Finishes for external timber

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Timber that has no protective finish will often weather to an attractive appearance. However, in many situations, it is necessary to specify a protective finish. Appearance is often the main reason for specifying a finish, but other characteristics are important too.

The technology behind protective finishes moves rapidly and the range of generic types and manufacturers' variants is bewildering. Deciding whether to specify preservative, paint, varnish or stain is just the start.

This Wood Information Sheet (WIS) outlines the need for finishes, the different types of finishes as well as the performance of the various finishing types, helping specifiers to select the correct finishing coat for the job.



  • The need for finishes
  • Types of exterior finish
  • Considerations for hardwoods
  • Considerations for panel products
  • Selection of coatings
  • Common coating faults and how to avoid them


This Wood Information Sheet was reviewed in March 2020. Minimal amendments have been made to update the references.

Suggested Reading

Preservative treatment for timber - a guide to specificationnavigation-arrow

The first decision to be made regarding preservative treatment is whether the use of a naturally durable species will satisfy the durability requirements or whether treatment is needed. This Wood Information Sheet aims to guide the specifier through the process necessary to reach a decision that will result in a...

25/03/2021 |  Wood Information Sheet  

Timber windows and conservatories: Fact sheet no. 5navigation-arrow

This wood for good fact sheet gives a brief overview of timber windows and conservatories including specification details, the benefits of timber windows (including their compliance with Part L Building Regulations) and the various finishes and treatments available for timber windows.


  • Specifications
  • Species
  • Benefits
  • Accreditation schemes
  • ...

01/01/2004 |  Info from other organisation  

List of Wood Information Sheetsnavigation-arrow

This document contains a fully comprehensive list of all the most up to date Wood Information Sheets (WIS) published by TRADA. Available to members for free or non-members for £12.00, these Wood Information Sheets provide technical guidance related to almost every timber topic under the sun.



  • Timber -...

22/03/2021 |  Wood Information Sheet