Purpose
Sheathing material is normally applied to prefabricated wall panels by the timber frame manufacturer. At factory level its purpose is to:
Stiffen prefabricated panels for handling purposes.
Provide support to the panel to resist lateral loads.
Enclose and support wall insulation as well as provide a solid base for the breather membrane to be attached to.
Reduce wind penetration.
Reduce risk of damage or distortion to the panels prior to fixing.
Material requirements
All sheathing material must comply with I.S EN300:2006 and should have an approved certificate to verify it is fit for use in timber frame construction. Plywood is a typical material used for sheathing but the following items should be considered when choosing a suitable material:
Durability and fitness for purpose
Moisture resistance
Lateral load resistance
Where panels can be affected by moisture levels on site, a gap should be considered at design stage to allow for expansion. Sheathing should be a minimum of 5mm from the edges of panels with the breather material suitably wrapped to provide edge protection.
To aid fire resistance, sheathing material is required to be installed on the cavity side of each party wall. The sheathing should cover the walls up to a distance of 600 mm from either end.
