the cavity
can be drained.
For the purposes of this document, Brick Slip
Cladding refers to a solid tile, specifically
manufactured to simulate the face of a brick usually
about 25mm thick. This brick is then mounted on a
suitable carrying system which in turn is then fixed
to the backing wall. The system is used to simulate
brickwork construction.
2.4 Focus ofNHBC Standards Chapter 6.9 The paragraph headings in Chapter 6.9 identify key areas of builders and designers should focus on
with regards to all cladding systems are as follows:
• Certification • Installation and tolerances
• Loads, movement and fixings • Electrical continuity and earth binding
• Support & fixings • Maintenance
• Durability • Glazing, gaskets and sealants
• Interfaces • Cavity barriers and firestops
• Insulation • Ventilation screens
• Damp proofing and vapour control • Handling and Storage
2.5 The Cladding Package The NHBC Standards Chapter 6.9 'Curtain walling and cladding' sets out the minimum benchmark for
satisfactory assessment and certification in respect of design, materials and sitework. The
submission will need proof of design, performance testing and certification covering the actual
building design type and method of proposed installation of the system which includes:
• A preliminary performance based specification for each product, material or fac;:ade system
being used
• Architectural/construction horizontal and vertical section details, confirming build up,
weather protection, fire stopping and interfaces
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• Elevations indicating the location and layouts of each cladding type
Prior to start of construction on site the following should be provided:
• Manufacturers Product certification i.e. Third party assessment and certification (off site
testing) from BBA, BRE, CWCT (Centre for Window and Cladding Technology at Bath
University).
• Other certification bodies or test documentation may be accepted if they are considered by
NHBC to be a suitable alternative, guidance is given with regards to this within in SOP
• Details ofthe durability for porous panels including frost ratings suitable for the location
weather severity.
• Design and details of Interfaces that will exist between cladding I curtain walling I other
elements of the building
• Design of Movement (deflectionlthermal/etc) in accordance with manufacturers' guidelines
compared with the actual building
• Methods of Fixing- details in accordance with relevant design requirements for the building
and fac;:ade I element type including offsite pull out tests of connections.
This information should demonstrate that the design of the system is within the scope of the
certification and test documentation.
Where buildings are over 18m all materials within the external envelope need to be of limited
combustibility, guidance note??? Should be referred to.
On site water testing in accordance with CWCT requirements is required to this element of the
fac;:ade.
Builders should be using a whole-system approach for cladding packages due to the variety of
factors that have to be considered within the design, i.e. wind loads, weight and dimensions of
cladding material, fixing etc.
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Cladding Systems
3. Rainscreen Cladding system properties
Rainscreen cladding is an external jointed skin that prevents the majority of rain water from
penetrating a wall. The inner airtight structure acts as a final barrier against water with any water
that does penetrate the outer skin of cladding, through joints due to forces of wind, surface tension
and capillary action, being drained away. Between these two skins is a ventilated cavity where
water is drained or allowed to evaporate.
Pressure equalization is a methodology for minimising the amount of rain water penetration by
controlling the various forces that act to drive rain water into joints in the cladding. lt is a
development of the drained and ventilated cavity where as far as possible the forces on the outside
and inside ofthe rainscreen are balanced. Controlling the forces should eliminate the passage of air
pressure induced water penetration.
The pressure equalization clause within the NHBC Standards is necessary because wind pressures
across a fac;:ade vary significantly and are constantly changing. To avoid some areas being created in
the fac;:ade where pressures encourage the influx of water and as a way to manage drainage,
compartmentation and pressure equalization of the cavity is necessary. Pressure equalization is
achieved by calculating and coordinating the number and location of vents with the volume ofthe
cavity. Dividing the fac;:ade cavity into smaller sections (i.e. 6.0m x floor height) enables pressure
equalization in these sections to take place individually across non-uniform fac;:ade wind pressures,
therefore limiting the ingress of rainwater to the whole fac;:ade.
+1+----jf-- msulabon neally fitted between upport frame
Rainscreen cladding support systems provide a range of benefits for both new-build and refurbishment schemes. These include:
• Good thermal performance, allowing designers to meet the highest environmental standards
• Ease of installation or buildability, reducing construction time and costs compared with traditiona I construction
• The ability to accommodate a range of finishes and materials.
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3.1 Durability Performance ofthe cladding system is critical and failure can have major consequences. All cladding
systems scheme are different and therefore must be assessed individually. The rainscreen cladding
system should be fabricated and installed with corrosion resistant or adequately protected materials
and with the supporting structure having the same durability as the panels it supports ..
Fixings and bracketry should normally be stainless steel or suitable non-ferrous metal.
The risk of bimetallic corrosion should be avoided by the isolation of dissimilar metals.
Aluminium components should be separated from direct contact with cementitious surfaces.
The rainscreen cladding system should not include materials liable to infestation attack by micro
organisms, fungi, insects or vermin.
3.2 Junctions, Interfaces & Openings Details Construction details for cladding interfaces and junctions should be provided. This should include the
following information as a minimum:
• Manufacturer and construction I installation details of the fire stopping provisions between
compartment walls/ floors behind the cladding and about all openings (incl. windows) into
the cavity.
• Construction details to all projections through the external envelope. This would include
EPDM's around extract ducts/vent, doors and windows and balcony fixings.
Concrete Rainscreen cladding panel,
from Forticrete
<--35mm
225mm
Aluminium Composite
Material (ACM)
Rainscreen Cladding, from
Aster
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Omm(m )
openJOtn
Rain screen Minimum Cavity Widths
Minimum Air Gap
0 0 0 0 0 0
Cl
0 0 0 0 0 0
Cl
0 0 0 0 0 0
• SOmm for panels with open joints, or
• 38mm for panels with baffle or labyrinth (rebated) joints
/Ort m 'm t>) O{>Ht }olnl
IOmm(mlnJ D ffi«J}DI~r
3.3 Fi • Baffled, open and labyrinth joints to have m in 10mm opening
to the structure with brackets and primary fixings. A wide variety of fixings are available and again
these will be designed to be suitable for the cladding panels they will be supporting. Fixing can be
visible or invisible usually attaching the panels to a bracket support system, fixing at predetermined
points, both vertical and horizontally, to accommodate movement within the system.
