Damp Walls
Damp walls are one of the mysteries of many uk homes.
Where does the water come from?
How do the walls get wet?
Why do the walls get wet?
For how long has the wall been getting wet?
Solid water as a source for damp walls
Liquid water as a source for damp walls
Water vapour as a source for damp walls
Should I waterproof my wall?
Should I expect my old house to be damp?
What harm can damp walls do to a building?
What harm can damp walls do to humans?
What else can cause damp walls?
Can I fix my damp walls myself?
Is there any preventative maintenance that can mitigate the risk of getting damp walls?
Where does the water come from?
Water can exist in three forms, Solid (Ice), Liquid (water), or Gas (water vapour).
These are the three potential sources of water to make your walls damp.
The first form of water, Ice, is not a common cause although can manifest itself as damp walls.
The second form, or often our first thought, water, is often assumed to be the culprit of damp walls, yet this is not always correct.
Thirdly there is water vapour, a more common source of water on building walls than you might think. As a vapour it is not always visible, and the source not always obvious.
How do the walls get wet?
Damp walls can be caused by water (as a solid, liquid, or a vapour) coming into contact with the wall. The water gets to the wall from the top, bottom, or side.
Rising damp is a talked about as a cause for damp walls, although this is not often the case in our experience.
Structures can absorb a lot of water before they show signs of water on the surface of the wall. This can be caused by a small amount of water flowing for a long period of time or a large amount of water flowing for a short amount of time. Either way the volume of water can be considerable and be in the form of ice, water, or water vapour
Why do the walls get wet?
Walls get wet because there is a source of water coming in contact with them. The skill comes in identifying what the source of water causing the damp is, and how to rectify it.
An old factory recently converted into damp walled flats used construction methods were far from sympathetic to the building, poor design and poor workmanship. Many walls were damp, but where was the water coming from?
This took all of a matter of minutes to diagnose. A very leaky flat roof less than 10 years old.
So why were so many walls damp?
The water from the roof was making its way into the building as a liquid, evaporating into the warmer internal air causing extremly high relative humidity inside. This very humid air was then meeting the cold walls both visible on the paint and on the origional brickwork behind the plasterboard. The cold surfaces and air surrounding them did not have enough heat energy to hold the water in the air. At this point the relative humidity at the cold surface went beyond 100% and some of the water vapour in the air condensed.
Because there was a leaky roof, this process continued for years until the majority of the fabric was saturated.
The solution to this problem of damp walls was relatively simple.
How long has the wall been getting wet?
An important consideration when diagnosing the source of damp walls is how long have the walls been getting damp for?
If the damp is significant and has happened in a short period of time we could conclude that the source of the water is of a high volume but only flowing for a short time. These instances are generally an easy find and a simple fix because you are looking for a lot of water.
Many damp walls are caused by a slower flow of water over a longer period of time. This could be caused by anything from a small hole in a water pipe to a leaky gutter, but don’t forget the possibility of water vapour.
Whatever the source of water, and the time it has been flowing, the first thing to do to cure a damp wall is eliminate the source of water.
Solid water as a source of water for damp walls
Could Ice be causing your damp walls?
Lets consider your kitchen wall being damp behind the units.
Is it possible that the fridge or freezer in your kitchen is creating condensation, or is thawing. This would let water make its way to the floor and across to the wall.
Being hidden behind kitchen units, this problem may not be visible, but over a number of months or years the wall behind the kitchen units becomes saturated, and only when you begin to investigate do you find the severity of the problem.
Guess what? It can be solved.
Do you have an outside tap? Did it freeze last winter?
Pipes will sometimes burst as a direct result of the expansion of the water in them as it freezes. These cases of a water source making a wall wet are generally easy to find. Those same freezing temperatures can cause contraction of the pipe, and as it warms it begins to expand. This can stress the pipe to a point of failure and could happen over decades before the pipe finally fails.
Pipe failures can be as small as a pin prick, allowing a tiny amount of water to escape unnoticed. The culumanative effect of this small leak may manifest its self as a damp wall many weeks, months, or even years later
Liquid water as a source for damp walls
Possibly the most obvious cause of damp walls is a source of liquid water.
Our modern day buildings have a lot of water piped around them. This may be the water main into your house, the hot and cold water to your kitchen or bathroom, the water for your central heating or even the water in your gutters.
These water systems are complex, can suffer extremes of temperatures, are made with many joints and are often hidden out of sight.
Water traveling around our buildings, should it escape from its pipe, can wet walls from the top, bottom or sides.
Water can also be on, or in the ground outside the building, dependant on the construction of the building and surrounding ground this water can find its way to your walls and make them damp
Water Vapour as a source for damp walls
Often overlooked as a source of water making walls damp is water vapour.
