Timber Roof Wall Plate Size

Additional wall insulation may increase the depth of the frame to 125mm if the wall requires more structural strength that may increase the timber thickness from 35mm to 45mm.

Timber roof wall plate size.

The roof covering membrane may also require additional fixing using mechanical fasteners to prevent uplift high wind load areas. Minimum timber size will be 95mm x 35mm although this may increase for the following reasons. These are typically 1 2 m long with a cranked end and are fixed to the wall plate at 2 m centres. Where trussed rafter roofs are not subject to uplift a minimum of two 4 5mm x 100mm galvanized round wire nails skew nailed one on each side of the trussed rafter or truss clips fixed in accordance with the manufacturer s instructions are acceptable.

The trimmed joist will measure 600mm minus the thickness of the joist substitute 600 for 400 450 or whatever centers you are working to. Fixings used to connect the roof structure to the wall plate should be specified according to the roof construction and exposure of the site. As the mortar does not bond the wall plate to the wall steel straps are used to ensure that the roof structure remains secure. Wall plates are to be fixed to masonery using hardened nails 4mm in diameter x 75mm long or 50mm long wood screws if fixed into timber.

Generally wall plates are in lengths of not less than 3 m. 38 x 100mm or in accordance with local practice. Wall plates should be joined using half lapped joints at corners and in running lengths. Also called a wall plate raising plate or top plate an exception to the use of the term plate for a large load bearing timber in a wall is the bressummer a timber supporting a wall over a wall opening see also.

If you have tall joists you may need to cut a splice or seat cut on the end of the joist so it doesn t protrude above the rafters. Likewise for the trimmed joist 600mm from the outside of the wall plate.