The effects of damp in houses and how to solve the problem

A wall with loose render due to penetrating damp

Does your house suffer from damp?

Are the inside walls frequently wet?

Are there any patches of black mould inside?

Do you and your family suffer from asthma or get colds frequently?

Do you spend a lot on heating your home?

Does your house smell damp and musty?

Then there is a real possibility that you may have a damp problem in your home. Believe me, NOW, not later, is the time to sort this out.

Part of the reason that people live in houses is to protect them from the weather, albeit either in hot and sunny weather (to keep cool), or damp and cold weather (to stay warm and dry).

It wouldn’t be much fun living outside all the time and not in a house, office or apartment, and if that applied to you, you would probably not be sat here reading this right now!

It is essential that a house or building is not only designed to withstand the effects of the weather, both in its original construction, and also for the long term.

Houses require ongoing maintenance, which can be costly and full of hassle.

Legislation against damp in houses

In some cases, solving a damp problem and ongoing maintenance to a house can be a legal requirement, for example, with listed buildings, buildings in a public area, or a conservation area.

You may have restrictive covenants on the house whereby if you become the owner of the house, you MUST by law, concentrate every year on exterior house painting and having the correct exterior wall finish or finishes on your home.

These restrictions are designed to preserve the unique character of a particular home row or street of houses, or the surrounding area.

Failure to adhere to things like that damp proofing cost you dearly! If a house is not maintained, regardless of the above applying, problems will appear which can sometimes cost a lot of money.

What type of problems do houses of a certain age have?

Houses are generally built to last, after all, they wouldn’t sell if they didn’t last a long time, but over time, the weather and climate can literally attack your house in various ways.

A corner with cracked render so bad it fell off!

Common problems that occur on house exteriors can be things such as loose, blown, cracked or hollow render, cracking tyrolean, loose and cracked pebble-dash, loose or missing pointing (mortar joints), spalled or defaced bricks or blocks, loose and hollow stucco and masonry wall problems and a range of other issues.

Your home is under constant attack and all these issues can cause damp and water ingress.

The effects of damp in houses.

Other problems can also occur that are more serious, such as subsidence, land settlement or movement of the house, where the actual ground the house is sited on, moves in some way.


An extreme example of weather eroded bricks

I don’t need to emphasise too much that this is a very serious issue and if you do not have adequate buildings and home insurance, this will either cost you a lot of money personally, or maybe even bankrupt you, so it is very important whenever buying a house, to a full and through survey done by a professional surveyor, and don’t scrimp on costs when it comes to do something like that.

Pay cheap, pay twice as the saying goes

The occurrence of subsidence or settlement can be for various reasons such as landslip or landslides, opening up of forgotten industrial remains such as mine shafts or old abandoned tunnels.

Be warned as depending on how old the house is, your survey and plans may not show anything like the above so if you know that the land you are buying your house on is not old industrial land, for example, so check with your local records office, the local library should be able to point you in the right direction.

How to stop damp.

Damp can get into houses in the most unusual ways.

One house that NPA refurbished a while ago, in Plymouth, Devon, had evidence of German bomb damage from the 2nd world war when the city was devastated by Hitler’s Luftwaffe in 1941.


Repair work to previously hidden WW2 bomb damage

When we surveyed the property, the front of the house was bowing outwards and would have over time collapsed if not attended to.

Once the pebbledash was removed, we found evidence that the front of the house had been quickly and hastily rebuilt after its front was blown in during a bombing raid, probably in around 1942.

Needless to say we are all friends with Germany now of course and its all in the past, but the NPA team love a challenge and we sorted all the problems out very quickly.

Watch for cracks caused by damp

Any movement or settlement in your house can usually be noticed by cracks appearing or windows or doors suddenly being hard to open.

Cracks in the walls may also be internal as well as external. You should seek the advice of a surveyor as a matter of urgency if you suspect any of the above is happening to your home.

There are many other typical problems that can occur with your home and you need to get them checked out as, if you don’t, they will get worse and eventually will cost you more!

Damp coming into the house from outside?

It is also worth noting that damp doesn’t always come from the outside, so its worth investigating thoroughly to ascertain the source of the damp before committing to having any work done. Sometimes damp in house can be caused by rotten or leaking windows, cracked or leaky internal pipes, or by excessive condensation.

If your home suffers from condensation there are a few easy things you can do to reduce condensation:

Steps to reduce condensation

  • 1) Make sure you open the bathroom window after have a shower or a hot bath.
  • 2) If you have a tumble dryer, make sure it is operated in a well ventilated room.
  • 3) Make sure your home is well ventilated and the air is refreshed in each room every day by opening windows for a while.
  • 4) Install extractor fans in the kitchen and/or the bathroom or wet room.
  • 5) Install trickle vents in windows.
  • 6) Buy or hire a dehumidifier.

If you are not sure whether your walls are damp or not, an electronic damp tester can be bought from most good DIY and hardware stores. The tool is not particularly expensive and consists of a hand held electronic device with 2 metal prongs which stick into the wall.

NOTE: Some of the less reputable damp proofing companies will do a DAMP SURVEY of your home, and while you are not looking, will moisten the 2 metal prongs before they stick it into the wall, so even if the wall is fine, it will indicate damp, when possibly there may not be a problem, so be warned!

