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Bedroom damp caused by poor air circulation

Left untreated, damp can be bad for both your health (the mould and spores can aggravate respiratory problems such as asthma) and the health of your property: If any form of damp is left unchecked it can cause a number of potentially serious issues, including damage to decorated surfaces, or timber decay and even wet rot, which can lead to structural deterioration, and may necessitate major repair costs. More »

Penetrating damp in brickwork can cause major wall instabilities

Whether it’s damp proofing walls to prevent penetrating damp, treating rising damp, or dealing with condensation problems, damp proofing costs needn’t be prohibitive, though selecting the appropriate treatment will depend on the results of the damp survey. More »

Deep wall damp can be almost hidden behind plastering and wall paper

Penetrating damp: Once the source of the water ingress has been identified and repaired, treatments such as silicone water repellents, bitumen coatings, or a waterproof membrane can be applied to guard against future damp problems. More »

Brickwork affected by damp can cause serious problems for your home

Rising damp: Specialist creams are injected into the brickwork to form a waterproof barrier at the base of the wall; this will prevent water rising and penetrating into the building. Once the brickwork has dried out, the interior walls are re-plastered with plaster containing a waterproof additive. More »


Damp Proof Course

Despite sounding like something a trainee plumber might enrol on, a damp proof course (or DPC) is a physical barrier built or inserted horizontally into the walls of a building to prevent water rising up from the ground through the structure by capillary action (or rising damp, as it’s commonly known). The failure – or lack – of a damp proof course can have serious repercussions for the integrity of a property, and consulting a professional at the first sign of any problem is vital if serious damage is to be avoided.

What is a damp proof course made of?

Since 1875, every house in the UK has been built with a damp proof course in place. In older properties, this might have been a layer of slate or lead, or alternatively non-porous stone may have been used to build the first few layers of masonry. In more modern properties, the damp course may be constructed with engineering bricks, though more usually a (cheaper) thick plastic strip is typically bedded into the mortar between two courses of bricks, at around six inches above ground level.

What’s the difference between a damp proof course and a damp proof membrane?

A damp proof membrane (or DPM) is a thick polythene sheet laid under the floor slab to keep out groundwater. Welding the damp course to the damp proof membrane completely seals the inside of the building from the damp ground beneath it, thus providing a barrier to protect against both rising and penetrating damp.

Why is a damp proof course important?

If there is no damp proof course, or the existing one has become faulty in some way (perhaps becoming porous over time), or been bridged by something like a raised driveway or garden, serious problems can occur due to either rising or penetrating damp. Internally, these can range from damp walls, spoiling of or damage to decoration (including discoloured or bubbling paintwork, stained or lifting wallpaper, and/or mould on walls) and softening plasterwork, usually to a height of around a metre. Externally, there may be a visible ‘tide-mark’ on the wall, accompanied by white deposits from salts that have been carried up as the water rises, then left behind when it evaporates. If these signs are present, remedial work must be undertaken at the earliest opportunity to prevent more serious problems developing, including rotting skirting, floorboards and joists.

How is a faulty damp proof course repaired?

Damp proofing is a specialist job. Therefore, a professional survey by a damp-proofing firm (including the use of a damp meter to ascertain the extent of the problem) is recommended. Subsequently, they’ll be able to advise on the most appropriate solution. As it is rarely practical to remove a course of stone to place (or replace) a physical damp proof course in a wall, typically drilling a series of holes to allow the pressure-injection of a special cream which permeates the brickwork to form a waterproof barrier is the most effective – and least disruptive – option.