Preparation of the Surface

1. Block or Brick Surfaces
No surface preparation is required although it would be advisable to apply scratch coat with a water sealer for chimney stacks to minimise water penetration. Check newly poured concrete surface for oils or release agents by spraying with water. A release agent can be detected if the water beads up or runs off wall.

2. Plywood or Other Rigid Wood Related Sheating
Cover the wall with a weather resistant barrier ( breather membrane). The building paper should be applied horizontally with the upper layer lapped over the lower layer not less than 100mm. Where vertical joints occur the paper should be lapped not less thab 150mm. Interior stud walls (wood framing) should have a metal lath installed. Exterior applications will require a galvanised metal lath. Apply a 10mm/12mm thick base of mortar over the metal lath and allow to set for 48hours.

3. Painted Sealed or Treated Block Brick Concrete or Other Masonary
The surface must be cleaned back to its origional surface by sandblasting, water blasting, acid etching or wire brushing
or
Have metal lath attached using corrosive resistant concrete nails with a scratch coat applied over the metal lath. For any uneven or rough surface, it is recommended to scratch coat to level the surface.

4. Chimney or Bay Windows at Lead Locations
It is recommended to fix a 50 X 35mm treated timber batten to build out the lead flush with the outer face of the stone to conceal the thickness of the stone.

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