Permaproof Waterproofer is an all-purpose waterproofer, mortar plasticiser and salt inhibitor specifically suited for use with sand/cement render mixes particularly 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 does so 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 and that the plasterer carrying out the work is made aware of the importance of the re-plastering being carried out to specification in conjunction with the insertion of the Chemical DPC.
Permaproof Waterproofer is designed to minimise the passage of liquid water through the pore structure of cementitious renders, thereby preventing 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.
An all purpose waterproofer, mortar plasticiser and salt inhibitor specifically suited for use with sand/cement render mixes particularly after the insertion of a chemical DPC.
Replastering Specification Following the insertion of a Damp Proof Course
It is important that the re-plastering specification is strictly adhered to and that the plasterer carrying out the work is made aware of the importance of the re-plastering being carried out to specification in conjunction with the insertion of the Chemical DPC.
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.
Mix 3 parts sand to 1 part of cement. Mix gauging water with 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.
This 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.
This should be a porous mix of multi finish or similar board finish.
General Notes of Importance
Plasters must not bridge the DPC line and must finish short of the floor. Do not render below the injection holes. This will prevent damp within solid floors transferring itself to the new soft setting coat.
Unstable masonry must be made good prior to rendering.
Angle beads etc can be ‘dabbed’ with the sand and cement mix to avoid salting. Gypsum plasters must not be used to bond these metal angles to corners.
Any timber skirting to be re-fixed should have all unpainted surfaces treated with three coats of wood preservative. All new timbers or timber fixings should be similarly treated.
Do not use lightweight gypsum premix backing or bonding plasters e.g. Carlite.
The insertion of a DPC only controls further vertical ingress of water ie rising damp. The walls above DPC level remain wet and need time to dry out. This drying out time is governed by the initial moisture content of the wall thickness. BRE Digest 163 gives a general rate of 1 months drying out time for every 25mm of wall thickness.
The first decorations following treatment should be regarded as temporary and the recommended decorations at this stage are as follows.
1. Delay for 2-6 weeks following re-plastering and allow good ventilation to aid drying.
2. Redecorate using a low cost trade matt emulsion (non vinyl). 3. Do not use wallpapers for at least 1 year. Vinyl wallpapers for at least 2 years.
4. Allow good ventilation around treated wall surfaces.
5. Where early decoration is desired consideration should be given to lining walls with a membrane system in accordance with BS 6576. See separate data sheet.
Health & Safety
Render Additive/ Waterproofer is innocuous in normal use. Eye splashes should however be washed with large quantities of water and medical attention then obtained. Do not swallow.
Where the re-plastering specification has not been carried out correctly experience has shown that a property can visually appear to be no drier than before DPC treatment. It is therefore important when re-plastering after treatment that a correct re-plastering specification is used to prevent contamination of the new surface by residual moisture and migration of contaminant salts in the structure. This function must be carried out strictly in accordance with the Permagard Re-plastering Specification.
FOR USE BY PROFESSIONAL OPERATORS ONLY
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