rising-damp-on-walls

What Causes Rising Damp?

Rising damp is caused by the rising of groundwater through the capillary action. If your property does not have a damp proof course (DPC) in place, then the building is vulnerable to rising damp occurring.

This type of damp mainly occurs in older buildings pre the 1950s. As this is a problem that is been occurring for years, most modern housing has a DPC installed at the initial construction phase.

Accredited to

Nic Glover

Branch Manager and Waterproofing Design Specialist CSRT CSSW
North East

Technician inserting damp proof course into wall

The damp proof course can be up from plastic, slate and bitumen, this depends on what period the building was built. There is also the issue that DPC can be bridged which occurs, if there is a construction fault with the building, then the damp can travel past the DPC from the ground.

Examples of construction faults that can occur are:

  • The insulation material in the cavity used is the wrong type
  • There is debris in the cavity wall
  • The internal render or plaster is overlapping the DPC installed
  • Grounds around the building has been raised above the DPC.

What Problems Does Rising Damp Cause?

Rising water causes problems of decorative spoiling and especially rot in skirtings, floor joists, floorboards and wall plates where present. Significantly, ground water salts will be deposited within the masonry and the surfaces especially plasters and decorative finishes.

Most groundwater only contains very small quantities of salts at levels which are generally at an acceptable level.

Ground levels above ground level

However, as the water rises within the wall these salts are carried up into the wall and left behind as the water evaporates. Over, say, periods in excess of 50 years the continual water rise and evaporation cause these salts to build up to quite significant quantities.

And here is where a further problem with long term rising damp occurs. A proportion of the salts are hygroscopic. This means that they can absorb water from the air.

In some cases, these salts are concentrated to such levels that sufficient water is absorbed from the air to cause contaminated finishes to appear damp.

This will cause future problems in that if the rising damp is stopped, materials may still remain damp solely due to the hygroscopic nature of the contaminated material. Any decorative finish applied to such contaminated substrates would almost certainly spoil with time.

If rising damp starts to affect the timber structures of your building then one of the outcomes that can be caused is dry rot. Dry rot is a wood rotting fungi that can spread throughout your property causing damage to the structural integrity of the building.

What to do next?

If you have identified the causes of rising damp, then the next step is to contact a damp specialist who is qualified in treating damp and timber. If you do not get in touch with a qualified professional, then there is the possibility that you will have an issue of misdiagnosis of rising damp.

It is often the case that Timberwise fix problems left by surveyors who have misdiagnosed the problem as rising which is in fact is a penetrating damp and condensation issue. The source of the damp problem should always be thoroughly checked to ensure that there is no further damage to the property leading to more expensive costs.

Timberwise is a damp proofing company with over 50 years of experience in dealing with all types of damp problems. You can get in touch by contacting Timberwise by our online contact form or by calling 0800 288 8660.

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