Damp proofing your house

Damp proofing your house - how to go about it

A beautiful house will be all for naught because of damp. Dampness in a building can cause damages to it. Continuous moisture on walls and flooring can be the start of your house's affair with fungi! Any fungus infestation can rot the wood materials used in your house. Continuous dampness can also damage wallpapers, wall plaster and paint to loosen. Stains and mould are not unusual as they ruin the aesthetics and even structural stability of the wall. The mortar may collapse bringing the whole wall down an occurrence that could have a major effect on your house's structural stability. Worse, if the foundation footings themselves are continuously exposed to damp.

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A house that is continually damp poses a threat to the occupant's health too. Mould and damp can have an adverse effect on a person's respiratory system. As moulds are fungi, there is no telling what other treat they could bring to a person's health.

Two Kinds of Dampness

A damp is damp but there are two ways that dampness can seep in your home. The first one is intrusional dampness which could be further differentiated into penetration dampness or rising damp. Penetration dampness is the most common type of damp. Moisture from the outside can seep into the foundation, walls, and flooring through visible or invisible gaps in the structure. The other type of intrusional dampness is rising dampness which could be explained as ground water rising up a masonry wall through porous parts of the structure.

The second type of dampness is condensation. It is the moisture within the building itself caused by cooking, bathing, not enough heating and ventilation. This is not a serious "damp" problem as condensation can be remedied by putting a humidifier in the room, or improving the heating and ventilation of the room.

Causes of Penetrating damp and/or Rising damp

Rising damp and penetrating damp become problems when moisture has seeped into permeable parts of the structure and have started to dissolve salt from the materials such as calcium sulphate. The salt can leave a residue of powdery salt in the interiors and could also leave an unappealing water mark. The true problem occurs when the affected part of the house are the foundations. The usual cause of water pooling at the base of walls and foundations are incorrect and defective ground and surface drainage. The moisture could also be caused by defective and leaky plumbing. The dampness may be further be increased by condensation. Some other causes of penetrating and rising damp are:

  • Roofing defects that allow rain water to seep in the walls of the house
  • Defective brick or masonry construction
  • Clogged or blocked drainage pipes
  • No DPC or damp proof course
  • Driveways, walkways, lawn, flower beds, raised above damp proof course
  • Use of non-breathable cements and paints
  • Defective cavity wall tray


Damp Proofing

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The most obvious way to damp proof your house in from the onset. The house should be designed and built to satisfy the requirements of basic damp proofing. The slope of the site and the drainage pipes should conform. The materials and concrete used should have waterproofing additives or chemicals upon construction. Waterproofing is different from damp proofing. With foundation footings and walls footing including below grade constructions such as basement walls and flooring, waterproofing is the way to go. Using non-porous materials is a plus but in case you want to use timber for your home, make sure the wall footings and walls to which the timber will be applied is safe from rising damp.

In the UK, damp proof course (DPC) of about 150 mm are placed above ground to act as a blockade for water. It is usual to see DPC placed horizontally to stop water that could rise from the ground and then absorbed by the masonry above. The horizontal DPC is recommended to be placed at about 150 mm from the ground with a damp proof membrane. The DPC could also be placed vertically, between the structural wall and veneer of the building to stop the seepage of water from external elements most especially rain water. In many older homes, the use of non-porous materials were used in the first few layers of the wall. However, these non-porous stones are likely to become porous after some years. Treating these walls can be done by injecting chemicals into the walls thus making them obtain a degree of damp proofing. This option is best done by a professional. Another type of damp proofing is by using an Osmotic Electrical system. The idea is to insert anodes ((titanium wire) into the walls, plug into an electrical socket to serve as heat source within the wall itself. This is recommended for thick walls and should be installed by a professional.

What about damp proofing your basement floor? The best is of course, waterproofing the flooring during construction. Again the importance of waterproofing the foundations and basement cannot be more emphasized. A damp and moist basement walls and flooring are not conducive. If waterproofing has been done on the flooring but somehow moisture is still present, test if the moisture is by condensation or rising damp. As mentioned earlier, condensation is can easily be remedied. If the moisture is through rising damp, you can apply an epoxy floor coating to your basement flooring. The system is inexpensive and easy to do. Currently there are damp proofing injectables called DPC creams that claim easy application for any DIY-er.

The key in damp proofing your house is to have a qualified person inspect your house and find the cause of the damp. Once you have pin-pointed the source of your problem, then decide if you want to the damp proofing yourself or secure the services of a qualified person.

"Some food for thought and, whilst still leaving me with some uncertainties about the exact cause of my dampness problem, your suggestions are worth further investigation. Thanks. "

Trevor J Visick