BS 644:2012 pdf download – Timber windows and doorsets – Fully finished factory-assembled windows and doorsets of various types – Specification

BS 644:2012 pdf download – Timber windows and doorsets – Fully finished factory-assembled windows and doorsets of various types – Specification 5.1.2 Preservation The wood or wood-based components of a window or doorset shall either have sufficient natural durability, or be preservative treated. NOTE 1 The sapwood of any species will require preservative treatment. The natural durability of wood or wood-based components of a window or doorset to be used without preservative treatment shall be at least durability class 3 as defined in BS EN 350-2:1994. NOTE 2 If it is desired to use a species not listed in BS EN 350-2:1994, its durability can be established in accordance with BS EN 350-1. Where the natural durability of the wood is class 4 or class 5 as defined in BS EN 350-2:1994, or where sapwood is present: a) for preservatives for use in penetrating processes achieving the efficacy criteria for use class 3 coated in BS EN 599-1:2009, Table 3b, option 2, the wood shall be preservative treated in accordance with BS 8417. For other preservatives listed in BS 8417 as suitable for use class 3 coated, the wood shall be preservative treated in accordance with BS 8417; b) for preservatives for use in superficial processes achieving the efficacy criteria for use class 3 coated in BS EN 599-1:2009, Table 3a, option 3, the wood shall be preservative treated so as to achieve a penetration class NP1 (BS EN 351-1:2007) and a retention requirement of 1.5 times the critical value. For field testing to BS EN 330, the preservative shall be applied using the manufacturer’s proposed method of application, and the reference preservative shall be applied by double vacuum. The preservative process shall be such as to provide a minimum desired service life of 30 years. Any component or part of a component that is machined in a manner that exposes untreated timber shall receive further treatment to ensure the continuity of the preservative envelope. NOTE 3 The long-term performance of a window or doorset depends not only on the maintenance of the preservative envelope but on the maintenance of the window or doorset as a whole (see Clause 9). NOTE 4 Further information regarding the adjustment factors applied to the critical value and the additional tests for efficacy can be found in BS EN 351-1:2007, 5.3 and BS EN 599-1:2009, 5.2. 5.2 Composites 5.2.1 Timber/aluminium composites If aluminium extrusions...