A system based on storey height factory assembled structural timber wall panels used in conjunction with either a concrete ground floor or a ‘timber platform’ ground floor and ‘timber platform’ intermediate floors. The intermediate ‘platform floor’ extends over and is connected to the head of all storey height panels to create a rigid structural ‘box’. The top storey will also be so connected by the timber roof construction which may be flat (like the floor construction) or pitched (typically timber trussed rafters). The external wall panels comprise a frame of vertical softwood timber studs (at 400mm – 600mm centres) + base plate and head plate and intermediate noggins. The panels have a structural sheathing of either plywood or OSB board securely nailed to all the framing members to provide ‘racking’ resistance. External wall panels are protected with a breather membrane which provides temporary weather protection during construction and long term protection in the event of any leaks through the external cladding. Insulation is fitted to wall panels between the softwood studs. A vapour control layer is fitted internally behind the plasterboard finish to prevent interstitial condensation.
Limits on scope:
- Maximum 5 storeys
- Bottom timber members must be minimum 150mm above external ground level and preservative treated
- External wall claddings, including masonry, must have a drained and ventilated cavity
- Every structure must be designed by a structural engineer
- Provision must be included for differential movement between the timber frame (which shrinks as it dries) and independent rigid elements such as external brickwork, concrete stairs shafts and steel lift shafts etc.