BEVELBACK WEATHERBOARD CAVITY SYSTEM
3.1.2 Hermpac Bevelback and Rebated Bevelback Cedar Weatherboard Installation
Hermpac Bevelback and Rebated Bevelback weatherboards must not be wet prior to installation. Prior to installation, the back, face and edges of the Hermpac Bevelback and Rebated Bevelback weatherboards must be sealed with an exterior grade oil-based penetrating stain. During installation, cut ends must be sealed with an exterior grade oil- based penetrating stain.
Before the weatherboards are installed, the corner detail must be prepared to suit the selected option, e.g. external box corner, external corner moulding etc. The necessary flashings must be installed before commencing weatherboard fixing and the cavity closure must be installed continuously around the bottom of the cavity.
The first course of weatherboards must be full length, i.e. 4.88 m and commence from an external corner. The first weatherboard must be installed level to assist with the installation of subsequent weatherboards. The weatherboards must overhang the bottom plate by a minimum of 50 mm.
Immediately prior to installing the weatherboards over the internal and external corner flashings, a continuous bead of sealant must be applied to the face of the flashing along the fixing line.
Hermpac bevelback weatherboards must be overlapped a minimum of 32 mm. Hermpac rebated bevelback weatherboards must be overlapped a minimum of 25 mm with an expansion gap of 2 mm at the overlap. The top of the weatherboard lap must be restrained using the Hermpac clinch nail at every cavity batten.
Hermpac Bevelback and Rebated Bevelback weatherboards must be pre-drilled with a hole slightly smaller than that of the nail. Fix each weatherboard with one nail per board at every cavity batten. Fixing must be carried out using silicon bronze or Grade 316 stainless steel ring shank Hermpac Crown Head, Rose Head or Flat Head nails. The nail shank must be minimum 3.15 mm diameter and the length must allow minimum 30 mm penetration of the wall frame. The fixing must be located 35-40 mm above the bottom of the weatherboard, be located no closer than 32 mm from the end of the board, and must finish flush onto the surface of the weatherboard, not into or below the surface.
Fix weatherboards in full lengths where possible. Where joints are unavoidable, scarf the weatherboard at 45° over a cavity batten and fix with one fixing through the overlapping board.
3.1.3 Boxed Corners, Cover Battens and Mouldings
External and internal corners must be finished in accordance with the installation detailing.
Published: September 2009