Rising Damp Treatment & Damp Proof Course and Re-Plastering Repair

Rising damp is water from the ground that enters a structure by capillary action. Water that enters or effects a building through any other route can move about in various ways but is not rising damp. Only rising damp can be cured by the installation of a Chemical Injection dpc or Electro Osmosis damp proof course. 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 causing a dam affect, hence an increase in dampness.

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 a max of 2 metres above the finished floor level. The effects of Rising Damp is 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.

External walls are most likely to become affected, but internal walls also suffer if there is no effective damp-proof course established between the cavity. Rising damp often occurs when an existing damp-proof course has failed or become ‘bridged’.

Colne Valley Preservations are Registered BS6576 Approved Contractors with both Sovereign & Wykamol.

Electro Osmosis or Chemical Injection Damp Proof Courses are by far the most popular and efficient method of rising damp prevention. Installed in conjunction with the removal of old plaster and re-plastering in accordance with the BS6576 & B.W.P.D.A codes of practice it gives fully guaranteed results every time

Rising damp has been a relatively commonly encountered problem in some types of building however, it is often misdiagnosed. It is important that the investigations into dampness are undertaken by a trained and competent surveyor who can recognise and understand the problem. We would always recommend that the surveyor who undertakes investigations has been awarded the CSRT qualification which has relevance to the nature of the problem

Decayed skirting boards, crumbling or salt stained plaster, discoloration and staining, decayed timber floors and peeling paint and wallpaper are all common when walls are affected by rising damp. These defects are not always evident but when they are, a specialist inspection is always recommended.

Most types of masonry used in the walls of buildings will allow some water movement by capillary action; however, this is usually controlled by a physical barrier or damp proof course. If this physical barrier is absent, has broken down or is damaged then it is often possible to install a remedial damp proof course (DPC) to control water rising from the ground.

Water rising from the ground often introduces contaminating salts into the walls and plaster coats. This contamination will often result in a need for the plaster to be removed and replaced using specially formulated salt resistant plasters.

Overcoming Rising Damp

Rising damp usually affects the bottom of a wall at ground floor level. The most common defects that led to rising damp are a lack of an effective physical damp proof course in the wall or floor. This may be because the building was built without one, or the existing damp proof course has broken down, been damaged or has been covered over by wall finishes solid floors, soil or pathways. When a perfectly good physical damp proof course has been ‘bridged’ by earth from the garden or raised pathways, this can often be remedied by simply digging away all the soil or reducing the level allowing the physical damp course to work.
It is important that the investigations into dampness are undertaken by a trained and competent surveyor who can recognise and understand the problem.
Repairing Damp Caused Issues

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 of the injection of the DPC and the RE PLASTERING they are generally inseparable.
Our Surveyor will advise on exactly what remedial work is necessary.

Renovating Backing Plaster

Colne Valley Preservations use 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 than 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.

Renovating Finishing Plaster

Colne Valley Preservations also use a Renovating Finishing Plaster as the final coat over Renovating backing 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

Colne Valley Preservations use a salt inhibitor, 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.

Damp Proofing and Timber Treatment Recommendations

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