2.3 Timber preservation (natural solid timber)
|2.3 - D1||Design standards|
|2.3 - D2||Statutory requirements|
|2.3 - D3||Durability|
|2.3 - D4||Method of treatment|
|2.3 - D5||Compatibility with metal components|
Design that follows the guidance below will be acceptable for timber selection and preservation.
Design should be in accordance with relevant Building Regulations and other statutory requirements
Timber and external joinery should be either:
- naturally durable and resistant to insect attack, or
- treated with preservative in accordance with this Chapter.
Appendix 2.3-A provides information to establish whether or not treatment is necessary for a particular element or timber species and also the type of treatment.
For timber or joinery which requires treatment, it is important that it is carried out to appropriate standards which are both suitable and safe. Treatments in accordance with procedures set out in British Standards, Codes of Practice or which have been satisfactorily assessed by an independent authority, will be acceptable, unless otherwise notified in writing.
Where copper/chromium containing preservatives (CC, CCP or CCB) have been used, it is important that metal fittings are not applied to the timber until the salts of the treatment have been "fixed" (7-14 days). In situations where occasional dampness is expected, metal fittings in contact with timber treated with copper containing preservatives should be galvanized. Where timber treated with copper containing preservatives is likely to become wet, fittings of austenitic stainless steel should be used.
Copper containing treatments can create a corrosive cell between mild steel and aluminium.