2.10 Check and Prepare XPS
Preparation based on new substrate installations.
Check should be made using a straight edge to ensure the wall is flat, plumb and true. Any irregularities should be taken out by straightening using a rasp.
XPS substrate must be rasped to provide keying for Render application.
The Render coating is not designed to straighten deviations which exceed the specified Rockcote Render System thickness.
Once the substrate is deemed ready for plaster then the main contractor can continue to fix the internal linings, this is so that the main contractor can minimise the chance of any damage to the external plaster cladding that may be caused from the fixing process of the internal linings.
If the substrate has been left exposed to UV / sunlight for more than two weeks, dust and dirt may build up on the surface, the surface may also discolour (yellow) you must remove all surface dust, oxidisation, and other contaminants to reveal fresh polystyrene. Use a rasp or a stiff broom to prepare the substrate.
Before application of Render, apply masking to all joinery, pipes, roofs and all areas likely to be marked by the Render. Use drop cloths and ground covers to keep the working areas clean.
For further information on Light Reflectance Values (LRV) refer to TradeSpec™ Document 1.6 – Light Reflectance Values