The first course of action when curing a damp problem is to establish where the water source is coming from and how it is gaining entry in to the walls.
We recommend that you check out the following areas:
Bridged damp-proof course
* It is not uncommon for the ground levels surrounding a property to slowly rise as garden debris and external finishes such as decking and driveways are added.
* Check the perimeter of the property and be sure that these surfaces do not carry water to a level higher than your Damp Proof Course (DPC), effectively rendering it useless.
* Cavity wall insulation is also capable of bridging the DPC, so check that this has been properly installed and does not pass below the level of the DPC.
Broken or blocked guttering
* Broken or blocked rainwater equipment such as guttering, drainpipes, roofing and flashing can be large contributors to damp.
* If rainwater isn’t conducted safely away to drainage points, it will leak uncontrollably onto walls unprotected by a waterproof layer.
Defective ground and surface drainage
* As they meet the external perimeter, surfaces going up to the walls of your property should be angled slightly upwards so that rainwater drains away from the building.
* If ground drainage is blocked, rain and waste water will not be able to drain away promptly, and the property is at risk of flooding.
* This is caused by humid air hitting a cool surface, so check that kitchens, bathrooms and boilers are well ventilated to carry this moisture rich air away.
* The area beneath suspended wooden flooring is highly susceptible to condensation, so check that there are sufficient airbricks (all sides of the property, every 180cm (5ft 11in)) and most importantly that they are not blocked by garden debris or cavity wall insulation.
Broken or perished damp-proof course (DPC)
* If there is dampness on the ground floor, beginning at ground level or below, this usually means that a faulty Damp Proof Course (DPC) may be implicated.
* This could prove quite difficult to establish by eye or without invasive investigations, so we recommend that this should be considered after all of the other sources have been eliminated.
* Also if the property has suffered from subsidence, the DPC may well have been ruptured.
* Leaks are most often at the joints between shower trays or bathtubs and the walls, so check that sealant and grouting is in tact and continuous.
* Also check pipework for leaks, particularly at joins, which may simply be rectified by a new joint or washer.
Masonry & chimneys
* Check brickwork, rendering, stone and plinths for damage that compromises the waterproof surface.
* If the damp is in walls above a fireplace (not necessarily in the same room as the fire, but the room above!), hygroscopic salts are likely to be drawing moisture into the masonry.