The two types of fixings used are Mechanical fixings, typically hangers and stud anchors or screws,
and Structural adhesive bonding/fixing used where suitable for cladding such as aluminium, copper
and stainless steel.
Details ofthe external envelope structural fixing and calculations should be provided at warranty
design review. This should include the following to demonstrate compliance with Chapter 6.9 of
NHBC Standards:
• Manufacturer fixing details for each ofthe fac;:ade types taking into account all movement
(thermal, structural, etc)
• Installation requirements including spacing and edge distances and accessories such as
locking nuts and washers
• The isolation of dissimilar metals,
During construction:
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• Fixings not subject to proof load tests will need to be installed to the correct torque setting
and re-torqued. These fixings should be suitably marked on both occasions and QA sheets
made available to the NHBC Inspector upon request.
3.4 Rainscreen Cladding Testing
3.4.1 Fixings NHBC Standards 6.9- D8 (a) states that:
"Pull-out or distructive testing of anchors should be carried out in accordance with the design,
BSSOBO and the Construction Fixing Association Guidance Note 'Procedure for Site Testing
Construction Fixings'. Tests should be carried out at a suitable rate agreed with NHBC. The test
results should be made available to NHBC."
BS 5080-1:1993 Structural fixings in concrete and masonry - Partl: Method of test for tensile loading
describes how a structural fixing should be tested (mainly under laboratory conditions), and includes
how the base material should be described, installation ofthe fixing, test apparatus and
methodology and how the testing should be reported. Further details in Appendix 4
Confirmation of on-site proof load (pulling) tests should be undertaken to the fixings into the main
structure in accordance with BS 5080 and the Construction Fixings Association Guidance Note
'Procedure for Site Testing Construction Fixings'. Tests should be carried out at a suitable rate agreed
with NHBC, and the test results should be made available to NHBC (generally, proof load tests should
be a minimum of 2.5% of the total fixing number or at least 3 whichever is greater and to a suitable
factor of safety).
3.4.2 Water
On site water testing is required to rainscreen and cladding elements (including interfaces) ofthe
fac;:ade, with reference to NHBC Standards Chapter 6.9. This should always be carried out in
accordance with the CWCT Standards for onsite testing, and undertaken or witnessed by an
accredited testing body i.e. U KAS registered.
At least 5% ofthe completed walling system should be tested with particular focus on vulnerable
areas such as joints I interfaces between elements, as agreed with the NHBC Surveyor. This sample
test is required to demonstrate adequate manufacture and installation.
The documentation required by N HBC and checked during the Design Review stage should include:-
• A set of elevation drawings annotated to show the proposed areas for testing.
• Details of how the tests are to be carried out in accordance with CWCT requirements (or
equa 1/better).
• Any failed test reports outlining the failure/cause and be submitted prior to agreement of
any remedial works proposals (local or generic to the fac;:ade).
• A final report detailing the findings of the successful test should state a 'PASS' and not that a
leak could not be observed because the internal face had been constructed. This means that
the internal lining of the external walls should not be fixed before the test has been
carried out in those areas identified.
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NHBC Standards Chapter 6.9- S12 (f) states that:
"On site hose or sparge bar testing should be carried out with particular emphasis on interfaces that
are designed to be permanently closed and watertight. The building should remain watertight during
and after the test."
There are three different approaches to site testing described in CWCT Technical Note 41. These are:
• Hose testing
• Spray bar testing
• Cabinet testing
All tests should include pass certification and photographs. Any failures should be reports with
remedial measures and retests confirming pass. A detailed CWCT test Report will cover all these
points.
Hose Testing
As the name suggests hose testing uses one jet of water
which is sprayed onto the cladding system to test
permanently sealed joints. A spray bar test is usually more
suited to an open or baffled joint.
As guidance, testing of 5% ofthe fac;:ade of curtain walling is
stated in the NHBC Standards applicable to Curtain Walling
systems. This% might also be applied to cladding in terms of
the number of junctions with windows to be tested.
Hose testing is good for testing permanently closed
joints as it provides water pressure to force water
through weak areas. This is very quick test as the
hose is passed for around 5 minutes and any water ingress tends to be immediate.
Spray Bar Test
The spray bar test is a test for runoff and is suitable for testing open jointed systems such as
rainscreen cladding. Sparge bars can be used on pretty much all facades as they spray the
fac;:ade with a large quantity of water. This normally takes around an hour per section -
30
for 30
spraying for
minutes and
observations
minutes.
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Cabinet Testing
This is a test that creates a positive pressure difference on the cladding system whilst spraying water
onto the external face. lt is rarely seen on site due to the difficulties affixing and sealing the cabinet
unit to the cladding, but is suited to testing doors or windows after installation.
CWCTTechnical Note 41 provides further details ofthe methodology used.
3.5 Rainscreen Cladding area for consideration
In addition to those areas for concern highlighted within the Curtain Walling (Add detail from Curtain
wall book) workbook, the following areas should also be considered.
The purpose of the Rainscreen Cladding is to ensure that water is prevented from reaching any parts
ofthe wall that could be adversely affected by the presence of moisture.
The outer skin is not designed to be completely impervious and a small amount of water penetration
is expected within the cavity area between the outer and inner leafs. However any moisture that
does penetrate into the cavity should be redirected back to the external leaf via the use of open,
baffled or labyrinth (rebated) joints.
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In order to ensure that water ingress within the cavity is kept to a minimum, the minimum width for
air gaps/cavity for cladding panels with open joints should be 50mm this gap can be reduced to
38mm for panels with baffled or labyrinth (rebated) joints and clear cavity.
50mm (mrn) 38mm (minJ
1-
Of:-'M join~ birffl~d or ra~byrjnth {re-batell'J · in~
Rainscreen Minimum Cavity Widths
Minimum Air Gap
• SOmm for panels with open joints, or
• 38mm for panels with baffle or labyrinth (rebated)joints
• Baffled, open and labyrinth joints to have min 10mm opening
This air gap should be adequately ventilated with cavity trays provided above openings, at the base
ofthe rainscreen and at interfaces where necessary.
Particular attention should be given where rainscreen cladding interfaces with other elements of
construction, other cladding systems, and curtain walling. External and internal air and water seals
should be provided at all interfaces. Further guidance can be found in "NHBC Technical Standards -
Appendix 6.9-A".
