Rising Ground Moisture (Rising damp)


1. What causes rising damp?

Rising Dampness can develop within walls due to the lack of an effective damp proof course or the omission of damp proofing during earlier construction. In most cases, rising dampness is identified by moisture readings obtained around the base of the walls, however in more severe cases of prolonged dampness, visible damp patches may appear, along with hygroscopic salts on the wall surfaces.

2. How to spot if you need Rising Damp Treatment

Tell tale signs of rising damp include a “tide-mark” on the wall above skirting boards of up to 1 metre, peeling wallpaper and possibly white efflorescent salts which have been drawn out of the brickwork by the water. It is also important to note that rising damp only occurs on ground floor levels as it is moisture from the soil which is being drawn up the walls and thus causing the problem. If it is the case that your damp problem is on the first floor or above, it may be that you have a condensation problem.

3. How can I protect against rising damp?

The most common form of treatment for rising damp is to damp-proof your house or affected areas typically involves the installation of a chemical Damp Proofing Course (DPC). Typically, treatment involves removal of the skirting boards and wall plaster on the walls to be treated. The wall plaster is removed to approximately one metre or higher, depending on the salts within the masonry and several other factors. The damp proof course is installed into the walls by pattern drilling the masonry at the base of the wall and injecting a chemical Damp Proofing Cream or osmotic solution and then replacing any salt contaminated plasterwork. The installed damp proof course prevents moisture continuing to rise into the walls, however, due to the effects of ground salts, the walls will not dry out effectively, unless the existing wall plaster is removed and replaced using a salt retardant render.

4. What is the electro osmotic damp proofing method?

This type of treatment uses small electrical charges to move the moisture within the wall. The electrical charge repels the rising moisture molecules down the walls and harmlessly back into the ground. As long as this tiny positive charge is maintained, the protected walls remain dry and totally free of damp.

Professionals in this method then run small titanium wires around your house, with certain sections inserted into small holes drilled in your walls. The wires are connected to a computer system which monitors the condition of the wall at regular intervals and can provide the owner with a valuable history of the effectiveness of the damp proof course. The installation of this system is easily achieved and the costs of running it are similar to the cost of running your doorbell!

5.What Causes Penetrating Damp?

Penetrating damp is the ingress of water above the ground level, however it arises. Special care is necessary when investigating damp problems, particularly where the building has solid external walls, to differentiate between rising damp and penetrating damp. Penetrating damp may not just be the result of porous stone, brick or mortar, but may equally be attributable to faulty or blocked roof gutters, downpipes, flashings or flaunchings around chimneys and gable walls, faulty hip or valley flashings or tiles, missing slates or tiles, the absence of caulking or sealing around door and window openings and the absence of drip grooves below the window sills, etc.

6. How can I prevent penetrating damp?

  • Examine rain water goods (gutters, downpipes etc) along with flashing, rendering and window frames.
  • Check that downpipes are unobstructed and water can flow freely.
  • If the guttering is in need of repair think about replacing with new easy to fit plastic guttering.
  • Check the rendering for cracks, resealing any gaps that may exist around window frames.
  • Look beneath window sills and check the drip groove, used to shed rainwater so it does not hit the house wall. If this is blocked with moss or dirt clean it thoroughly.

7. Need a Survey?

If you require a survey to establish the condition of your walls for dampness issues then please ring “Joe” at our office on 0161 425 7595 to arrange a survey with one of our CSRT Qualified surveyors, who have been examined by the Institute of Wood Preserving & Damp Proofing.