Moisture Management Checklist

Solutions for the control of moisture should include:

l Consider an open panel type of timber frame structure and get it inspected frequently by the certifier during construction.

l Keep the bottom surfaces of sole plates for all external wall panels at least 150mm above the external ground level. This should include areas where the external ground rises towards entrance doors to comply with the access regulations.

l Do not fix the sole plates of internal walls in positions where they will be left sitting in a potential water channel, e.g. where a floor screed and DPM is laid up along each side of the bottom of a wall panel.

l Get the roof on and the building shell weathertight as soon as possible.

Information required by building control

Building control will require that you submit information in relation to your design. In NI they will carry out inspections during the build. Designs and specifications must be clearly understandable and include: l A full set of working drawings including drawings produced by the timber frame manufacturer. l The materials specification. l The position and materials for cavity barriers in accordance with the building regulations. l Manufacturers’ written recommendations relating to proprietary items.

The fixing schedule must accompany details of every installation) of the timber frame structure should be checked and certified by a structural engineer and/or an NHBC registered timber frame certifier, who should not be the designer of the timber frame nor be from the same practice or company. l Consider putting up a temporary roof if the building is to be left exposed for prolonged periods in bad weather. The cost might be less expensive than the cost of remedial work. l Build the timber frame during dry weather. I know, that’s easier said than done, but if at all possible, try to make it happen. l Allow all wet timber including wood based panel products, to dry out properly before covering them. l Monitor the moisture content of all timber, wood based panel products and the insulation. The moisture content should be stable at less than 20 per cent before closing up any timber frame panels. Remember that water runs down, so timber at the bottoms of panels will probably be wetter than the timber above. Also, wood based panel products can retain moisture for longer than solid timber. l Use temporary membranes to keep out water ingress where possible and to protect sensitive materials during construction works. These might include wood based panel products such as OSB and plywood, all membranes, plasterboard, insulation, etc. l Don’t allow trades to nail through or otherwise make holes in the VCL or VPM. l Ensure that differential movement measures are built in accordance with the detailed drawings.

The certifier should complete and sign a certificate confirming assessment of structural adequacy for each specific project and give a copy to the builder and to building control.