BS 644:2009 pdf free download – Timber windows – Fully finished factory-assembled windows of various types – Specification.
NOTE This is sometimes called a weatherstrip.
4 Window handing
The handing shall be in accordance with the specification provided. Where the manufacturer is specifying the handing, the specification shall conform to Annex C.
NOTE 1 Where the manufacturer is not specifying the handing, care should be taken to check the handing designation. See Annex C, Note to C. 1.
NOTE 2 Further advice on window specification is given in Annex D.
5 Components
5.1 Timber
5.1.1 Quality
Timber shall be of a species classified as suitable for its purpose in accordance with BS EN 942:2007, National Annex NA. The timber for window frames, casements and sashes shall be of the classes defined for the UK in BS EN 14220, or better.
NOTE Where for reasons of design or appearance a higher quality of timber is required, the specifier should discuss these special requirements with the manufacturer in respect of timber species and availability.
5.1.2 Preservation
The wood or wood-based components of a window 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 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, its durability can be established in accordance with 85 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 assessed under BS EN 599-1 for penetrating processes and other preservatives listed in BS 8417 as suitable for Use Class 3 (as defined in BS EN 335-1:2006), the wood shall be preservative treated in accordance with BS 8417 (Use Class 3.1, 30-year life);
b) for preservatives assessed under BS EN 599-1 for superficial processes, the wood shall be preservative treated using a preservative with a critical value (CV) derived from BS EN 599-1:1997 3), Use Class 3 (with coating), including testing to BS EN 330, in which the preservative shall be applied using the manufacturer’s proposed method of application and the reference preservative shall be applied by double vacuum. The treatment shall achieve penetration class P1 (BS EN 351-1:2007) and a retention of CV (factor x 1.5).
Any component, or part of a component, that is machined in a manner that exposes untreated timber shall receive further treatment to ensure continuity of the preservative envelope.
NOTE 3 The long-term performance of a window depends not only on the maintenance of the preservative envelope but on the maintenance of the window as a whole (see Clause 9).