Have a question? Read our frequently ask question section for useful answers to the most common questions.
Q1. I have blistering paintwork on the inside of my walls. What causes this?
A1. This could be due to either bad preparation of the surface prior to painting or possibly the signs of Damp.
Q2. In addition to the blistering of the paintwork there is a white, fluffy substance on the walls. What is this?
A2. This is efflorescent salts, most probably sulphates. They are brought to the surface during the process of evaporation. Have your walls checked for the presence of Damp.
Q3. I have damp patches in my carpet in the middle of our ground floor lounge. What could cause this?
A3. Depending on the age of the house, this could be due to either the failure or absence of a damp proof course (dpc) beneath the floor slab or the beginning of the break-up of an old malthoid dpc used prior to the introduction of modern plastic dpc sheeting. This requires professional treatment and you should contact a damp specialist.
Q4. I have damp patches appearing on the inner face of my external walls at a height of about 2m from the floor. What causes this?
A4. Once again this could be due to a number of reasons. First check the height of ground outside your walls. If this is above the height of your floor it could possibly be Rising Damp; if you have flower boxes on the outside it could be Lateral Damp due to a failure of waterproofing; if close to a window it could be due to leaking joints between the window frame or sill; it could also be due to descending damp from a leaking roof or possibly even Penetrating Damp through porous bricks or faulty mortar.
Q5. I have a basement/cellar and there is water appearing on the floor after heavy rains. What should I do?
A5. The waterproofing on the external face of your walls has obviously failed. Since we cannot now get access to this side of the wall we will have to treat the inner face of the walls with a cementitious slurry or other suitable waterproofing material to stop water ingress. In extreme cases it may be necessary to line the walls and floor with a drainage membrane and channel the water to a sump from which the water can be evacuated by means of a self-actuating pump.
Q6. I have efflorescent salts and damp appearing on my walls and ceiling beneath an upstairs balcony. What causes this?
A6. Either the balcony has not been waterproofed prior to tiling etc or the waterproofing has failed or did not properly cover the joints with outlets and side walls. A further problem could be a failure to adequately waterproof parapet walls. Have the balcony checked by an approved applicator.
Q7. I had my walls treated for damp a year ago but blistering and efflorescent salts have now appeared in the wall above the area that was treated.
A7. Damp can rise in walls to a maximum height of 1.2m above ground level. Where treatment fails to stop water ingress and the walls have simply been treated with a slurry but not to the full height of 1.2m, damp will continue to rise in the walls and damage any areas in between.
Q8. What causes the damage in my walls?
A8. All building materials contain a certain amount of moisture and natural salts. Only when excessive quantities of both are present do problems normally occur. Usually this comes from a failure or absence of dampproofing material which allows moisture and salts from the ground to enter the brickwork of our properties. As evaporation takes place, the salts carried in the water are drawn to the surface where they accumulate and start attacking our plaster and brickwork. Some of these salts are hygrophobic i.e they attract moisture from the air. If we fail to remove them completely they will continue to attract more salts to the surface as the moisture evaporates and the problems will persist.
Q9. Why do the south-facing walls on my property always appear damp and covered in dirt during the rainy season?
A9. South-facing walls hardly ever see the sun. During the rainy season face brick walls become saturated with rain and seldom dry out for weeks at a time. This provides a wonderful breeding ground for moss and other fungal growths. It is further exacerbated on the Highveld by winter frosts which often damage poorly mixed mortar. Moisture in the mortar turns to ice which in turn expands in the pores of the mortar causing the mortar to break down. Over time, holes develop in the mortar which allow moisture ingress and which in turn damages the plaster on the inner surface of the walls. Treatment with a water repellent, after first repairing the mortar, will prevent any further moisture ingress. However, standard water repellents have to be renewed every 2-3 years due to Ultra Violet attack on the surface molecules. Storm Dry is a deep penetrating cream-based water repellent which is totally unaffected by UV, lasting in excess of 20 years.
Q10. The Rhinolite walls in my bathroom are badly blistered and covered in a white powdery substance. What causes this?
A10. Rhinolite is a gypsum-based product which attracts moisture (hygroscopic). As such it should never be used in places where excess moisture, often in the form of water vapour from steam, is present, unless coated in a non-breathable paint. It should also not be applied over new plaster until the latter has fully cured – usually after 6-7 weeks. Steam (water vapour) reacts with the gypsum to form efflorescent, powdery salts causing damage to the Rhinolite surface.
Q11. How do I know if I have rising damp in my property?
A11. More than 90% of all damp problems in modern properties is caused by the practice of fitting plaster on external walls all the way down to ground level without leaving a gap in the plaster at the height of the damp proof course (dpc). Simply cutting a joint in the plaster at this height will contain damp below this point and prevent it from affecting the interior and exterior wall surfaces above the level of the dpc. In some homes, developers fail to fit dpc sheeting beneath floor slabs and only fit it in the brickwork, believing the concrete slab to be impermeable and non-porous. Regrettably this is not the case and damp will rise in the slab and first manifest itself as damp patches in carpets or damaged wooden flooring or damaged plaster and skirtings on internal walls. This is a serious condition and one which requires the services of a competent and professional dampproofer to create a new damp proof course over the slab. Homes built in the 1960’s, and older, were often fitted with a malthoid dpc which over time becomes brittle and allows moisture ingress. Many old homes also had suspended wooden floors which are prone to damp especially if airbricks and voids beneath the floors are filled in. Both situations require a carefully thought out solution and the services of a dampproofing specialist should be sought. The presence of damp on internal walls is often the first indication of rising damp in older properties or those without a dpc beneath a floor slab. But this could also be due to a failure to adequately waterproof a shower or may even be due to a leaking pipe. If in doubt, always seek professional advice.