Render Additive Waterproofer
Permaproof Waterproofer is an all-purpose waterproofer, mortar plasticiser and salt inhibitor specifically suited for use with sand / cement render mixes. It is often used after the insertion of a chemical DPC and in other waterproofing applications.
It is common for walls that have suffered from rising damp to be contaminated with high levels of salts. After the insertion of a new damp proof course, the wall will start to dry out. As the wall dries, these salts may be deposited on or near the surface and give rise to efflorescence. If the salts are hygroscopic, damp patches may also develop when the ambient humidity is high. It is essential that the re-plastering specification is strictly adhered to. The plasterer carrying out the work needs to be made aware of the importance of the re-plastering being carried out to specification in conjunction with the insertion of the Chemical DPC.
This waterproof additive for render is designed to minimise the passage of liquid water through the pore structure of cementitious renders. This prevents the passage of salts to the surface in the drying out period.
Re-plastering should be carried out as long as possible after the insertion of a remedial damp-proof course. Ideally the new plaster should be applied to surface-dry walls, but in any case a drying period of at least 14 days should be allowed between installation and re-plastering wherever possible.
1 litre of concentrate is sufficient for approximately 7m² of render at 12mm thickness
Using Permaproof Waterproofer - Replastering Specification
After the Damp Proof Course is inserted:
Preparatory Work
1. Take down timber skirting, architraves, disconnect radiators etc.2. Remove old plaster back to brick or stone to a height not less than 1 metre high or 500mm above the highest level of visible damp or salt contaminated plaster.3. Rake all mortar joints to a depth of 12mm and prepare masonry to provide a good key.4. Remove any organic matter from the masonry and if appropriate fix any required future attachments into the masonry at this stage.
Mixing & Materials
1. Ordinary Portland Cement to BS12. Fresh and free flowing.2. Clean washed, sharp sand graded to BS882: 1983. Coarsest, sharpest plastering grade.3. Admixture – Render Additive mixed as specified.4. Clean water fit for drinking and free from any organic matter.
First CoatMix 3 parts sand to 1 part of cement. Mix gauging water with Permaproof Waterproofer Render Additive at 30-1 ratio as specified. Add minimum amount of gauging water to dry mix to ensure a dense coat. An approximation of not more than 8 litres per 50 kilos of dry mix should be used as a guide. Render the surface to give an overall thickness of between 10-15mm ensuring that the mix is compacted into the joints. Scratch to form a key when the cement obtains its first set. Do not over trowel.
Second CoatThis mix is as for the first coat applied to give an overall thickness for two coats of about 25mm. Apply this coat before the first coat has finally set in order to obtain satisfactory adhesion between the rendering coats. Scratch the surface to form a key. Do not over trowel.
Finish CoatThis should be a porous mix of multi finish or similar board finish.
Read our guide on how to re-render after installing a DPC.
