Rising Damp & Re-Plastering

Evidence of Rising Damp is easy to notice. It is represented by damp areas on walls often indicated by a band or tidemark visible up to 1metre above finished floor level, peeling wallpaper, mould growth and white fluffy efflorescent salts. Hygroscopic salts in the wall and plaster confirm that rising damp exists or has previously existed.
 It is caused by a capillary action of dampness rising from the ground up the wall through porous materials such as brickwork. Water drawn from the soil usually contains a low concentration of soluble salts. When evaporation occurs these salts crystallise out blocking pores in the brick, thus reducing evaporation, hence an increase in dampness.
External walls are most likely to become affected, but internal walls also suffer if there is no effective damp-proof course established. Rising damp often occurs when an existing damp-proof course has failed or become ‘bridged’.           

Colne Valley Plasterers are Registered BS6576 Approved Contractors with Sovereign.

Sovereign Injection Damp Proof Courses are by far the most popular method of rising damp prevention. Installed in conjunction with the removal of old plaster and re-plastering in accordance with the Sovereign Re-plastering Specification, gives fully guaranteed results every time.

Replastering
In order to complete an effective damp-proofing system it is extremely important that the new plasterwork which replaces the salt contaminated material resists the passage of residual moisture and contaminant salts from passing from the underlying substrate through to the new decorative surface. This function is extremely important because the underlying wall can take many months to dry down following damp-proofing.

Finally it is important to understand that damp proofing is a system – (1) the injection of the DPC and (2) the re-plastering: they are generally inseparable. Our Surveyor will advise on exactly what remedial work is necessary.

Renderlite Renovating Plaster
Colne Valley Plasterers use Renderlite Renovating Plaster which is breathable, but will not allow the passage of salts through to the surface. It also has a U value much higher then either sand/cement renders or gypsum based plasters. Particularly useful in areas where condensation may be a problem, such as cold external walls, or after tanking basements.

Renderlite Finishing Plaster
We also use Renderlite Finishing Plaster as the final coat over Sovereign Renderlite Renovating Plaster. When cured it forms a hard wall finish plaster that allows the walls to breathe. It has excellent adhesion and impact resistance and resists the passage of salts.

Rendermix
Alternativley we use a waterproofing additive for incorporation into the backing render coat after installation of a damp proof course. Used in sand:cement renders, it also provides workability so that further admixtures are not required. Used as recommended ensures that hygroscopic salts are prevented from moving to the surface plaster and exhibiting secondary dampness.

Don’t take the risk-always use a PCA registered contractor and ask for a CSRT qualified remedial surveyor.