A minimum opening of lOmm should be provided to panels with open, baffled and labyrinth joints
and a screen to prevent birds and animals entering the cavity should be provided to all penetrations
through the cladding (this should include the top and bottom of the cladding).
"The rainscreen cladding system should be designed to minimise the risk of thermal bridging and,
surface and interstitial condensation. A vapour control layer should be provided unless a
condensation risk analysis in accordance with BS 5250 shows that one is not necessary. The vapour
control layer should be fixed on the warm side ofthe wall insulation."
4. Insulated Render system properties Insulated Renders are commonly rigid board insulation coated with a mesh reinforced acrylic finish
to any colour. The finish is deemed as faced sealed -only watertight ifthe acrylic is not damaged in
any way.
In terms ofthe functionality of a building, Insulated Render can have a key role in helping building
designers to meet the stringent criteria outlined in the Approved Documents.
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lt allows designers to significantly improve the energy-saving performance and thermal insulation of
the building whilst providing an attractive and durable exterior finish.
Insulated Render fulfils the functions of thermal insulation and protecting the building against the
influences of weather, however it is not responsible for making the external wall airtight. lt is
therefore imperative that care is taken to ensure the Backing wall is suitably sealed prior to the
application ofthe Insulated render. Masonry walls should be jointed to a high standard with all joints
and penetrations filled. Framed walls should be provided with a rigid sheathing on the cavity face
with all joints taped and sealed. Proprietary render systems should be specified in accordance with
the manufacturer's recommendations and include the correct number and thickness of coats.
4.1 Durability of Render The system should be designed with corrosion
resistant or adequately protected materials - fixings and bracketry are normally stainless steel, non
ferrous metal or plastics and the risk of bi-metallic corrosion should be avoided (aluminium/alloys
should not come into contact with cementious material).
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The system should not include materials liable to infestation attack by microorganisms etc.
4.3 Fixings Pull out or destructive testing of anchors and fixings should be carried out in accordance with
the design, BS5080 and the Construction Fixings Association Guidance Note /Procedure for Site
Testing Construction Fixings' and available to NHBC.
For adhesive fixing, attention should be given to suitability for use with the backing wall,
preparation of the adhering surfaces and supplementary mechanical fixings as required by the
design.
4.4 Certification All render systems should have third party accreditation
4.5 Insulated Render: Other Areas for Consideration
4.5.1 Weather resistance The system should satisfactorily resist the passage of moisture to the inside of the building
For timber and steel framed backing walls, a cavity of at least 15mm should be provided
between the wall and insulation to allow any moisture to drain away. Where the backing wall is
timber frame, the cavity should be suitably ventilated in accordance with Chapter 6.2.
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Suitable precautions to resist impact should be included in the design (such as provision of a
rigid board behind the insulation whilst maintaining the cavity).
5teelframe
t5mm (mlnJ dl"ained ("<!vl'tlt
r 5mm (m In) dr-a "ned and ~~Mtilated c:av·
Render System Minimum Cavity
Widths
• Render system and backing wall
to resist passage of moisture
• 15mm cavity drained and vented
to timberframe
• Drained to steel frame
DPC/DPM trays with stop ends should be provided above openings, cavity barriers and at the base of
the system to ensure that water is drained to the outside.
BBA certification is the most likely form of certification
Most accreditation does not state a drained cavity- NHBC requirement only.
N HBC states a cavity to provide two means of preventing water ingress as any other wall.
Where a cavity is provided, drained only ones should not affect the thermal resistance ofthe
construction too much as it is a static air space but be wary of drained and vented cavities
such as for timber frames as extra provisions may need to be provided.
4.5.2 Insulation The insulation type should be suitable forthe intended purpose and ensure continuity around
openings
Should be securely fixed to the support frame/backing wall with appropriate fixings
(size/number/spacing/em bed me nt) including a minimum of one non-combustible fixing per
square meter or per insulation batt and fixed through the mesh reinforcement
4.5.3 Thermal bridging and condensation The system should be designed to minimise the risk ofthermal bridging and surface/interstitial
condensation
A condensation risk analysis should be carried out in accordance with BS5250. Unless it shows
otherwise a vapour control layer should be fixed on the warm side ofthe wall insulation.
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4.5.4 Reinforcement Reinforcement mesh should be included in accordance with the manufacturers
recommendations -typically where there are likely to be areas of increased stress (corners of
windows/door openings). Laps should not be less than lOOmm and appropriate trim used at
corners/interfaces.
4.5.5 Tolerances Reasonable tolerances are set out in Chapter 1.2 and if coloured, batching should be undertaken to
maintain consistency.
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5. Brick Slip Cladding system properties
With brick finishes still as popular today as they have been for centuries, designers often turn to
Brick Slips as a way of providing a traditional finish. Modern methods of construction often prevent
traditional brickwork from being utilised. Brick Slip systems provide the designer with a solution,
allowing modern buildings to adopt a traditional brick finish and tactfully blend into surrounding
architecture. Brick slip cladding can be applied to different backgrounds dependant on the
manufacturers system details.
For Brick Slip Cladding NHBC Standards Chapter 6.9 requires the following:
• Weather Resistance- Brick slip cladding systems, together with the backing wall to which
they are applied, should satisfactorily resist the passage of moisture.
• For timber and steel framed backing walls a cavity of at least 15mm should be provided
between the wall and the brick slip cladding system to allow any moisture to drain away.
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• Dpc/dpm trays with stop ends should be provided above openings, above cavity barriers, at
the base ofthe brick slip cladding system and at interfaces where necessary to ensure water
is drained to the outside.
• The brick slip support system should not obstruct the drainage paths.
• The brick slip cladding system should be designed to minimise the risk of thermal bridging
and surface and interstitial condensation. A condensation risk analysis in accordance with BS
5250 should be carried out to include high occupancy conditions.
• The vapour control layer should be provided -fixed on the warm side ofthe wall insulation
unless shown to be otherwise by a specific condensation risk analysis for the wall build-up.
Where hung, guidance under rainscreen cladding may be followed for brickslip systems.
5.1 Fixings
As identified above, the method affixing brick slips has caused problems in the past and this is why
the BRICK SLIP condition makes specific reference to the manufacturers' fixing details including
reference to the design wind load ofthe building.
