Has the problem appeared suddenly? If so, it’s likely that it’s due to a leak from a pipe or escape of water. The source could be from pipework in the floor or from the bath, shower, dishwasher, sink, WC or washing machine.

Check what you can but you may need the help of a plumber or a specialist water leak detection survey to locate the exact source. Once fixed, dry the area and make good. Biocraft can carry out water leak detection surveys and water leak restoration works.

Figure 1 – Dampness caused by a leaking pipe

If dampness is affecting outside walls or ceilings and is mainly black mould, it’s likely to be a condensation issue. Condensation is caused by warm, moist air coming into contact with cold surfaces. Solutions include reducing moisture in the air and improving your heating and ventilation systems or insulation.

Figure 2 – Condensation dampness on external wall

Is the problem high on the wall or ceiling or around doors, windows or the chimney? Does it appear as a stain and/or flaking/blistering paint or plaster? If so, it’s likely to be penetrating dampness.

You should check the roofing, guttering, pointing or brick work, the seals around doors and windows, drip grooves on windowsills. You may need a builder or handyman to carry out repairs to building detail. It’s a good idea to look outside when it is raining heavily to see if there are any problems with leaks or overflow guttering.

Figure 3 – Penetrating dampness

If there is dampness on the fireplace and chimney breast, it’s likely due to water ingress, lack of adequate ventilation to the chimney flue or combustion salt contamination.

Check the condition of the chimney, including pots and flashing. If the chimney or part of it isn’t used, it should have a ventilated covered pot and the fireplace should be ventilated to provide air flow up the chimney. Long-term water ingress can cause salt contamination which may need re-plastering after the source of the moisture has been removed and the masonry has had time to dry (6-18 months depending on the thickness of the wall).

Figure 4 – Damp penetration around chimney breast

If the problem is in the kitchen or bathroom and is at low level, it’s highly likely to be a leak or escape of water. This is the most common source of dampness in kitchens and bathrooms. Be aware the source of the moisture may be a little distance from the appearance of the damp, especially if the walls and floors are tiled.

The second most common type of damp in kitchens and bathrooms is condensation and mould. Improvements to heating and ventilation can help to eradicate this.

Figure 5 – Dampness caused to wall from leak in bathroom

If the problem is at low level, is long-term in nature and is very gradually getting worse over time, it may be rising dampness. It could however also be a bridged DPC, lack of subfloor ventilation or a blocked cavity. Rising damp is often misdiagnosed so it’s a good idea to get it looked at by a professional.

Figure 6 – Blocked cavity

If the problem is on a wall that’s below ground, such as a basement or semi-basement and there’s black mould, it’s likely a condensation issue due to lack of ventilation and/or heating. If there are no pipes, drains or appliances that could be causing the damp, it’s probably a failure or absence of waterproofing to the walls and floors and you will need specialist advice.

Figure 7 – Failed waterproofing causing dampness to basement floor

If you see black mould on the edges of the ceiling or in squares/rectangles, this can indicate missing loft insulation. Inadequate loft ventilation causes cold bridging which leads to condensation and mould. Refit loft insulation but make sure there is a 25-50mm ventilation gap above the insulation for ventilation.

Figure 8 – Severe condensation and mould caused by cold bridging and lack of ventilation

As with all damp issues, it’s essential to make sure the source is correctly diagnosed. Any remedial work should be carried out using compatible material for the type of building being worked on. Using sand and cement renders, plasters and pointing on a lime-built building for example, can lead to serious problems in the future. Biocraft can advise on dampness in traditionally built buildings and structures.

Figure 9 – Cement plinth and poor maintenance causing dampness to period property