This guide explains the different Use Classes normally associated with treated timber
Guide to Treated Timber Use Classes in the UK
What Are Timber Use Classes?
In the UK, treated timber is classified into Use Classes based on its level of treatment and the environment in which it will be used. These classifications help determine the durability and suitability of timber for different applications.
The Five Use Classes Explained
|
Use Class |
Description |
Common Applications |
|
UC1 |
Indoor, dry conditions |
Furniture, flooring, interior joinery |
|
UC2 |
Indoor, occasional moisture |
Framing, beams, structural timbers (not exposed to weather) |
|
UC3 |
Outdoor, above ground |
Cladding, fencing, decking (not in contact with soil) |
|
UC4 |
Outdoor, in contact with the ground |
Fence posts, sleepers, decking supports, utility poles |
|
UC5 |
Marine and freshwater exposure |
Harbour structures, piers, marine piles |
Choosing the Right Use Class
- For interior projects, Use Class UC1 or UC2 is usually sufficient.
- For external timber (not in ground contact), Use Class UC3 is recommended.
- For timber touching the ground, like fence posts, always choose UC4 to prevent rot.
- For marine environments, Use Class UC5 is essential due to constant water exposure.
Key Takeaways
- Use Classes ensure the right level of treatment for different environments.
- Choosing the correct class helps prevent decay, rot, and insect damage.
- Always check the timber treatment certification when purchasing.