Hidden water- How to prevent, find and fight a damp?

Mould, damp and condensation can be a problem for your property. It is important to make sure you are taking the right steps to prevent these problems in your property by undertaking any necessary damp proofing work. With all of the different types of damp-proofing available, how do you know what type is best for your project? When should it be done and how? Is it permanent or needs periodical  treatment?

How to know if you need damp proofing?

Damp Proof Levels (DPL) is a standard measure of the moisture resistance. The DPL rating levels are expressed in millimetres, with Level 0 being no protection and Level 20 providing complete immunity from any form of moisture ingress. If you know from which materials your building was built, then they have guaranteed levels of DPL and years they should survive without becoming damped. 

Much depends on materials from which building is constructed. Some of them have inbuilt DPL while others should be covered with a membrane. Wood should be covered in special paint or lacquer while tiles do not need that kind of protection.

If you have any concerns such as damp patches on walls, condensation or mould in your property then it is worth considering whether there may be moisture present that is causing these problems. 

Which properties need damp proofing?

The following are the main types of property that should be considered for damp proofing:

– homes and buildings constructed on a timber or metal frame, often with external cladding (previously known as “cavity wall construction”) – including those built in solid bricks or faced concrete

-buildings with flat roofs

-old buildings with plumbing in questionable condition

-buildings in low parts of the terrain

-buildings near water or on the coast

-buildings with a history of flooding

-properties in areas of  soft ground

-properties with a history of subsidence, or with unstable soils

-buildings constructed without damp proofing in the past. 

How often do you need damp proofing?

Damp proof courses are designed to last for between 20 and 40 years so they will require maintenance during this time period. In some cases it may be even earlier, if the damp problem is severe.

Where does damp come from? 

Damp comes from water either through the ground, or by rainwater that has penetrated into your property. This water is soaking through the ground, or through any cracks in your property’s foundations.

Rainwater that has penetrated into the fabric of your building and is collecting on surfaces inside is a perfect source of damp. Buildings that struggle with damp generally have basements areas or ground floor areas that are affected.

How to discover dampness?

Damp can be visible on the first sight, such as a dark patch on the wall and usually looks wet. Paint can fade or peel where it’s been touched by moisture. TVs and other electrical appliances can malfunction because they’re being moistened from behind. You may also find green patches inside your TV cabinets. 

However, damp can be tricky and remain hidden from the naked eye, only detectable by specialists. It is often discovered only during renovation works, such as pulling up a lino or carpet, and can be found through the smell of damp. There are also some tell-tale signs that you need to look out for. They can be incredibly sophisticated signals that contradict massive problems in your building construction.

To detect hidden problems the best way is to hire an expert and make your building undergo damp surveys. This should be done before some serious construction works, such as tiling or plastering. Neglecting this might result in expensive construction works and time-consuming fixing. Moreover, new tiles can be destroyed by hidden damp in the floor.

How to prevent your building from getting damp?

There are various methods of preventing the occurrence of hidden damp. They are not only beneficial for your property, but also will make you more comfortable and less worried about safety issues.


This method of preventing dampness is the main one. It is very simple and at the same time effective. This method includes installation of gutters, downpipes or drain covers to prevent damp from getting into your property through roof guttering channels. The water is collected in pipes and flows into the nearest water-way.

Limestone dust

A limestone dust sheet could also offer an option for those who are afraid of dampness in their properties. Limestone dust is laid on the floor and left for a day. The sheet is then vacuumed off to create an insulating layer of limestone dust that prevents damp coming up through floors, walls and ceilings.

Water-proof membranes

They can be put on  top of existing walls, ceilings or floors to provide an extra layer of protection against dampness. They contain substances like  tar, bitumen or polyurethane that are waterproof and keep the damp from coming through.

Ceiling tiles with a high water vapour resistance rating

If you have an old ceiling tile in your property it may be worth having them replaced with ones which resist moisture better. This is because older ceilings can become more easily damaged by condensation, especially in bathrooms or kitchens where there are  often steamy conditions.

Water-proof paint 

It’s possible to buy paints that are water resistant and these can be used to coat the walls of your property if it has a damp problem. They do tend to cost more than other types of paint but they won’t show up any stains or dirt like ordinary ones might. They are not solving the problem of the damp, but will protect your property from some of the effects.

Drying systems

In the event of severe dampness, you should speak to an expert about installing a system which will keep your property dry. It is usually possible for them to do this without damaging any structures or decoration and they can also advise on how often it might need maintenance in future. However if there are other problems such as leaks from pipes coming through ceilings, they need to be fixed first since it is pointless to install a system without first stopping the source of damp.

The type of drying system you need will depend on what is causing your problem, and while they are expensive to install. They do last a long time so it could be cheaper in the long run instead of doing repairs every year.


Damp is a popular problem in buildings and there are various methods to prevent and fight it. The most important step is to discover that there is dampness in a building because it can cause a lot of damage and be hard to find.

Some buildings have a problem with damp because they are old, while others could have pipes that leak or rising groundwater levels. The first thing you should do is speak to an expert who will be able to determine the type of problem and suggest the best way to fight with dampness in your building.

Interesting Related Article: “What Are The Common Causes Of Water Damage?