Substrates - Timber Boards
New timber boarded roof deck in accordance with the current standards. Boarding should not be less than 25mm nominal thickness, planed and clamped together with tongued and grooved joints or closely butted and secured by ring shanked nails or screws at a rate of 2 per board width at both ends and at every intermediate support. Fixings should be well driven to avoid damage to the membrane.
Good roofing practice requires the roof to be free of significant ponding within 48 hours of rainfall. Where the structural deck does not provide drainage or removal of standing water within 48 hours, the substrate should be corrected to provide positive drainage.
It is recommended that all decks in a warm roof construction be sealed prior to installing the roofing system to prevent air infiltration beneath the membrane. Sealing the deck is accomplished by installing a vapour control layer over the deck and sealing around all penetrations.