Of interest is a Technical Information Sheet 15 produced by lbstock which examines the fixing of brick slips and the various categories of adhesive. lt states that 'fixing may be by a combination of mechanical support and adhesive mortars or, in increasing situations, by adhesives alone" and lists
different types of adhesive (for fixing to concrete substrates) and provides guidance as follows:
1. Sand/Portland cement mortar- not recommended for slip fixing due to an adequate bond strength rarely being attained.
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2. Sand/Portland cement mortar with Styrene Butiadiene Rubber (SBR)- is available in ready mix form and can achieve high bond strength if correct installation procedures are followed.
3. Epoxy and polyester resin- can achieve high bond strength and rapidly harden, but often
require support until curing has taken place. Other factors are high cost, unsuitable for larger bed depths and temperature sensitivity.
4. Cement based adhesives- can achieve a bond strength nearly as high as Epoxy and
Polyester and similar in application to traditional mortar.
5. Rubber latex based material -can take into account a degree of movement and vibration
due to their flexibility. Lower bond strength but relatively easy to work with.
6. Silicon based adhesives -often used with proprietary brick slip systems with mortar pointing to be carried out on site.
Brick Slip Cladding Systems FIXING
Fixing systems should be accurately set out to ensure brick slips suit storey heights, lintels, corners and openings. Fixing can be adhesive such as Ronacrete's product Ronafix (BBA 89/2149} or metal such as Ancon.
As with other cladding systems, the fixing of Brick Slip systems should be designed to account for site specific conditions such as wind loads and it may be that a combination of fixings is required.
Mechanical fixings should be as specified by the manufacturer/designer to cater for site specific conditions. Quantities/spacing/embedment depth should be specified and a quality check process carried implemented on site to ensure that fixings are installed as designed. In addition, a
percentage of fixings should be load tested to prove adequacy.
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6 General Considerations for all Cladding systems
6.1 Loading & Fixings
Dead and live loads should be transferred to the structure without undue permanent deformation or
deflection of any component.
The vertical profiles attach to the brackets via a combination of fixed and flexible points. This is because the support system has to support both dead and dynamic loads, as well as accommodating the expansion and contraction of materials.
Every element of the facade construction must have only one fixed point, which absorbs both vertical weight loads and horizontal wind loads. Fixed points means that rails are connected to the
bracket through the round holes in the bracket.
Flexible points are vital due to the divergent thermal performances ofthe materials being combined,
which cause them to expand and contract at different rates. They are also needed to absorb dynamic horizontal wind loads. In effect, the facade has to be able to float on the sub-construction.
The rails are therefore fixed through the elongated holes in the brackets
6.9- Cladding systems shall be securely fixed in accordance with the design Brick slip cladding systems should be securely fixed in accordance with the design and the manufacturer's recommendations. The type, size and positioning of all anchors, fixing rails, frames, fixings, fasteners and bonded joints should be in accordance with the design. Anchors, (ixinqs and bracketry should normally be stainless steel, suitable non-ferrous metal or appropriate plastics.
6.2 Fire stopping and compartmentation
6.2.1 Compartmentation The cavity of a rainscreen cladding if left completely open could be considered a chimney that
permits the transmission of fire and smoke around the whole fac;:ade of a building. lt is for this
reason that compartmentation and cavity barriers are needed.
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Fire barriers in rainscreen construction can be more difficult to deal with due to the need for a
drained and ventilated cavity but are critical to prevent fire spread through the concealed void.
Cavities should be closed around openings such as windows (by a suitable material to avoid fire
breaking into the cavity), at junctions with compartment walls and floors and also to restrict the
maximum dimension within a cavity to 20m where the surfaces ofthe cavity are Class 0 or 1 (limited
combustibility) and lOm in other cases.
In buildings of over 18m in height, insulation and filler materials in walls is required to be of limited
combustibility forthe entire envelope. Kingspan® Kooltherm® KlS rigid insulation is currently the
subject of debate and further investigation after its suitability for use in certain construction types of
buildings over 18m has been called into question.
The CWCT Standard for systemised building envelopes (2006) requires that cavity widths a re not
reduced by more than 50% ofthe minimum at fire barriers (and at support rails).
There are a few solutions to achieving this. One is to use a barrier which partially blocks the cavity
with intumescent material on the leading edge which in the event of a fire, will expand and close off
the cavity. Another solution is to use slotted metal plates coated in intumescent material which
when activated with heat, will close offthe slots, although the CWCT guidance note suggests testing
has found these products to be less effective than the former solution. Joins in the rainscreen close
to a fire break can also be an issue and may require localised protection of areas.
At present there appears to be no one standard guide only the need for compartmentation of the
cladding with critical areas highlighted in the literature. Exactly how cavity barriers for fire and those
for pressure equalisation interact is also not well documented. Regardless, critical areas are:
• Around openings
• Junctions with compartment walls and floors
NHB00001317 _0024 NHB00001317/24
Cladding Systems
• Protecting fixing brackets to prevent movement of cladding away from the structure and
compromising junction with compartment walls and floors
Each project is designed on a bespoke basis with a variety of different products available and
adhering to the product manufactures details in full is critical.
----c"'T""'T~-=., -::r7"""1=r-"7d - -----,,.--"
"' ._,. 4 liR-A 11. t' !BRAN
~ .,,. " At"'
., "
" 4
" 4
"' 4 .., ..
A MORTAR (APPUED TO WHOLE SYSTEM, AFTER FlXlNG TO SUBSTRA TE) /'
4
-4
"'
15MM 11MB R BAnEN TO CRfATt 15M DRAINAGE CAVJTY
G
_ 1 7 ~-~--~~-~-~-~_n_ON_
"'
150
<111
d <1
.d ~
...
---- lNTERNALFINJ H
Gi-lT WEJGHT STEEL FRAME SY5TEfol
f SI,Jl ATION WITHIN STFEI .-----::-f-4---- FRAI·IE TO AOtiEVE REQUIRED
UlfA
BrickSiip Cladding example of Fire Stopping. The barrier is only as robust as the material it is
mounted onto and the location for installation ofthe barrier should take this into account. Fixings depth and frequency ofthe cavity barrier as well as the brick slip unit should be as specified by the design. Taken from http:/ /www.aquariancladding.co.uk
6.2.2 Insulation & Backing wall construction Where the insulation is fixed to the backing wall a minimum of one non-combustible fixing per
square metre or per insulation batt, whichever is the lesser, should be provided in addition to the
other fixings.
