Wood Sheets

CHOOSE AND USEUP-TO-DATE INFORMATION FOR BUILDERS

Wood-based sheetmaterials

Making the right choiceTo comply with Building Regulations it is essential you choose the

right type of timber or timber product. Look also for certification

markings (i.e. FSC or PEFC) to show timber is from legal and

sustainable sources.

For structural applications you must use structural grades of sheet

materials, appropriate for their end use. In domestic situations the

critical areas are usually in roofs, walls and floors, but structural

sheet materials may also be required in the construction of other

structures too.

When selecting sheet materials,

you need to ensure the product is

suitable for the job. You also need

to take into account non-structural

characteristics, like appearance,

moisture resistance, and fire

resistance.

Building Regulations require all timber sheet materials specified for

use in construction to be fit for their intended use and for the

conditions they will be used in. They must comply with the

Construction Products Regulations and the most common way to

achieve this is through compliance with BS EN 13986. The CE marks

on sheet materials are linked to this standard.

Sustainable timberTimber is the most sustainable building product available. It is

naturally renewable – over 97% of softwood timber used in the

UK comes from Europe, where the forest area is increasing by the

equivalent of 100 football pitches an hour.* For reassurance for

softwoods and hardwoods look for certification labels like FSC

(Forest Stewardship Council) or PEFC (Programme for the

Endorsement of Forest Certification).

*IIED & ECCM, Using Wood to Mitigate Climate Change, 2004 and MCPFE/UNECE-FAO State of Europe’s Forests, 2003.

Sheet materials aremanufactured from solidtimber and/or from recycledtimber with the addition ofan adhesive.

The most commonly usedsheet materials are plywood,Oriented Strand Board (OSB)particleboard (chipboard) andfibreboard (MDF – mediumdensity fibreboard).

These materials are widelyused in construction, with different grades fordifferent uses.

Using the right product forthe job is essential. Thisinformation sheet describesthe most commonly usedsheet materials and some oftheir applications.

This information sheet provides general advice only and is not specific to the requirements of a particular building project. It is the builder’s responsibility to check compliance withbuilding regulations and standards. © TRADA Technology and wood for good.

Produced by TRADA, the Timber Research and Development Association (www.trada.co.uk) in conjunction with wood for good (www.woodforgood.com)

Types of wood-based sheet materials

2

The following descriptions are accompanied by

a more comprehensive table of applications and

conditions of use, as well as appropriate standards.

OSB (Oriented Strand Board)Consists of resin-bonded sheets made up of small,

thin strands of wood, compressed into layers to form

a mat. It has good dimensional stability and no knots

or voids in the structure. Different grades and

thicknesses suit each use depending on the strength

required for the particular structural application.

OSB has good strength properties and is low cost.

Particleboard (chipboard)Consists of chips compressed together with resin.

Has smooth surfaces without knots or voids.

Usually available for structural and non-structural

applications. Most chipboards incorporate some

recycled chipped timber.

PlywoodPlywood is a versatile sheet material. Softwood

plywood is usually made from European grown

Spruce, whilst Birch is a common hardwood plywood.

Spruce is less decorative than Birch and is used in

construction where a visual appearance is not so

important. Birch plywood can have a clearer, knot

free appearance, depending on the grade selected.

Both plywoods have grades to suit decorative needs.

Hardwood or hardwood faced plywood is usually

produced in the Far East, South America and China*

and is generally darker in colour than softwood

plywood. (* China now produces plywoods made

from Russian Spruce and Birch, as well as Radiata pine

from New Zealand and veneers from South America).

Plywood used in formwork

Appearance and strength are less of an issue here

although durability, glue bond performance and

resistance to decay may have to be considered.

Suitable sheets are available from Scandinavia,

North America and the Far East.

Structural plywood

All plywood for structural load bearing applications

(i.e. walls, floors and roofs) must be strong enough

for the loading. Always use plywoods that are listed

in BS 5268-2:2002 – typically those from Canada,

Finland, Sweden and the USA. They need to also



3

comply with the Construction Products Regulations

(CPR) by meeting the requirements of BS EN 13986,

or by other means. The CE mark demonstrates CPR

compliance and that those structural plywoods are fit

for a particular purpose.

Marine plywood (certified to BS 1088)

Although clearly intended for wet applications,

marine plywood is not suitable for general structural

applications unless it has been tested and shown to

meet the requirements of BS EN 13986.

MDF (Medium Density Fibreboard)An engineered, stiff, flat sheet. Knot free, made from

wood fibres. It has no surface grain and can be

machined, drilled, cut and filled easily without

damaging the surface. Also available in finished

product e.g. skirtings, architraves and other mouldings.

Fire rated and external grades are available. MDF is

sometimes colour coded by dyes in the board layers

to indicate its use:

Green – for moisture resistant

Grey – for exterior use

Red – sheets with flame retardant chemicals

If used in construction MDF must comply with

Construction Products Regulations (see table

on page 4).

HardboardMade from wood fibre extracted from chips or

pulped wood waste. Non-structural for internal use

such as flooring, underlay and shopfitting, although

enhanced performance hardboards can be used

where higher strength is needed. Enhanced boards

find applications as components within structural

members e.g. I beams, exterior soffits and signage.

