Cavity, structural support and battens
- Ventilation cavity shall be a minimum of 21mm
- Vertical cladding battens with top edge machined at an angle will help shed water into the cavity.
- Battens need to be made from durable timber e.g. softwood pressure treated for a BSEN335:1 use Class 3 application to give a 30 year desired service life is ideal.
- Battens are normally spaced at 600mm centres.
- For high moisture content species like green oak use 400mm centres.
Timber cladding should provide adequate weather protection for the buildings. However, it must be assumed that not all wind driven rain will be deflected. As a consequence, a well ventilated, free draining cavity should always be included in the detailed design.
Whether a solid masonry or timber frame structure, TDCA recommends that this cavity shall be a minimum of 21mm wide. However, the width of cavity is generally decided by the style and width of the cladding board. The more open the cladding style the wider the cavity required to protect against moisture penetration.
On timber frame buildings, the minimum sized batten (21mm) may be used so long as its position coincides with wall studs.