The 2 main types of damp, rising and penetrating damp, are not good things to have happen to your house. If you plan on doing any interior decoration, any damp problems must be cured before you attempt any decorating inside.


There are some damp sealers available in DIY stores, but they are often ineffective and can lead to the damp simply finding a different area of the wall in which to come through. Damp usually must be cured from the outside rather than internally, although in severe case of damp ingress, treatment must be done externally AND internally, to eradicate the damp.

After the damp is cured, you may need to employ the use of a stain blocker to the walls inside, before you begin your decorating project.

The two types of damp

There are 2 main types of damp problems that occur in buildings, mainly penetrating damp and rising damp, both can lead to serious problems if not dealt with. As a rough guide, rising damp, literally rises, from the ground, up to a level of about 4 feet and never any higher.

This is partially to do with gravity, pressure from the weather and also the level of the water table, the natural level at which water sits in the ground.

(The water table is the level at which ground water pressure is equal to atmospheric pressure, and can vary according to local climatic conditions and also the time of year.)

Rising damp?

rising damp
No, not the popular 1970s sitcom with Leonard Rossiter, that was funny, rising damp, if you have it in your home, is far from funny.

If you have rising damp then this means that the DPC (damp proof course) has either failed, or doesn’t exist at all.

What is a DPC?

The DPC, or “damp proof course” is a layer, usually of bituminous plastic or felt, that is built into the lower part of the wall, often at a level roughly just underneath where your floorboards are, in the void in between the ground and the floor inside. If a DPC is not installed correctly, or for some reason, the ground is HIGHER than the DPC, it will not work, and will let damp into your house.

If your home is built on a solid concrete slab and you do not have a void in between the ground and the floor, your home may have what is called a DPM, or Damp Proof Membrane.

This is large a large waterproof layer, often thick plastic, which is laid onto the ground when the concrete slab is poured from the lorry. If the DPM does not go right to the edge of the outside wall, damp can rise upwards, as if no DPC were installed.

So if I have a problem with rising damp like this, what can I do?

The best thing is to have a damp proofing company or exterior wall coating company visit your home and install what is known as a chemical DPC or Injected Damp Proof Course.

The operative will arrive with a special pump, a drill, a long drill bit, and a quantity of DPC chemical compound. The best known brands that we are aware of are Dryzone, dampcheck, toughcourse, envirosafe, to name but a few.

Most seem to be made Polyoxoaluminium Stearate (POAS), often carried in organic solvents, or sometimes something similar to Silicone.

It is worth making sure the damp proofing company have a good track record in doing damp proofing in houses before you employ any damp proofing firm to do the work.

We also respect any trade marks with these products and offer no review or recommendation, the names being posted are just for information only. Thank you

What about if my home suffers from penetrating damp?

One of the main causes of penetrating damp is the occurrence of spalling brickwork, cracked exterior render or pebbledash, or the face of bricks blown and detached from the surface, allowing water to soak into brickwork or substrate.

This can form voids or small hollow places behind the exterior wall surface which then fill up with water. Excessive blown render can hold quite a bit of water and will also make your home feel very cold inside.

During the winter, this water freezes, which of course then expands, and increases the size of the void and allows for more water to get in your wall. In extreme cases, if the loose or hollow render is not dealt with and repaired, it can actually fall off!

More bad render on the house

I think the house need more than just a “lick of paint” Madam….

Penetrating damp can usually be distinguished from rising damp insofar as rising damp, as we learned above, will only rise up to 4 feet, but penetrating dampness can appear in any part of your home, from the ground floor, to the upstairs.

Can damp in my house cause health problems?

Yes it can, and some serious ones too.

If you or any of your household suffers from a respiratory illness such as asthma, damp in your will make it worse, or in serious cases, could actually cause asthma.

In 2007, a study was carried out in Finland which showed that not only do poor housing conditions contribute to the illness but there was a debate whether they (damp houses) cause asthma, or simply trigger attacks.

The Finnish researchers writing in the European Respiratory Journal said they had proved this after surveying the homes of more than 300 children.

They found that after surveying all aspects of the damp house, they found a distinct link between mould in homes and childhood asthma, although this was disputed by some as not being a direct link, but a strong causal factor, nevertheless a damp home will certainly not help an asthmatic person.

Black mould on the walls

When black mould appears on the walls, as it is an organic organism, like a plant or a weed, it therefore requires moisture present in the wall, in order for it to grow.

mould on a wall can be cured by never paint again

Mould propagates itself and spreads by releasing tiny spores into the atmosphere of your home. These are airborne and are breathed in by whoever is in the house. This is often worse for your heath than smoking, it could be suggested.

If you have black mould inside your house, you must buy an anti fungal treatment or damp wall treatment and get rid of it as soon as possible. After this, it is most important to locate the SOURCE of the damp and have it repaired to stop it happening again.

Exterior spray applied wall coatings will do this as not only are the repairs done to the house where damp exists such as hollow render, but resin based wall finishes also have damp proofing properties in-built and are a sure fire way to cure the damp.

Plus the outside of your home will look great too!

In summary, having damp in your house can severely affect your health, can raise heating bills, will damage clothes, soft furnishings and curtains, and can eventually cause damage to very fabric of your home.

Please contact us now to find out how we can repair your damp quickly and permanently.

Call us FREE on (0800) 970 4928


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