Technical FAQ

I'm interested in selling wood to importers and distributors in the UK. Can the TTF help me?

Normally overseas suppliers would appoint a UK-based agent to represent their interests. Agents tend to specialise in particular regions or species and so key information to find an appropriate agent are:  What species? What source? Intended markets?



Part of the agency package would be to help suppliers understand the UK/EU market requirements and find potential buyers for their products at an appropriate price. This work would be undertaken based on an agency contract and usually in return for an agreed percentage of each sale.



The agent may also facilitate financial, contractual or importation related services where required, such as standard forms of contract, funds transfer, currency exchange, bills of exchange, insurance, freight and customs formalities.



Why has the building inspector rejected my choice of roof battens?

BS.5534 is the UK Code of Practice for slating and tiling, so good construction practice is to only use battens which are graded and marked to show they are fully compliant with this code.



I'm confused by all the different types of preservative treatments. What’s the best way to get long lasting fence posts?

TTF members are always happy to help customers choose the right product for the job, but there is a very simple system of use classes which underpins preservative treatment. Anything which will be permanently in ground contact, such as fence posts should always be Use Class 4.


Why is some of my wood marked C16?

This is a mark showing that the wood is suitable for structural applications, like joists or rafters.


In the UK we have three main strength classes:

  • C16 for most general construction uses.
  • C24 for higher strength uses like long span joists or beams.
  • TR26 for specialist applications like trussed rafters.


I used to buy WBP plywood, but my merchant tells me it’s no longer available. What should I buy now?

The replacement is a plywood described as having a glue bond meeting EN314 Class 3. This bond is strongly resistant to moisture so is suitable for all construction applications, and can be used outside when suitably coated.  Don’t forget that all wood-based panels will absorb moisture and increase in thickness especially along the edges. Therefore, all panels should be fully edge sealed to maintain their dimensions, keep them flat and give them a long life.


As a manufacturer who creates and pallets, where can I buy wood to meet the requirements of ISPM15?

This standard is one of the internationally-adopted measures to help prevent the transfer of pests and diseases between forests in different countries. It applies to manufactured wood packaging, such as pallets, or creates rather than individual pieces of wood.


As a manufacturer, you must register and participate in the scheme to show your products are compliant. TTF members will be happy to help with timber supplies once you have chosen which route within the scheme you wish to follow.


What is strength grading?

Each piece of wood must be individually inspected and marked, which means in order to be cost effective it is  usual to undertake this process at the sawmill during production.


There are two types of of strength grading: machine and visual.


Machine Strength Grading – Uses equipment such as the Goldeneye 700


Visual Strength Grading – Where trained staff visually inspect each piece of wood on a production line in order to allocate the appropriate grade such as Special Structure (SS) or General Structure (GS). This requires staff undertaking a registered training course and then putting in place a factory production control system to ensure their output is consistent. Part of this process is that each grader must be audited at the factory each year to check their performance.

How do I become C16 approved?

Whether you strength grade through a machine or visually, you will need an independent body to oversee and provide 3rd party certification on the production.

There are two main providers in the UK: CATG and BM Trada Certification.

Contact them for advise on how you start this process and what the costs are likely to be.

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