Reference should be made to BRE document BR135 - 2003 'Fire performance of external thermal
insulation for walls of multi-storey buildings' when specifying the type of insulation system to be
installed.
NHB00001317 _0025 NHB00001317/25
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The design should ensure that the insulation is continuous around penetrations through the
rainscreen cladding system.
Where the rainscreen panel joints are open and the performance ofthe insulation could be
diminished by moisture, a breather membrane should be provided over the outer face ofthe
insulation.
6.3 Interfaces
rnsula trbn neatly fit ed tJe-~ ~L.r~JX!ft fra 't<!'
The interfaces details between elements is of great important and details should be project specific
for the performance required at the interface. This could be a movement and/or weather proof joint at junctions such as between cladding systems or at junctions with windows. Detailing and material will depend on the system used and the situation and should follow manufacturer's guidance and/or
good practice. Junctions with party walls/floors should have suitable fire barriers. Junctions with window heads should (if necessary) allow drainage ofthe cavity.
The details in appx 5 are from Aquarian Cladding Systems are indicative of an installer's standard details for Brick Slip cladding. In this case it is for the GEBRIK system. The aspects that may require
review are indicated in the text. Gebrik, the BBA Certificate for which states -"Gebrik pointing mortar is applied in accordance with instructions and not less than one week after the panels have been installed. Pointing should not be carried out in direct sunlight."
Weather resistance at Interfaces is the most likely place where a defect can occur.
DPC's / DPM's
NHB00001317 _0026 NHB00001317/26
Cladding Systems
Provide physical barrier from water penetration
Seal arrangements which solely rely on gun applied sealant should not be used (Good
practice)
DPC/DPM's should extend the full perimeter of any opening or junction.
Interface should be designed to ensure water is diverted away from the backing wall.
Be mindful of differing materials, e.g. most silicones react badly to copper (window sealing
of copper rainscreen).
Products like EPDM's are common place for achieving a second seal to the perimeter of
curtain walling facades.
6.4 Movement allowances & Design Tolerances
6.4.1 Differential Movement A differential movement assessment should be provided prior to the warranty design review risk
assessment for the primary structure and the external cladding envelope (reference CIRIA Technical
Note 107 - Design for movement in buildings). The assessment of this information should be carried
out by their Engineers with confirmation from the designer that this assessment has been
considered and incorporated into the design.
6.4.2 Design Tolerances Line, level plumb and plane ofthe system (+/- 3mm in any storey height or structural bay width
As noted previously the causes of movement include:
• dead and live loads
• changes in temperature
• changes in the moisture content of components
• freezing of retained moisture
• creep
The genera I suitability of a system for use should be assessed as part of any 3 rd party certification.
Often certification refers the user to seek manufacturers guidance for certain circumstances in which the system is to be used. lt may be that if the system is to be used in areas prone to severe weather
conditions, a certain combination of components is recommended etc.
Dead and live loads should be accounted for within the design -numbers/types offixings should be
specified to support the cladding and the relevant design wind load applied. Fixing rails, frames, fixings and fasteners should be designed to accommodate specified loads and take account of the manufacturer's recommendations. Bonded {ixinqs of rails, frames, {ixinqs and fasteners should be specified only where there is no suitable alternative and should be designed in accordance with the manufacturer's recommendations.
Changes in temperature may not only affect the brick slip panels, but may affect the sub frame or main structure. Tolerances to account for this should be incorporated into the design. This may
NHB00001317 _0027 NHB00001317/27
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include movement joints at set dimensions -vertically every 7m for P-Ciad for example. Horizontal
movement joints should cater for the main structural components and be designed by a suitably
qualified person.
Moisture content change will be most evident with timber components. Timber frame shrinkage should be allowed for, as should expansion/contraction of metal frame components and to a lesser extent shrinkage of concrete frames.
Exposed components that retain sufficient moisture to suffer from freeze thaw action should not be
evident on such systems. Third party certification and manufacturers place limitations on the
installation of components and ofthe system as a whole with this in mind. For example, P-Ciad panels should not be installed on top of a wet backing wall. In addition, pointing mortar should only
be placed during conditions when the temperature range is from +2°Cto +30°C.
Cold weather conditions are associated with water in the mortar mix or within materials which can
cause freezing and expanding. If detailing at interfaces is inadequate, water penetration may also cause deterioration of backing or abutting materials.
Creep is a phenomenon where a material deforms during performance (under expected load) over a period oftime. Creep is more often associated with concrete structures and should be allowed for
within the design of cladding. This may be in the form of movement joints, design of secondary frames, fixings or detailing at interfaces to allow for or take into account a specified amount of movement.
Note for Brick Slip: Movement joints in the backing wall should be continued through the brick slip cladding system and formed in accordance with the manufacturer's recommendations.
6.5 Condensation A condensation risk analysis should be provided in order to establish the suitability of the proposed
system. The Condensation Risk analysis should be supported with calculations in accordance with
BS5250:2002 although the following parameters should be used:
• WINTER MONTHS conditions (Jan & Feb), where the internal conditions represent a high
occupancy i.e. RH 60%-70% at 20 deg.C, together with external temperature below -2.0 deg
C. -relative humidity
• The climate/temp etc values used for other months ofthe year should be derived from
statistical data to give typical seasonal conditions
6.6 Cladding Damage All cladding that could be easily damaged in vulnerable locations (e.g. adjacent to pedestrian/vehicle
areas) should be able to resist impact damage or be easily and readily replaced should it become
damaged. Details should be provided of how this will be achieved and where the areas identified as
zones A-D are located on elevation drawings.
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6.7 Building Regulations Applicable Building Regulations & Approved Documents :-
AD Part C2 states:- The walls of a building shall adequately protect the building and people who use
the building from harmful effects caused by:-
a) Ground moisture;
b) Precipitation including wind driven spray; and
c) Interstitial and surface condensation.
AD Part L states thermal performance support systems for cladding should limit thermal bridging.
6.8 Certification Curtain walling and cladding systems shall be adequately tested, certified and designed in
accordance with appropriate standards
NHB00001317 _0029 NHB00001317/29
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7. Summary of NHC requirements within Technical Services
Where a cladding system is being installed the NHBC requires details ofthe complete system to
enable a full assessment oft he risks. Conditions will be set when the N HBC is made aware a cladding
system is being installed and the SOP should be referred to for detailed procedural guidance.
