Windows and Doors

Windows and doors provide so many critical attributes to a building, many of which we take for granted: aesthetics, weather protection, fire resistance, sound reduction, security and more besides.


Using our FAQs, simple guides and books below, let us help you understand how to correctly specify and choose the right products for each project.


For testing, third-party certification, inspections and training on doors and window, call our technical helpline on +44 (0)1494 569601.  All commercial services are provided by TRADA’s service provider, BM TRADA.

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What finishes are recommended for timber external doors?

Factory painted doors and frames supplied as doorsets are the best solution.

However, if finishing on site, apply a protective finish on delivery and after erection. Finishing treatments for external timber doors are not simply decorative but play a vital role in the long-term performance of the door.

High-build exterior stains and good-quality exterior paints are suitable finishes. Avoid thin penetration seals, oils or stains and hard, brittle paints or varnishes and always follow the manufacturer's recommendations for the application of finishes.

Manufacturers/assemblers of complete window and external doorsets (that are not fire, smoke or emergency escape doors) need to comply with the EU Construction Products Regulation (CPR), which means meeting the requirements of the Product Standard BS EN 14351-1:2006+A1:2010: Windows and doors - Product standard, performance characteristics - Part 1: Windows and external pedestrian doorsets without resistance to fire and/or smoke leakage characteristics.

This means that windows and external pedestrian doorsets must have a CE Mark and a Declaration of Performance (DoP).

To minimise the moisture movement of the timber components of an external pedestrian doorset, consider the following:

  • Understand the behaviour of timber in response to changes in moisture content
  • Design the doorset to accommodate moisture related movement
  • Specify a small movement timber
  • Specify at least a 3mm clearance around doors to allow for movement
  • Protect the doorset from extreme weather conditions with a canopy or porch
  • Use multi-point locking to prevent distortion of the door leaf
  • Maintain the moisture content of doorsets during storage through appropriate protection and conditioning.

  • Design windows to be recessed sufficiently into the surrounds to provide weather protection and ensure continuity of thermal insulation between window and wall.
  • Provide sufficient detail in the case of bespoke windows to indicate the general appearance required, but not so much that a window manufacturer cannot incorporate their own tested detail profiles into the design.
  • Require compliance wherever possible to British or European standards, covering not only the frames but also the glazing, finishes, weatherstripping, and ironmongery.
  • Ensure that your specification includes sufficient criteria, covering wind loading, thermal insulation, security, weather resistance, background ventilation etc for the window manufacturer to be able to take on full design responsibility.

Refer to Wood windows: designing for high performance for further guidance.

  • Specify a fully ventilated/drained method for installing insulated glass units preferably with external beading.
  • Specify that windows are to be fully factory finished, and either factory glazed or that the glazing remains the responsibility of the window supplier, even if, for practical reasons, glazing must be carried out on site.
  • Specify that windows are to be installed into preformed openings (not built in), ensuring that sufficient clearance between frame and surround is provided to allow for building tolerance, efficient airtight weathersealing and insertion of adequate insulation to prevent thermal bridging.

Refer to Wood windows: designing for high performance for further guidance.

  • Wood window frames will require redecorating at some stage, unless they are of unfinished hardwood or faced with aluminium. Recoating must take place before the existing finish has deteriorated to the extent that bare wood is exposed to UV light.
  • Insulated glass will eventually need replacing because the seals will fail, allowing condensation to develop.
  • Weather stripping, particularly foam cored or tubular compression seals, will lose elasticity and become less efficient over time.
  • Specifying corrosion resistant hinges and other hardware should ensure a long service life; regular cleaning and lubricating may help ensure efficient long term performance.
  • Nowadays many factory-finished windows come with a warranty on the paint finish. Check with your supplier to see if this applies, and what is recommended for maintenance.
  • Obtain a technical description of the windows, including supplier contacts and recommended maintenance from the manufacturer or installer.

Wood windows: designing for high performance provides further information on these considerations.

TRADA membership

As a member of TRADA you can enjoy free access to our entire online collection of technical guidance on not only decking but all other construction related topics.

You can also use our Technical Helpline (01494 569601) for free at any time during office hours. (Please note that advice is limited to 30 mins per call. Commercial consultancy by BM TRADA can also be provided where written or professional opinion is required on specific products or projects.)


Introductory guidance

You can register for free and download some of the guidance below:


Comprehensive guidance / books

Wood windows: designing for high performance, (online edition for members only or available in our bookshop).



We run introductory and intermediate training courses on a range of timber topics.

In-house courses can also be provided.


Consultants and commercial services

BM TRADA is able to provide a wide range of commercial services including product testing, certification, CE marking, and product design advice.