BS 644:2012 pdf download – Timber windows and doorsets – Fully finished factory-assembled windows and doorsets of various types – Specification
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.
5.2.1 Timber/aluminium composites If aluminium extrusions are used as cladding or part of the window or doorset frame, they shall be fabricated from designated alloys EN AW-6060 or EN AW-6063 in tempers T5 or T6 conforming to BS EN 755-2:2008 and BS EN 755-9:2008 or BS EN 12020-1:2008 and BS EN 12020-2:2008. They shall be finished by anodizing conforming to BS 3987 or BS EN ISO 7599, with a liquid organic coating conforming to BS 4842, or by a powder coating conforming to BS 6496 or BS EN 12206-1.
There shall be no direct contact between mill finish aluminium and oak, sweet chestnut or western red cedar, as the acid content in the timbers can damage the aluminium. NOTE For a full description of the requirements for the selection, fabrication and installation of aluminium windows and doorsets, see BS 4873.
5.2.2 Composites with other materials Composite materials other than aluminium shall have suitable durability for use as an external element when assessed using the relevant clauses from the appropriate window and/or doorset product standards and related material standards [e.g. BS EN 12608 and BS 7412 for unplasticized polyvinyl chloride (PVC-U)].
NOTE Guidance on the suitability of different types of finish for various locations and environments is given in BS 6150.
5.3 Adhesives Adhesives shall meet the requirements of BS EN 204:2001. The class of adhesive shall be not less than BS EN 204:2001, type D3 for concealed or semi-concealed joints or type D4 for exposed joints. 5.4 Glass Glass thickness and type shall be selected using the recommendations given in BS 6262-1, BS 6262-2, BS 6262-3, BS 6262-4 and/or BS 6262-7, as appropriate, to withstand the design wind pressure calculated in accordance with BS 6375-1 or BS EN 1991-1-4.