The conditions will reflect the information N HBC require to make a full assessment of the design of
the cladding system including following:
• A preliminary performance based specification for each product, material or facade system
being used. Design, specification and installation.
• A full set of drawings -Architectural I cladding contractors construction issue horizontal &
vertical section details, confirming build up, weather protection, interfaces and any drained
cavities and fire stopping.
• Elevations indicating the location and layouts of each curtain walling and cladding type.
• Details ofthe durability for porous panels including frost ratings suitable for the location
weather severity.
• Structural engineer's design details/calculations justifying any specific designs such as
movement joints, fixing details, the isolation of dissimilar metals and consideration of
imposed loads (wind, cladding self-weight etc).
The conditions will also reflect the information NHBC require to make a full assessment ofthe
materials used within the cladding system with all materials being certified for intended use. Third
party assessment and certification (off site testing) from BBA, BRE, CWCT. Other certification bodies
or test documentation may be accepted ifthey are considered by N HBC to be a suitable alternative.
This should include manufactures recommendations for proprietary items
Verification that the installed cladding system is watertight, in the form of on-site testing. Tests
reports should identify any faults within the membrane, detail any remedial actions undertaken and
be accompanied by successful re-tests ofthe areas that failed.
NHB00001317 _0030 NHB00001317/30
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Appendix 1. Rainscreen cladding guidance Note:
e · fom a on ired o demo " e a e R:f scree e surtab e or i in ended purpose This nforma ·on should me de
1. A e ea test opportun·ty p ease prov e deta s o lhe basis for your proposed destgn to tncl de a pre tmlnary performance based spec cabon or each product, matenal or fa~e sys e ing used
2. Pro de rchi ectura and construe · n hon::o t vertical sec o de a s con rming proposed n ettlods or al tion orienta ·on of the units.
3. ar1< dupe tions nd eating the k>ca n and yo so the Rainscreen
Be ore cons 1c ·on on site lea e provide
1
2.
3.
each R nscreen and al o This ukf 1ncl e EPO s fi.xt gs.
and certification fro ·
ia on. e.
he des·gn of no eme jo· ts in acoord3nce · h al "ding.
4. En ure tha a 3Bmm m· - um c vrty t .. provided fo baffled or ed Rai creen and n i ·m of 50m 1 o open JOin ed Rmnscreen
5. e ollo ng o demons e
e a~ade types mcludJng
NHB00001317 _0031 NHB00001317/31
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- Proof load tests shoUld be 1.mderfuken to BS 5080 arnd the Canstructiorn Fixmgs Association Guidance Note 'Procedure for S!ite Testing Construction Fix- gs'_ Te-sts shoLIIId be cOilrnied mrt at a suitable rate ll'.IQ reed with NHBC, and the test resu.tt.s shouk:l be made available fo NHBC •(gernera y, proof load re&s should be a m]rfmum of 2.5% of the torn I fixing number or i!ilt least 3)_
EL Movementi. and wind-lo.ad"ng asse-ssment and Movement arnd To rances report including de-taiJs of ooy press;ur'isation requirements to open jointed Rainsareen facades.
7.. Details of the durn'liil'ity tor poroL.IIs panels induding frost ratings ~uitable for the location weo?~lller severity.
a.. Pro'!liide a set of on site water te-sts and re~Uits by UKAS accredited te-ster that - diu de a se-t of te~ to the first. completed oors. of Rain:s-ereen to ensure 51ile installation is corre-ct ood there a:re no system1c issues_ CWCT requires a n1inimum of 5% of the fa~de be tested and should include mtermces with olller elements ot the b -k:ling_
9•. A I dladding that cmild be easily damaged - vulrne-mble locations (e.g_ adj i!ilcent to pedesmanfvehicle <?~re as) should be able to resist [m~ct d!IDlage or be easily arnd read~ repli?lced ~hould it become dam aged.. Provide details of how this wi I be achieved.
Note-s
• N H BC .Sbmdards Chapter 6_9 'Curm]n walling and cladding'; sets out the minimum benchmark for satisfa.C'f.ot)t as.se$sment and rerti'liication in respect of design, mate-.rials and worikmanstlip_ lnforrna ·orn should "ndlude proof of design, perfurmanre te.sting and oortifica ion covering Hle acrum buik:ling design type :Find melllod of proposed insfa :F~tion of the system_
References
NHBC Technical Extra February 2!!112 issue !J6 NHBC Standards CH 6.9 for further guidance
NB This g,utdanoe note does no1t oo•ve r a ll .Mopects of the <desigJn, nurti:e ria~s and worrkmans lilip a 111d you are rem~ 111ded to ensure tilila1t th.ese .aspects of lllile wortcs are designed and buHI: tG comp~ with the appHcable tiiHBC Standards in ;;rtocmdance w iitlil t lile Rules app ltying to Buillderrs a111d [)evelopers .. Should you have .any queriies regtarding1 tlile above, please· •co111tac1t the NIH Ell C Project Ma111age:rr.
All infum1ffiion mould be provided at llle eartiest o~orti.un:itiy and e:ertairilly before Hlaft sectioo of the work commences on Siite, thus avoi ng any abortive v.•oriL
This guidance is applica~e at llle lime of diS<tribution arnd you ;are reminded that NHBC Standards can be subject to updates_
i'IHBC House. Davy Avenue. Knowl il . tw ilton Keynes. Bucks MK5 BP
NHB00001317 _0032 NHB00001317/32
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Appendix 2. Insulated Render cladding guidance Note
Information Guidance Note 7
Insulated Renders
This guidance note outlines the infoonation required to demonstrate that the Insulated Render System is suitable for its intended purpose. This information slloold indude the follo\Mng:-
1_ ~ro'ilide details of 1he manufacturer of the lnSUI ated Render.
2_ Manufacturers Product certification i.e_ Third party assessment and certification from: BBA, BM TRADA or CWCT (Centre for Window and Cladding Technology at Bath University)_ Other certification bodies or test dociJmentalion may be accepted if they are considered by NH BC to be a suitable alternative. The design and construction should foiiO\fil the detail of the ttlird party certification without change, a lteration or deviation_ The accreditation should cover the whole system from the proprietary system fixings to the backi~ '11'11311 through to fie render finish_
3_ ~ro'ilide corlStruction details to all projeotions oodior openings through the external envelope. This wou d in dude EPDM's around extract dud:slvent, doors and windows and balcony fi:xings_
4_ Pro'ilide conS!truotion details to demorlStrate a drained cavity of minimum 15mm is included unless the backing '11'11311 consists of solid masonry .. Please note where the structure oonsists of t imber fr.aming then the cavity would also require ventilatioo .
