Problem with damp walls in Hereford, Ledbury, Leominster, Ludlow, Malvern, Monmouth, Ross-on-Wye?

There are two main types of damp problem in buildings: rising damp and penetrating damp. Find out about them.

Rising damp is where there is a high moisture content at the base of the wall, which steadily rises further up the wall. Rarely over one metre above ground level.

It shows as…

• Damaged internal decoration – damp, discoloured tidemarks on wallpaper or painted surfaces.
• Damaged plaster work – blistering, salting and disintegration.
• Rotting skirting boards and/or floor timbers – wet rot decay.
• Localised dampness – dampness on lower section of walls, but may go much higher in extreme cases.
• Salt marks on outside brickwork.

There are many causes, but the most common are…

• No damp proof course or failure of an existing damp proof course.
• High ground outside ‘bridging’ (making a link to) above an existing damp proof course.
• Internal plastering ‘bridging’ an existing damp proof course.
• ‘Bridging’ of damp proof course due to build-up of rubble or rubbish inside a cavity wall.
• Residual dampness at the base of the wall following a previous damp problem.
• Leaking water pipes at the base of a wall.

And condensation is one of the most common causes of dampness in properties. Quite simply, condensation is water deposited on a surface from warm, moist air coming into contact with a cold surface. Usually more of a problem during the colder winter months.

Cold air enters a building, the air is warmed for comfort, the warm air takes up and holds moisture, this warm moist air comes into contact with cold surfaces and condensation occurs when excess water is released. Very often the first indication of condensation is black spot mould growth in the worst affected areas.

Condensation can also be seen as misting of windows leading to water droplets and even puddles of water on window sills. Other areas typically affected by condensation are cold external walls or pipe work, where there is poor air circulation, behind furniture, or in built-in cupboards.

Penetrating damp is water moving through walls from the outside of the building.

It shows as…

• Damaged internal décor – damp, discoloured tidemarks in line with the external ground level.
• Damaged plasterwork – blistering, salting and disintegration.
• Rotting skirting boards, floor timbers – wet rot decay.
• Degradation of brick work.
• Localised dampness – random damp patches at high and low level that do not dry out.
• Mould growth with a musty smell, spoilt decoration.

The most common causes of penetrating damp are…

• Building problems to old or faulty construction – defective roof coverings, cracked brickwork, badly fitting windows or door frames, guttering or downpipes not working properly.
• Lateral penetrating damp – caused when the ground outside, abutting the wall is above internal floor level.

You need tanking if the outside ground level is higher than the internal floor. Or where there’s old 9” brick walls, or old stone walls.

Treatment here needs to stop the water coming through the wall itself, rather than up from the ground (that’s the difference between rising and penetrating damp). You must appreciate this all takes several days, or part-days.

This is for above-ground damp only. There isn’t much cost advantage over traditional methods, but it is much quicker and les messy. Sovereign, our damp-proofing supplier, have a membrane product called ‘CDM3 LATH’.

Essentially, it’s like a wide-space bubble wrap, but much more substantial. First the damp wall may or may not need some initial treatment. Then the membrane is fixed to the damp wall with special plugs, with the bubble part facing the wall surface. The means there is an air-gap created. Ventilation grills or space, top and bottom, creates an airflow through this gap, and this stops the build-up of condensation.

Plasterboard panels can easily be fixed to the membrane, and the room is ready for normal decoration. Less treatment steps involved. And importantly, like with other Sovereign treatments, the work is guaranteed.

If the damp problem is less severe and the external and internal walls are in respectable condition, then you have the option of simple wall injections. This involves drilling a series of holes in a horizontal line, and injecting damp-proofing cream.

It may be possible to do this from the outside, which minimises disruption. But if it has to be inside, then skirting boards will probably have to be removed.

This treatment can be done on one visit which keeps the cost down, but there is a risk of salt marks appearing as the walls dry out over time. I will advise you, but you should be aware of this.

Robert Young,
63 Bulmer Avenue, Hereford HR1 1EJ.
t: 01432 355614
m: 07986 432634
[email protected]

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