Dealing with rising damp: From diagnosis to a damp-proof wall

Rising damp, also known as capillary moisture, is groundwater that is drawn up into the walls through the foundations and the pores of the brickwork. You can compare it to a sponge lying in a layer of water, as the bricks in your external wall and the mortar gradually absorb the groundwater.

This problem mainly occurs in older properties where the original damp-proof course at the base of the wall is missing, damaged or has worn out.

How do you recognise rising damp?

• Location: The damp problem Always start at the bottom of the wall, just above the skirting boards, and it will reach a maximum height of 1 to 1.20 metres on your interior walls.
• Symptoms: Skirting boards coming away, crumbling plaster, peeling paint or wallpaper coming loose.
• White salt rash or saltpetre: As the groundwater contains mineral salts, these salts are left behind on the interior wall once the water has evaporated. This forms a white, powdery deposit on your interior wall.

Note: Not every damp patch on the walls in your home is rising damp. There are simply a number of damp problems that you may notice on your interior walls.

• Penetrating moisture seeps through the façade from outside following heavy rainfall.
• Condensation moisture is, in turn, caused by a lack of ventilation.

An accurate diagnosis of damp prevents you from choosing the wrong one moisture solution uses to solve the damp problem.

The most efficient and sustainable moisture solution to rising damp can be treated wall injection. In doing so, we create an impermeable, water-repellent or hydrophobic barrier within the internal wall, preventing groundwater from rising any further.

Why professional wall injection works when treating rising damp

• Capillary block: The injection solution penetrates deep into the pores of the brickwork. This alters the properties of the bricks in your wall, making them impervious to damp and water.
• Controlled distribution: Under controlled pressure, the hydrophobic liquid is distributed evenly throughout the wall, leaving no weak or permeable areas through which moisture can penetrate.
• Permanent barrier: Once the injected gel has set, the wall is permanently impermeable to groundwater and therefore to moisture.

Rising damp Treating damp is more than just drilling a few holes and filling them with a hydrophobic gel. It requires a well-thought-out approach to ensure that the accumulated salts and the finish of your wall are also dealt with correctly.

1. Moisture diagnosis on site: One of our experts will measure the moisture content in your home, and specifically in the wall with the tell-tale damp patches at the bottom. They will also determine the exact thickness of the wall and check for the presence of harmful salts. The first step in treating rising damp is therefore your free expertise Apply via AquaConsult.
2. Preparation and trimming: Before drilling begins, our experts remove the plasterwork affected by damp and salts to a height of at least 50 centimetres above the highest visible damp line on your wall. This exposes the bare brickwork and prevents any residual salts from damaging the new finish at a later stage.
3. Drilling the injection holes: Just above the floor or just above ground level on an external wall, our experts drill a series of holes into the wall. They do this at intervals of 10 to 12 centimetres to ensure a seamless overlap. The drilling is carried out at a slight angle of 10° to 45°, depending on the type of brick, or horizontally into the joint. These injection holes are approximately 80% to 90% of the wall thickness deep, so that the rear of the wall is fully reached without drilling right through it.
4. Thoroughly removing dust from the drill holes: Using a brush and a vacuum cleaner or compressed air, all drill holes are thoroughly cleared of debris and dust. This is essential because any remaining dust acts like a sponge, preventing the injection material from spreading evenly throughout the wall.
5. Injecting the hydrophobic gel or liquid: Using specialised injection equipment, our experts inject a high-quality injection gel or siloxane fluid deep into the drill holes. In the case of solid bricks, the material is injected under controlled low pressure. In the case of hollow bricks or gel applications, we fill the holes completely. The agent then spreads through the pores and the mortar joint across the entire width of the wall and cures to form a permanent, rubber-like or silicate water-repellent barrier.
6. Sealing the drill holes: Once the water-repellent agent has been fully absorbed by the brickwork, the drill holes are filled with a special, quick-drying and non-shrinking mortar to reseal the wall structure.
7. Salt buffering and remediation plaster: As old salts, such as saltpetre, may remain in the wall, we apply a salt-blocking membrane or remediation plaster. This prevents salt residues from affecting the future finishing layer or plastering undermine.
8. Drying out the wall: After wall grouting stops the inflow of moisture immediately. The residual moisture stored in the wall must now evaporate. As a rule of thumb, allow one month’s drying time per centimetre of wall thickness.