5_ Pro'ilide details of the fire stopping to the cavity and alw fie fire resistance of the insulation at comp.arbnent wall and floor junotions. Note: where the iMulatioo product is used above 18 metres from the external groond eve I, oonfillllalion of !i mited combustibility wi I be required for the wnole fa~ade and not just the area over 18 metres_
6_ Pro'ilide details of the external envelo,pe struotural ftxing and calculations. This will need to include the following to demonstrate compliance with Chapter 6.9 of NHBC Standards: - Manufaoturer fixing details including referenoe to the anticipated wind loads for the building_ - Details of the nen-canbuS!tible fixings as required to every 1 metre square or per insulation batt Whichever is 1he most - Proof load teS!ts should be undertaken to BS 5080 and the Construction Fixings Association Guidance Note 'Procedure for Site Testing Construction Fixings'_ Tests shou'ld be carried ol!lt at a suitab e rate agreed with NHBC, and fie test results shoU:Id be made available to NHBC (generally, proof load tests should be a minimum of 2.5% of the total fixing number or at least 3)_
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Appendix 3. Brick Slip Cladding guidance Note
Slips
Th- gu dance no e ou nes the · forma ·on required to demonstr te t a e I ula Bri S ip Sys en · su · ab or · s in e ded p rpose. is informa n shou include the o lo ·ng-
2.
3.
de ·a on. The accredi atio system fix1ngs o e ac i
e dura · ity o the Bric esi· es ere 'J e B c
and ea O'l from:
a fro m ng and fhe red o e sula ·on or
4. Pro "de constructlo deta s lO an pro·ections or ope ·ngs thro h e e emal uld · elude EPD • .. aro nd e rac ductslven doors and "ndows
5.
6. Provide details of
metres.
1.
e an c pa ed ind lo ds or e
metre squ re or per
NHB00001317 _0034 NHB00001317/34
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should be c~mied out at a suitable rate agreed with N H BC, and th:e test reSilllts should be made availallle to NI-IBC (g;erneralty, p roof load tests shoold be a mirnmu.nn of 2.5% of Hle ol:a'l fixing number or at leas-t 3) ..
Beferenges
NB TI1is g 1.1 id :1n ce note does n o'ii: oo,.ver all ,aspects o f the design materials and wmkrnanship and you are reminded to ensure hat these aspects of t he· woriks are· desiigned and laluj h't: to complly with the app l &cable NHBC St and i1rds in a:ocmdance w iit'lll the Rules ap,p ltyin.g to Buil de:rrs ilii i!HII li)evelopers. Should you have ani!{ querie.s regardingJ'lilie above, please eo ntad: the NIHBC Pm_ject M a 11.agm.
All irntam1atiorn Should be prov•aed m. Hle earliest o:~ortunitiy ~rnd certmnty before ~hat sectioo of Ule WOI"k. oommenres on Slit.e, thus avoi 1ng any abarllive work.
This guidance is appl icable at Hle time of dir.tribution arnd yau are remi ed tllat NHB C Starndards can be s-ubject to updates.
Usiirng 1he NI-IBC Extranet is the most effective and efficiem way of serndi rng d rav.ings, details 11nd infmmatiorn o Techrn·cal Staff in NHBC . To find out how to use this free faciilmy PJease go to , _ ,p~Uwww .. mh c.co . kiB~:~~ IaersJNI-I Cnewextiranetl. By uS~ing Hlis faciJity you wil l also be able to a0cess info:rmatiorn regar ng your sile(s), arnd ched . 1he status of Conditions i1pp1ica e to your siite(s).
NHB00001317 _0035 NHB00001317/35
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Appendix 4. Rainscreen Cladding Testing
The Construction Fixings Association Guidance Note /Procedure for Site Testing Construction Fixings
-2012 makes reference to BS 8539:2012 Code of practice for the selection and installation of post
installed anchors in concrete and masonry. BS 8539 includes substantial detail such as spacing of
fixings (zone of influence) about embedment depth, positioning of fixings in masonry (within a
mortar joint or a masonry unit), tensile/shear/combined loads and bending, corrosion, tightening
torque and testing etc.
BS 8539 describes two stages of a project during which testing might be required. These are:
1. To validate that the anchors are suitable for use (before mass installation)
2. Proof testing to validate the quality of installation.
Of course it is both that NHBC has an interest in, but with a focus on testing to a percentage of all
anchors (2.5% of all fixings or 3 in number whichever is greater) to validate the design and
installation. The Guidance Note states that a minimum testing of 3 fixings applies in any discrete
area where different anchors may have been used, the base material is different, the base material
may have been affected by weather conditions (different elevation) or where anchors have been
installed by different teams. A satisfactory proof test is if the required load has been held without
any movement or damage/deformation to the fixing or base material. Fixings for proof testing
should be chosen at random. The test report should record the information recommended in BS
8539 (also published in the Guidance Note) and includes the relevant information about exactly
what has been tested and when.
Unlike curtain walling, rainscreen cladding is designed to allow movement of air through a cavity so
that any moisture entering this cavity can drain and/or evaporate and should be designed as a
pressure equalised system. Rainscreen cladding should be fixed to a backing wall that is relatively air
tight and may require a separate permeable air barrier with joints taped on the cavity face of the
backing wall. Unlike curtain walling, on-site air testing is not specified in the NHBC Standards,
however the need to be satisfied that panel fixings are satisfactory for securing panels in position
still remains and hence the requirement for a rainscreen cladding to have current certification
confirming independent technical approval by an authority accepted by NHBC. For example, parts of
the CWCT mandatory test regime are Wind resistance -serviceability and Wind resistance -Safety.
A sample section of the rainscreen system will be subject to testing at a test facility for Serviceability
and Safety. CWCT Technical Note 9 examines this in further detail and in general, testing is based on
the site wind loading that is expected to occur just once in a 50 year period (minimum requirement
for CWCT is 800Pa).