Blockboard and laminboardMade up of a core of softwood strips up to 25mm

wide, placed edge to edge, sometimes sandwiched

between softwood or hardwood veneers and glued

together under high pressure. Mainly used for

non-structural internal applications.

StoringStore sheet materials flat, on bearers or in ‘A’ frames.

As wood is sensitive to changes in moisture, try to

acclimatise any wood product to the temperature

and humidity in the room where it will be installed,

for a few days only.

FixingsSecure by screws, nails and glues, using the many

different specialist products developed for these

products. Metal fixings such as screws and nails

should be long enough to allow about 20mm

penetration into the substrate, or to have an overall

length of about 2.5 times the sheet thickness. Where

engineering design requires a certain fastener type

and spacing, this must be adhered to.

1234 - CPD - 5678Any company

PO Box ??Any TownCountry

02

EN 13986

EN 636-2

E1Plywood for use as structural flooring

CE logo

No of Notified Body - Directive - Product/Certificate of Conformity No

Manufacturer’s name and address

Year CE mark affixed

Harmonised European Standard

Plywood standard for humid conditions

Formaldehyde class

Intended end use application



4

Choose and Use is a series of information sheetsfor builders produced by TRADA, The Timber Research andDevelopment Association.

They offer up-to-date advice on how to select the righttimber and timber products for different applications.

You can often save time and money by choosing thecorrect timber material or timber products as well asensuring you comply with current Building Regulationsand Building Codes. For more information about specific products visit www.trada.co.uk or contact your local supplier.

For further information on all the sheet materials, specifications, sizes and thicknesses, fixing locations, support details and

spans, especially in structural applications, ALWAYS refer to the manufacturer’s own literature or website or enquire through

your local merchant. Visit www.trada.co.uk, www.woodforgood.com or the Wood Panel Industries Federation

www.wpif.org.uk/panelguide.asp for additional advice.

PRODUCT

OSB/2

OSB/3

Type P1

Type P2

Type P3

Type P4

Type P5

Complies with BS EN 636 1G



Complies with BS EN 636 3S

Complies with BS EN 636 3S

Type MDF

Type MDF H

Exterior MDF

Type HB


USES

Exhibition panels, internal walls, shelving, sitehoardings, packing, cases, garden sheds

Timber frame structural sheathing, flat andpitched roofs, wall sheathing, flooring, caravans

Standard grade, general purpose joinery &furniture

Furniture grade, usually with melamine ordecorative veneers. Kitchen and bedroomcabinets, shelving

Moisture resistant, uses similar to above

Flooring applications, loft planks, bathrooms

Flooring applications, kitchens, bathrooms

General purpose joinery

Fascias, site hoardings

Soffits

Cladding, walkways

Flooring, wall sheathing, roof sarking

General purpose, joinery, shop fronts, signage,door parts, fascias

General purpose, joinery, kitchens, bathrooms

General purpose, joinery, shopfitting, signage,door parts, fascias

General purpose, panelling, boxing in pipework

General joinery, door blanks, shopfitting

STANDARDS

BS EN 300:1997

BS EN 300:1997

BS EN 312:2003

BS EN 312:2003

BS EN 312:2003

BS EN 312:2003

BS EN 312:2003

BS EN 636:2003, BS EN5268 part 2, Eurocode 5, BS EN335 2&3 (Useclasses), BS EN 635(surface appearance)

As above, with glue lineto BS EN 314-2 class 3


As, above with glue lineto BS EN 314-2, class 3BS EN 1099 Durability


BS EN 622-5:1997

BS EN 622-5:1997

See manufacturer’sliterature orwww.wpif.org.uk

BS EN 622-2:1997

BS EN 314-2 class 1

CONDITIONS

Dry situation, structuralapplications

Load bearing use in humidconditions

Dry interior use, not structural

Dry interior use, not structural

Interior use, not structural

Dry interior use, structural

For use in humid conditions,structural


Exterior use in humidconditions, not structural.Take into account durabilityof surface species BS EN 635

As above

Fully exposed, exteriorconditions above ground, notcovered, structural

Covered, above ground,structural, semi exposed

Dry conditions, interior usenot structural

Humid conditions,not structural

Exterior conditions, for moreinformation seemanufacturer’s details



USE CLASSES (where applicable)

Class 1

Class 1 & 2

Class 1

Class 1

Class 1 & 2

Class 1

Class 1 & 2

Class 1 dry conditions 20%-65% relative humidity

Class 3 moisture level 20%+,above ground, uncovered

Class 1 & 2

Class 3 exterior conditionsabove 20% moisture level. Class 1 & 2

Class 1 & 2 risk of wetting,humid conditions, 20-90%relative humidity

Class 1

Class 1 & 2

Class 1, 2 & 3

Class 1

Class 1

OSB (Oriented Strand Board)

Chipboard

Plywood

MDF (Medium Density Fibreboard)

Hardboard

Blockboard / Laminboard


Documents

Wood Sheets