Damp On Walls

Penetrating Damp Is Common In Houses By The Sea

What Causes Penetrating Damp?

The causes of penetrating damp are related with the somewhat faulty building work or the fault in the plumbing work which has allowed water to enter into the structure. Properties near coastal areas or areas facing the sea can suffer from penetrating damp problems.

This penetrating damp results in serious deteriorating affects to the internal finishing like

• damp staining
• salting
• blown plaster
• peeling of the finishes in the internal areas

In addition, penetrating damp usually causes a visible watermark  on the internal wall which grows if the water continues to enter thus penetrating damp walls. Penetrating damp is caused by the porous nature of the building which permits external moisture to enter through the external walls which ultimately affects the internal surfaces. The defects in the construction of the building which are the root cause of penetrating damp include defective roof coverings/lead flashings, damaged mortar joints etc. Even when these defects can be cured, the affects of residual moisture within the building can continue to create problems for months and sometimes years. This is so because a damp wall will take one month for each inch of the wall thickness to dry out after the source of the penetrating damp is removed. Many older buildings have very very thick external walls and thus the affects of penetrating damp will continue over a longer period of time if nothing protective is done.
When the moisture from the wall evaporates, the chloride, nitrate and sulphate salts that are present in the wall manifest themselves in the the internal plastered surface and become “hydroscopic”. By saying hydroscopic it simply means that these chemicals present in the internal plastered walls attract the atmospheric moisture and become damp. And this happens particularly when the atmospheric levels of moisture are high. This is the reason why most of the cases of damp walls are experienced in winters and they continue to be present even after the source has been eliminated. It has been noticed that it is the single brick walls that are particularly open to the moisture from the atmosphere penetrating and during heavy rainfall the dampness worsens. It only takes about 45 minutes for an average brick to saturate and absorb the water. Needless to say that the bricks remain damp all the time, even if they appear and feel dry to touch. So, if you do have a single brick wall in habitable area, damp proofing is a must.

Analyzing the root cause of the penetrating damp is crucial, and if it can be fixed or expunged completely then you are well on the way. As important however is to determine the effect of residual dampness to close out the issue.

DIY Techniques For Treating Penetrating Damp

There are several DIY techniques that can be used on penetrating damp. First off, perform an audit of the affected site. Focus on areas that carry water or can leak, guttering, around windows and building piping. Water leaking from one of these will lead to penetrating damp. Cracks will lead to water getting in. Blocked drains are also a common source of penetrating damp. Clearing the obstruction will clear up the problem. Bad workmanship on roofs or  damage to the building structure can also be a catalyst for penetrating damp.

Damp Proof Membranes – A Permanent Solution
Damp Proof Membranes offer a quick, permanent solution and whether the penetrative damp is ongoing or due to residual moisture, the recommended Damp Proof Membrane would have a stud profile as this would stop penetrating damp and once installed the membranes provide a permanent separation barrier between the damp walls and internal finishes meaning a dry internal surface and protection are maintained at all times. This in turn creates ‘damp pressure equalisation’ which means that as differing internal and external air pressures equalise across the wall they effectively squeeze moisture which is in the air gap between the wall and membrane out of the structure. The studs also act as stilts holding areas of the membrane away from the surfaces to which they are applied and this maintains an air gap into which moisture and moisture vapour can evaporate and move unhindered. In addition it is completely impervious to the hygroscopic salts which are a bi-product of the penetrating damp and associated residual moisture. Damp Proof Membranes would be my recommended solution to cure penetrating damp and this also in turn creates ‘damp pressure equalisation’ which means that as differing internal and external air pressures equalise across the wall they effectively squeeze moisture which is in the air gap between the wall and membrane out of the structure.

Condensation Damp generally is a bi-product of the way we live and can effect damp walls, and damp cellars. Various things which we do on a regular basis exacerbate the levels of atmospheric moisture in our homes and buildings and this has a direct bearing on the levels of condensation damp. Cooking, bathing and showering increase moisture levels in the atmosphere with the average person expelling up to 5 pints of moisture in a night while sleeping!

Possible causes include:

• Lack of natural ventilation
• When there is a constant change in air temperature in a room
• When wall surfaces are damp and cold
• When radiators have been used excessively to dry clothes

Basically, air molecules are larger when they are warm and so they can hold more atmospheric moisture. When the air cools the molecules reduce in size and so are unable to hold the same amount of moisture, and therefore deposit the excess moisture on the surrounding surfaces. Visually this can appear as actual moisture and wet to the touch, or as black spot penicillium mould. Both can have detrimental affects to the internal finishes and the spores of the mould can manifest themselves permanently in the wall plaster.

Condensation damp can also be a health hazard especially to those who already have respiratory health problems.

Managing Condensation Damp

For below ground damp problems, a full damp tanking system should be applied to the damp cellar. When dealing with above ground condensation damp it is important to provide increased and regular levels of ventilation to facilitate regular air changes within a room. If this can be achieved naturally then some form of mechanical ventilation or climate control should be introduced.
In turn some attention must be given to the surfaces where the condensation is occurring particularly if damp mould has been present. Many people have realized that by using standard cleaning products or bleach it could be a futile exercise trying to eliminate penicillium mould as it keeps returning. If the spores of the mould have manifested themselves then the only option might be to remove the wall plaster or apply an impermeable damp proof membrane over the affected area.

Damp Proof Membranes – Application

Damp Proof Membranes could be applied to damp walls affected by condensation damp, staining and mould and penetrating damp. The recommended High Density Polypropylene and Polyethylene damp proof membranes would be moulded into a stud formation creating an air gap behind the system. The impervious nature of the damp proof membrane coupled with the ‘egg box’ stud profile means that while the membrane has been applied to the surface of the wall, mould spores caused due to condensation damp can no longer affect new finishes which would be applied to the Damp Proof Membrane. Similarly, any dampness in the structure would be prevented from affecting the wall finishes. A DIY damp expert or a professional damp specialist can apply the membrane.

The air gap provided by the studs of the membrane is a natural insulator and it means that when applied the membrane serves to gently warm up the wall’s surface and the thermal qualities could help in reducing the levels of condensation damp. The damp plaster could then dry out behind the membrane, thus permanently treating the damp.

Damp Proof Membrane Systems can be applied following the removal of contaminated wall finishes, or simply directly over the top of them

A contractor who has been frequently using Damp Proof Membranes said “We don’t mess about any more. Whenever we have a wall affected due to condensation damp and damp mould first of all we install better levels of ventillation – naturally or mechanically – and then we apply a Damp Proof Membrane to the walls and dab fix an insulated plasterboard. That way we get a nice dry and warm wall surface which considerably reduces the chances of condensation damp re-occuring”

Thus in my expert opinion, there are a number of do-it-yourself solutions for condensation damp, but if these don’t work, the installation of damp proof membranes to the damp walls would be the best permanent solution.