03 Jan DAMP OR CONDENSATION PROBLEM

Many home owners become confused, when trying to establish if they have a damp or condensation problem, when noticing moisture in the main walls.  Although condensation, often has symptoms to damp, green mould on plastered walls, for instance, its causes are quite different, from those of rising or penetrating damp.
Damp occurs, when a fault in the building’s basic structure lets in water from the outside.  There are two basic types of damp:
Penetrating Dampness.  This occurs, if water is coming in through the walls or roof, (for example, under a loose roof tile, crack to the walls, or faulty rainwater gutter).  The remedy, is to repair the source of the water ingress and after drying out, this should be the end of the problem.
Rising Damp:  This occurs, if there is a problem with the damp proof course (d.p.c.), if one was installed when the property was built.  A d.p.c. is a barrier built into the floors and walls, to stop moisture rising through the house, from the ground.  The usual evidence of rising damp, is a ‘tide mark’ on the walls, that shows how high it has risen, (normally maximum height, one metre from the floor) and sometimes accompanied by a musty smell.  The remedy for rising damp, is a new chemical injected damp proof course, or a new floor membrane, carried out by specialist contractors, being an expensive, but essential repair.
Condensation:  This occurs, when the moisture in the air, becomes cooler and tiny water droplets appear on surfaces, for example, when your mirror mists over after you have had a bath.  It usually happens during cold weather and appears on cold surfaces and places, where there is little movement of air, for example, in corners of rooms, on or near windows, in or behind furniture.  If left untreated, mould will begin to grow.
Condensation, may be considerably reduced or eradicated, by producing less moisture and keeping your home well ventilated, by slightly opening windows and keeping doors shut, particularly when the room is in use.  Try to reduce the moisture content of the air in the first place, generated by occupying the property, such as by cooking, tumble drier, drying clothes on radiators.  Maintain a low background heat, especially in cold weather, even when there is no-one at home.  Turning the heating up and down, when you come in or out, causes condensation, when the air and surfaces cool down.  Introduce powered extractor fans, or possibly install a dehumidifier, all reducing moisture content in the air.  Do not block up air bricks, that permit air to circulate the room.
For more information visit www.rics.org/propertysurveys.