Damp Walls

Damp walls are encountered in buildings of all ages. The most common causes are rain penetration, condensation, and rising damp. Other causes can include leaking pipes and construction moisture (e.g where a new wall has recently been built and water in the mortar is still evaporating). In below ground situations (cellars & basements) moisture ingress from the ground is the most common cause of dampness.

The most appropriate method for dealing with damp walls will depend on the cause of dampness. It should be remembered that walls may be damp due a combination of causes - e.g. walls suffering from rising damp are sometimes affected by condensation as the rising damp causes the wall to cool, making it more susceptible to condensation. Correct diagnosis of the cause (or causes) of dampness is therefore vital before a decision is made on the best method of treatment.

Rain Penetration

Rain penetration through walls can occur for a multitude of reasons including cracks in masonry, faulty pointing, and defective seals around windows. In some cases the wall suffering from rain penetration is built from particularly porous materials. In these cases Stormdry Masonry Protection Cream can offer a solution.

Oldroyd Xp Plaster Membrane can also be used to cover up damp walls caused by rain penetration.

Our Stormdry Masonry Absorption Gauge is a useful tool for diagnosing routes of rain penetration through walls.

Rising Damp

Two products are available for the treatment of rising damp. The first and fastest option is Dryrod Damp-Proofing Rods. The patented 12 mm rods contain a strong water repellent material, which disperses into the mortar course after the rods have been introduced into the wall. The rods distribute the correct amount of active ingredients and are perfect for use in situations that need fast, targeted and high-strength treatments.

The second option is Dryzone Damp-Proofing Cream. Dryzone is injected into holes drilled along a mortar course. Once installed, it spreads along the mortar course before curing to form a damp-proof course. Dryzone’s optimised high-strength formulation results in a more effective damp-proof course than low-strength competitor products. Independent tests demonstrate that Dryzone even works in highly saturated walls (up to 95% saturation).

In most cases where walls are affected by rising damp, salt-contaminated plaster will need to be hacked off and replaced with either:

• The Dryzone Express System, with which rooms can be decorated again within 24 hours
• Dryzone damp-resistant plasters
• A sand:cement render containing diluted Renderguard Gold
• Oldroyd Xp Plaster Membrane covered with a suitable plaster (or plasterboard)

In some cases (e.g. period properties) it may be desirable to retain as much as the original plaster as possible. In many cases this is possible, but it will result in considerable delays before the wall can be redecorated. BS6576 states that:

Where the plaster appears to be in sound condition, the extent of plaster to be removed may be minimised by delaying any decision to replaster until the drying period is complete. In such cases the surveyor should offer clear advice on the risks arising of possible damage to decorations in the future.

Condensation

Walls can become damp when water vapour condenses on them. This form of dampness is known as condensation.

Condensation is caused by a combination of excess moisture being generated in a building (e.g. due to cooking and the drying of clothes) and cold internal surfaces. Although products are available to deal with the effects of condensation it is usually best to try and deal with the root causes - i.e.:

• Reduce moisture production (e.g. by drying clothes outside)
• Improve ventilation (to remove moisture-laden air)
• Improve surface temperatures of walls (e.g. using insulation such as the Ultrotherm Insulation System)

The Ultrotherm Insulation System and  Stormdry Masonry Protection Cream can have a role to play in reducing condensation by increasing the surface temperatures of affected walls. They can be particularly useful when dealing with “hard to treat” properties which cannot easily be insulated using traditional methods. Call our technical department for details.