Fixing plywood sub-floors to concrete slabs and flooring to plywood
• Slabs should be level to ± 3 mm in 1.5 m.
• Install 0.2 mm polyethylene moisture barrier
• Use hand-driven spikes for solid fixing to the slab
• Fix plywood sheets to the slab with hand driven 50mm x 6.5 mm spikes. A minimum of 20 spikes to be used per 2400mm x 1200mm sheet, equally spaced and with the outer spikes 75 mm to 100 mm from the sheet edge. It is recommended that sheets be staggered by 900 mm so that fixings do not line up from sheet to sheet when a brick pattern is used.
To minimise possible squeaks, use a cushion of polyurethane flooring adhesive between the two floors if staple fixing at close centres is being used. Apply continuous bead of adhesive at 90° to board length, midway between fixing points. In this case, staples may be spaced up to 450 mm apart.
