Damp proofing - Four signs you have damp in your house

By Katie Anderson on November 17th, 2010

Damp ProofingCavity wall insulation and damp are usually referred to together, especially on online forums, but although insulation and damp proofing can be linked, having cavity wall insulation does not cause damp. In fact it can make an existing damp issue more apparent.

By installing cavity wall insulation you are not putting up a barrier to prevent water getting to the inside wall of your house – that’s what the outer wall does. Any moisture will move down the layer of insulation due to gravity and once it descends it can spread out and act as a channel between the outside and the inside wall.

Damp issues are caused by the condition of your outer wall so any issues with brickwork, brick pointing and leaking gutters should be resolved before having cavity wall insulation installed. Damp proofing is a measure that acts to prevent rising damp in a property by making sure moisture is unable to pass through the walls into the interior of the home.

Signs and causes of rising damp

The majority of damp problems in the home are caused by poor ventilation and the issues can be categorised in several ways.

  • Rising damp
  • Condensation
  • Penetrating damp

Condensation is the biggest culprit, along with rain penetration and rising damp. There are common signs which can indicate damp problems. These include:

  • Steamed up windows
  • Damp patches
  • Wallpaper peeling
  • Black spotty mildew
These are some of the most common warning signs. However, rising damp issues are harder to detect because the warning signs are not necessarily obvious. This is because it’s all happening below floor level. It’s only when you start to notice damp creeping up the walls that rising damp becomes obvious. Keep an eye out for patches of damp above skirting boards and damp smells.
Rising damp isn’t pleasant. It’s important not to leave it untreated, otherwise it could cause a lot of damage to structures, particularly timber decay.

A damp proofing course will fight off rising damp

There are instances where a property’s existing damp proofing course ceases to do the job effectively. And in some older buildings there may not be one at all. A damp proofing course is designed to offer resistance to moisture in the ground, so by injecting a chemical damp proofing course – usually a low odour water-based silicone “cream” – into the external walls it will act as a barrier against rising damp.

After holes have been drilled into the external/internal brick walls – to a predetermined depth and correct spacing between the holes – the water-based silicone cream is injected into the walls. Once a damp proofing course has been inserted, re-plastering tends to be necessary, and then redecorating. Although it’s worth noting that wallpaper cannot be applied until the walls are completely dry, which could take up to a year.

Damp proofing your property will only help prevent further moisture from rising from the ground. So if there are other sources of damp which are attributing to the problems they need to be addressed accordingly.


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