Serviceability tests at positive and negative pressures for the design wind load (1 in 50 year event) so
that when this occurs, the cladding system neither fails nor ceases to be weather tight. A Safety test
determines whether the cladding has a factor of safety above the designed wind load and subjects
NHB00001317 _0036 NHB00001317/36
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the sample to pressures 50% above that ofthe design wind load. The importance here is that the
system does not fail structurally or components become detached.
Impact
A further part ofthe CWCT mandatory test procedure is Impact- Safety. This is because impacts to
the fac;:ade may occur over time and the fac;:ade should be able to resist or cope with these without
causing a hazard.
The Impact- Safety test is in place to guard against materials impacted injuring a human- either
from direct impact or from falling debris. Certain areas of a building (exposure zones) are defined in
BS 8200 and categorised A to F (A being the most prone to impact and within l.Sm of ground level).
Tests vary according to location and type of impacting body. For cladding, the preferred outcome is
negligible risk (no material dislodged, no subsequent falling material, no sharp edges & no
penetration), however low risk (maximum falling particle SOg) could be acceptable away fro m areas
where materials could fall from significant height onto people as could moderate risk (SOOg particle)
within l.Sm of the ground.
Brittle materials such as rainscreen often perform poorly but can be reinforced by bonding a mesh to
the back oft he panel to reduce the possibility of falling debris. Further detail about impact testing is
available in CWCT Technical Note 75.
Further details on Water testing
Hose testing
For a hose test, the standard distance for a hose to be placed is 0.3m from the joint to be tested and
water is sprayed perpendicular to the cladding system. Water pressure is 220 +/- 20 kPa (22 +/- 2
litres per minute) through a standard nozzle (Monarch Type B-25, #6.030 with a cone angle of 30°).
The test procedure is to start at the lowest point and the hose is worked back and forth over the test
area (typically l.Sm) for a period of 5 minutes. lt is important that any report provided to NHBC
states that a pass was achieved and not that /leak could not be observed' which means that internal
linings should not be installed at the time oftesting (or a suitable means of internal inspection
facility such as holes at set centres around the joint/opening is agreed with NHBC prior to test).
As guidance, testing of 5% ofthe fac;:ade of curtain walling is stated in the NHBC Standards applicable
to Curtain Walling systems. This% might also be applied to cladding in terms ofthe number of
junctions with windows to be tested.
Spray bar testing
This is essentially a long pipe fitted with nozzles at regular intervals (not more than 400mm centres)
along its length and provides a spray of water over the face of a cladding system. The bar is mounted
at 250mm from the face of the cladding system and has a working pressure of 2-3 Bar to achieve a
flow rate of 5 litres/minute/metre length of spray bar. Testing of one location should last for 30
minutes.
NHB00001317 _0037 NHB00001317/37
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Appendix 5. Sectional drawing examples
r,._r
t
Image from http:/ /www.aquariancladdi ng.co.uk/technical-drawings
This detail is for a GEBRIK system which has not been assessed for use on soffits. Drainage of the
15mm cavity appears to be via a director channel -exactly how this performs and interaction with other elements particularly the timber battens should be considered. Mounting and sealing around windows should be completed in line with NHBC Standards.
NHB00001317 _0038 NHB00001317/38
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Curta i er syste hor:·zon al sec ion
1n ern C I D
n
DPC/D
The following plan and section identify the need for a cavity barrier and illustrate fixings.
151-IM TIMBER BArrEN TO CREATE 15MM DAAII<Oa CAVIlY
UGHT WEIGHT STEB... fliAME sYSTEM
f-UN 12MM CLMENT PARTICLE BOARD
OR MlN l5r»1M PlY/ DSaiiOARD
INSUlATION WITijJN STEEl RIAME TO .<CHIEIIE REQUIIIED UVAI.UE
8Rl'Al>teR HEHBRAAE
Image from http:/ /www.aquariancladdi ng.co.uk/technical-drawings
SHE.<THING 60ARD
PLAN: VERTICAL JOINT
NHB00001317 _0039 NHB00001317/39
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MORTAR (APPUED TO WHOLE SYSTEM, AFTE >ll<lr'IG TO S<JilSTRATE)
MIN 12.MM CEMENir PARTla.E BOARD -~~r'c"!''l{ OR: HIN lSt., r,..t PLV/OS6 BOA~
JS>IM TIMBER BATTEN TO Ct<EATE J5"M --iJol""'=:J-'c'f-:;j'O~ . DRAINAGECAVm
GEBitiK PAliiEI..
- -·~
.a
~
4 " A . 4
~
.4 A ·
43 INSULATION
--- -~ b ..
•, A 4
. . . .. •A
4 ~
•• ~
Image from http:/ /www.aquariancladdi ng.co.uk/technical-drawings
Movement joints
M~ tlMM CEMENT PAIITlCI.£ eOo'IR.t>
OR MlM ISMM PLY I osa l!OAAD
lltSlllATION Wl"THIN illll. flW'IE TOACHif\IE llfQU!ltfl) U VWJE
Image from http:/ /www.aquaria ncladdi ng.co.uk/tech nica 1-d rawings
SECTION: HORIZONTAL JOINT
PLAN: VERTICAL JOINT
NHB00001317 _0040 NHB00001317/40
Cladding Systems
... MIN llHM Cf>lfNT PAATIQ.E llOAAO --t"""=:""'::d"'~
OR Mrn 15MP4 PlY/ OS8 !!IONt.D
.. 4
A
44 R.£)(la£ SE,.\U.Nl JOUil
.. ..... ..
4 4
.; 4 4
,jl <l •
4. •
~-~~~~----~r~~~~D UVIIU.Ie
UGHT WEUiHT STfEl FJW1[ S'YSTI:M
SECTION: li0R1Z0NTAL JOINT
Image from http:/ /www.aquariancladdi ng.co.uk/technical-drawings
Movement joints should be as specified by the design and usually follow through from movement
joints in the supporting fabric. Detailing for waterproofing ofthese joints is an area to be considered and as with other cladding types it would not be unreasonable to expect provision of a double seal.
Window head detail
NHB00001317 _0041 NHB00001317/41
Cladding Systems
Image from http:/ /www.aquariancladdi ng.co.uk/technical-drawings
Mounting and weatherproofing ofthe flashing/sill and window will be a critical interface to enable drainage to the cavity and not to permit water penetration behind the window head.
NHB00001317 _0042 NHB00001317/42
