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Architects,
Designers & Specifiers

Hanson Plywood offer a full and comprehensive guidance service to ensure that correct products are used for all applications. The information on panel products can be quite limited in many educational courses relating to architecture and design. This is why we are happy to provide assistance with specification for any end use.

All of our sales staff specialise in wood based panel products and are Technicians in Wood Science as recognised by the Institute of  Materials, Minerals and Mining (IOM3). In addition to this, the company is a member of TRADA and keeps abreast of all changes to standards and regulations that affect the specification of wood based panel products in structural design. You can find further information on product standards on our Knowledge Base page.

New RIBA Approved CPD

Hanson Plywood is proud to form part of the Approved RIBA CPD Providers Network offering a unique and informative CPD entitled:

‘PLYWOOD: A DEFINITIVE GUIDE TO SPECIFICATION’

This CPD forms part of the RIBA Core Curriculum programme and offers architects, specifiers and designers the opportunity to gain more in-depth knowledge relating to the manufacture and selection of plywood as a construction product in line with European Standards leading to more informed specification.

The seminar focuses on:

  • The key features and origination of plywood within a global context.
  • The legal and environmental framework that impacts on plywood specification.
  • The key aspects and variability of the plywood manufacturing process.
  • The origination of Marine Plywood and the disconnect with current European Plywood Standards.
  • The European Technical Standards that underpin robust plywood specification.
  • The key features of the different birch plywood face grades available.
  • Reaction to Fire European Standards applicable to plywood.

FAQ’s

  • This lunchtime seminar will last 50-60 minutes which includes time for Q&A’s.
  • Double CPD points are awarded to attendees.
  • Certificates of Attendance are issued upon completion of the seminar.

To book a CPD please call 01422 330444 and talk to our Product Specification Advisor.

Advice on Specification and Treatment of Exterior Plywood

Exterior in service, in building terms, covers a wide range of situations from full and severe exposure (sign boards, sea font fascias) to sheltered and protected (soffits under porches and balconies). There are also applications other than in buildings that impose similar stresses on plywood in service.

Two different exterior situations where plywood has a long history of sucessful use can be recognised.

  • Exterior but not protected- where direct wetting of surfaces and edges is unlikely once construction is completed. Applications such as this (sheathing, soffits, roof decking, etc.) are designated as ‘Use Class 2’ according to BS EN 335:2013 (‘Durability of wood and wood-based products- Use Classes: definitions, application to solid wood and wood-based products’). In Eurocode 5 (EN 1995-1-1) and structural design terminology, these applications would be more closely aligned to the in-service, environmental conditions expected of Service Class 2. Applications  such as these would require plywood that is suitable for Humid Conditions that meets EN 636-2.
  • Full exposure to weather (charcterised by the possibility of high moisture content in service, driving rain and full exposure to sunlight). Examples include cladding, fascias, exterior doors and more. These situations fall under Use Class 3 under BS EN 335:2013, and in most cases would meet the environmental conditions of Service Class 3 under Eurocode 5. Plywood that meets the requirements of EN 636-3 for use in Exterior Conditions is appropriate for these uses.

The factors of exterior exposure that can be significant to the performance of plywood are:

  • Rain (particularly wind-driven) and where drying-out is slow.
  • Fluctuations in relative humidity.
  • Sunlight, particularly on south-facing aspects and dark coloured surfaces.
  • Fungal organisms.
  • Frost, insect attack and sever chemical pollution may sometimes also have an adverse effect on the service life of plywood.

Rain, either wind-driven or running down the facade of a building, can be rapidly absorbed by unprotected end grain of timber.

Plywood contains much end grain around the edges which must be protected if satisfactory performance is to be achieved. If the edges are not protected, water can enter and give rise to stresses which can eventually cause splitting of the wood and separation of the veneers around the edges even of ‘exterior’ bonded panels. In the shorter term, it often gives rise to unsightly staining behind a finish and can lead to mould growth, blistering of paint and ultimately decay.

it is, therefore, imperative that the edges of all panels are protected if satisfactory performance can be achieved.

Water usually penetrates much more rapidly than is lost. This is particularly the case if its entry is localised, such as through an area of improperly applied edge sealant. Under these conditions, water can be trapped for long periods behind fairly impermeable finishes, putting considerable demands on the durability or preservation treatment at the plywood and the adhesion of the finish.

 

EN 636 : 2012 + A1 : 2015 Plywood-Specifications

Plywood manufactured for construction purposes is specified in accordance with EN 636. Products claiming compliance with this standard must also carry the specified markings, which includes a reference to EN 636. This standard was originally in three parts, but was reissued in a single part as follows:

The most recent edition of EN 636 retains the designations -1, -2 and -3 from the previous three part standard to represent dry, humid or exterior conditions of use.

These conditions are defined according to the parameters laid down for Use Classes in BS EN 335 durability of wood and wood-based products. Use classes: definitions applicable to solid wood and wood-based products.

Dry conditions: For interior applications with no risk of wetting, defined in Use Class 1, with a moisture content corresponding to environmental conditions of 20°C and 65% relative humidity.

Humid Conditions: For use in protected exterior applications as defined in Use Class 2, with a moisture content corresponding to environmental conditions of 20°C and 85% relative humidity.

Exterior Conditions: For use in external applications, as defined in Use Class 3, where the moisture content will frequently be above 20%

 

EN 636 also introduces bending strength and modulus classes based on bending tests to EN 310. These give a designated strength (F) and modulus (E) parallel and perpendicular to the face grain. An example designation would therefore be F10/20. E30/40.