This risk has been increased with our modern lifestyle of many boiling pans, kettles for frequent hot drinks and steamy showers. All of these create a lot of water vapour. Another significant source of water vapour is our own breath.
But how does a boiling kettle, or our own breath make a wall damp?
One explanation for water vapour making a wall damp is that first the water vapour is suspended in the warm air inside a building. This warm air has the capacity to hold a relatively large amount of water (a bit like a cloud). When this warm moist air meets a cooler surface the water vapour condenses and turns from a gas to a liquid.
The amount of water vapour created by activities in a modern building is considerable, and a continuous cycle of producing water vapour in a warm building, that travels in the air to cold surfaces before condensing can result in creating damp walls.
This process is more likely to happen in the colder months, when the temperature difference between internal air, and cold internal surfaces is at its greatest
Should I waterproof my wall?
As we have discussed so far, damp walls are wet because of a source of water.
In most situations this water source is temporary and has occured either due to a failure, poor design, or poor workmanship.
There are circumstances where walls should be waterproofed although only with thorough investigation and a design proven to be the best solution for a specific scenario.
Products are on the market that claim to cure damp issues. If you follow the instructions for these products, they make clear to rectify the problem before applying the product. Why, if you have rectified the problem would you need to apply a product?
As with every action, there are consequences, some good, some bad. If the proven problem to the solution is a product, can the product cause future problems?
Potentially. Some waterproofing products appear invisible once applied, yet are providing a water resistant layer to an often porus product. In an instance like this it is important for it to be obvious to people working on the treated damp wall to know that it has an invisible treatment, to help accuratly fault find future damp issues. If these products cant be seen, we don’t know they have been applied.
Waterproofing products are often less vapour open than the substrate they are applied to. These subatrates (for example brick) are capable of getting wet and drying out during inclement weather by their proven design. The drying process can occur by evaporation from the surface of the brick until you apply a waterproof product that restricts this evaporation process. Thee products will make the substrate surface less vapour open and reduce it ability to dry.
Damp proofing products do have their place in keeping walls dry, but if these products were not in the origional design for the building, be sure to prove applying them will be a positive solution for the problem with no negative consequences either now or in the future.
Should I expect my old house to be damp?
Houses are designed and built by professionals when they are new, so we would like to think they will be able to keep the water out.
Over their life time buildings are cared for and repaired to ensure their longevity. This can result in a patchwork of repairs, often not drempt about by the origional designer, so can they cause problems?
Certainly. In recent decades we have seen a shift in available materials and methods of construction that are being applied to older properties built with different materials and methods. This combination of old and new can cause problems.
One of the biggest differences between old and new materials is how they can deal with water. A few examples are…
- Timber Fascia and soffit
- Wooden Windows
- Lime Mortar
- Hand made clay bricks
- Vapour open paint
- No Insulation
- UPVC Fascia and soffit
- UPVC Windows
- Cement Mortar
- Engineering bricks
- Waterproof paint
- Vapour closed insulation
It can be the case that an old property that was designed to get wet and dry out can be comprimised by using modern vapour shut materials. Sometimes these materials form a barrier that water wanting to escape can no longer cross. The result is the water stopping and gathering at the surface of the modern vapour shut material.
If your old house has had a modern refurbishment and is sufferin from damp problems, could the mix of old and new materials be the problem?
Long term damp issues can cause structural damage in buildings. If your old house is still standing the chances are that it has been dry for most of its life and your damp problem is recent and can be rectified
It is not only the change in building methods and materials that have changed but also our life styles. Some modern cause our buildings to be potentially more dry, like gas fired central heating, and some more damp like a steamy shower or boiling electric kettle. Wether wetter or dryer, the use of the building has changed slightly and there will be some consequences, but with thoughtful design and fitting of new products and systems you should not be getting damp walls.
The maintenance of old buildings can cause problems as discussed but also there is the problem of lack of maintenance.
Are your rainwater goods clean and free flowing? Are your outside ground levels as origionally designed? Do you allow your outside tap to freeze during winter? Does any of your plumbing wast pipe leak? Do you loose pressure or water from your central heating system?
In conclusion NO, you should not expect your old house to be damp. If it is there is likely to be a solution that will eliminate the problem.
What harm can damp do to a building?
Water, although critical for life can also be very destructive.
Water in a building can destroy it, but how?
Read more about why buildings fail here. https://ww3.rics.org/uk/en/modus/business-and-skills/surveying-stories/why-buildings-fail–damp-can-become-dangerous.html
Rising Damp
We’ve never seen rising damp so cant comment. You can learn more here https://www.heritageanddesign.co.uk/types-of-dampness/rising-damp/