EN 636 gives minimum values for each of the classes and EN 12369-2 gives corresponding characteristic values for use with each of these classes.

Plywood for use in construction must demonstrate compliance with the Construction Products Regulation (CPR). The most straightforward route to achieving this is by demonstrating compliance with EN 13986, and therefore must carry a CE mark.

The properties required of panels in EN 636 are shown in the clickable PDF link below:

Properties of panels in EN 636

 

Glue bond: Classification

Plywoods are produced with glue bonds which range from those suitable for interior uses only, to those which will withstand full exposure for long periods.

BS EN 314-2 Plywood bonding quality. Requirements define three classes on the basis of test requirements that the plywood must meet:

Class 1: Dry conditions (interior, dry uses).

Class 2: Humid conditions (protected external service, ‘damp’ internal uses and limited exposure during construction).

Class 3: Exterior conditions (exposure to weather over substantial periods or continuous exposure to relative high humidity).

Full Exterior Bonding 

Class 3 bonds are a requirement for plywood to comply with BS EN 636-3. The bonds are largely comparable with what were known as WBP- weather and boil-proof bonds (to BS 6566 Part 8, now withdrawn), expect that the requirement that effectively they be made with phenolic-type glues has now been dropped. To qualify, the bond must now meet the stipulated test requirements.

Quick Reference Guide - OSB
Type
Application & Climatic Conditions
Use Class (EN 335)
OSB/1
Non-Structural, interior fitments including furniture
Use Class 1
OSB/2
Internal, structural applications
Use Class 1
OSB/3
Structural applications similar to those listed above, however OSB/3 is is suitable for use in humid conditions
Use Class 1 & 2
OSB/4
Heavy-duty structural applications in humid conditions
Use Class 1 & 2
Quick Reference Guide - MDF
Trade Term
Class
Typical Average Density
Application & Climatic Condition
Use Class (EN 335)
General purpose joinery
Simple designs with minimal profile
Humid Conditions
Architectural mouldings - skirting architraves
Deep routed profiles (e.g. membrane pressed PVC doors)
Designs with advanced deep routed profiles and painted finishes
Standard
MDF
650 Kg/m3
General purpose boards for dry conditions
Use Class 1
Yes
Yes
Yes
Trade
L.MDF
625 Kg/m3
Light MDF boards for dry conditions
Use Class 1
Yes
Yes
Ultralight
UL2.MDF
520 Kg/m3
Ultra-light MDF boards for dry conditions
Use Class 1
Yes
Yes
Moisture Resistant
MDF.H
720 Kg/m3
General purpose boards for humid conditions
Use Classes 1 & 2
Yes
Yes
Yes
Yes
Exterior
MDF.H-2
770 Kg/m3
General purpose boards for exterior conditions
Use Classes 1,2 & 3
Yes
Yes
Yes
Yes
Yes
Yes
Quick Reference Guide - Chipboard (Particleboard)
Type
Application & Climatic Conditions
Use Classes (EN 335)
P1
Internal, non-structural applications
Use Class 1
P2
Internal, non-structural furniture items
Use Class 1
P3
Non-structural applications similar to those listed under P2 above. However, P3 is suitable for use in humid conditions
Use Classes 1 & 2
P4
Internal, structural applications
Use Class 1
P5
Structural applications similar to those listed under P4 above, however P5 is suitable for humid conditions
Use Classes 1 & 2
P6
Heavy-duty internal structural applications
Use Class 1
P7
Heavy-duty structural applications in humid conditions
Use Classes 1 & 2
Quick Reference Guide - Plywood
Applicable Products
Typical Applications
Use Class (see definitions)
Applicable Standards
Minimum Requirements
Internal applications with minimal exposure to moisture.
All internal joinery, flooring underlay, pipe boxing, doors, hatches, weight saving applications etc.
Internal joinery with temporary exposure during construction.
Flooring, walls, roof decking, linings, hoardings, protection etc.
All internal and external joinery which may be submitted to long term exposure to wetting/weather.
Construction - Floors, walls, roof decking, soffits, linings, signs etc
1 - Dry
2 - Humid
3 - Exterior
EN 13986 - Wood-based panels for use in construction
EN 636:2012+A1:2015
Plywood specifications
EN 314-2 - Plywood bond quality
EN 310 - Bending test
EN 13986 - Wood-based panels for use in construction
EN 636:2012+A1:2015
Plywood specifications
EN 314-2 - Plywood bond quality
EN 335 - Durability of wood and wood-based panel products
EN 310 - Bending test
EN 13986 - Wood-based panels for use in construction
EN 636:2012+A1:2015
Plywood specifications.
EN 314-2 Plywood bond quality
EN 335 - Durability of wood and wood-based panel products
EN 310 - Bending test
CE Marked
Class 1
Class 1
Refer to test data
CE Marked
Class 2
Class 2
Class 2**
Refer to test data
CE Marked
Class 3
Class 3
Class 3**
Refer to test data

In order to assist Architects, Specifiers & Designers we have developed our specialist plywood panel range which includes products that have very specific manufacturing and performance criteria. All these products carry the appropriate certification for industry, and can be confidently specified for a vast range of applications.

We have also launched a comprehensive advisory service website and printed document titled ‘The Plywood Specifiers Guide’ for architects, designers & specifiers in the specification and uses of plywood products in all applications.

Downloads & Links

OUR SPECIALIST PLYWOOD RANGE