How To Treat Penetrating Damp
Last Updated 28 August 2018
What is penetrating damp?
Penetrating damp is damp that has entered the property from the exterior or from a leaking pipe. If water is entering a wall, floor or ceiling at a faster rate than it can dry out or drain, then it will saturate with water which leads to deep, damaging damp.
This damp is more than just an eyesore; it can lead to mould and rot which can cause severe damage to the structure, sometimes to the point that it’s no longer safe to be inside.
Huge chunks of plaster can suddenly crumble off a wall or ceiling and, if damp spreads to the timbers, it can lead to wet rot or create the ideal habitat for wood boring beetles, both of which can damage timbers to the point they need to be entirely replaced.
The quicker you address a damp problem, the easier and less expensive it is to treat.
What causes penetrating damp?
A wide variety of exterior defects can allow moisture to infiltrate a building. Here are some of the most common causes that we encounter:
Cracks in the walls:
A large enough crack in an exterior wall can allow rainwater into a building. Cracks also have a nasty habit of growing: what starts as a thin, hairline crack can be widened by the freeze-thaw of water until it’s wide enough to let water flow freely into the walls. Cracks are often found around the edges of door or window frames which haven’t been properly sealed or have separated due to movement of the building.
Just because a building is crack-free now doesn’t mean it’s going to stay that way. Vibrations from nearby heavy vehicles or construction work can gradually cause cracks to form in walls, as can subsidence, where poor ground quality or foundations causes part of a building to sink into the earth, literally tearing the walls apart. Be aware of any new cracks that appear in walls or ceilings as they may indicate a more severe problem.
Leaking roof or chimneys:
Missing tiles, damaged rafters or inadequate drainage all give water a chance to seep into a building. This water often travels along the structure before pooling elsewhere, such as the edge of walls or around light fittings, so the site where the damp is visible isn’t always the same as the site of the leak.
Chimneys are also common problem areas for damp. The point where the roof meets the chimney breast is often poorly sealed, allowing water to seep along the side of the chimney breast and down into the attic, or the chimney pots may have no cowls on them or the cowls have been damaged, letting water pass straight down.
Decayed pointing:
Pointing (the cement or mortar used to full the joints of brickwork or masonry) which has deteriorated or of poor quality can allow rainwater to seep between the bricks, where it may find its way deep into the walls or create cracks by freezing and thawing. Our wet British weather means that all pointing needs to be eventually replaced, but a good pointing job should last decades or more.
If you can easily remove chunks of pointing with your fingers or crumble it away with a butter knife, then your brickwork is due a repointing, otherwise the walls and the rest of the structure is vulnerable to damp problems. Pointing is also another cause of chimney leaks.
Blocked or cracked gutters or plumbing:
Pipes and gutters which move water through or away from the building can cause penetrating damp if they are blocked or cracked. Unblocking a gutter is as simple as removing the leaves or other debris causing the blockage, while cracked gutters are easily spotted and replaced.
Leaking plumbing is more difficult, as the exact source of the blockage or breakage may be buried deep in the walls, requiring invasive building work to find the source of the problem and replace the damaged pipes. Old copper hot water pipes are more vulnerable to breakage as the expansion and contraction can, over time, weaken the pipes or solder until they crack.
How to spot penetrating damp
Dark or discoloured patches on walls or ceilings are the most obvious sign that you have penetrating damp in your building. In severe cases, these patches may be wet to the touch or dripping. Other symptoms are cracked, peeling or bubbly-looking paint, crumbling plaster or mould – along with its distinctive smell.
How to treat penetrating damp
The first step is to find and eliminate the source of the damp, which could be any of the causes mentioned above. A thorough examination of the exterior of the building is carried out to find all current and potential points of water penetration.
Simply painting over damp or re-plastering walls is a temporary solution at best, and attempts to cover up damp won’t hide it from moisture meters when the time comes to sell the property.
Eliminating the source of damp ranges from quick and easy to time consuming and highly invasive depending on the cause.
Best case scenario: we pull some leaves out of a gutter or reseal a window. Worst case: we have to strip back walls to find leaking pipes or repoint the entire exterior. Either way, the Environ team is skilled in every trade required to get a building 100% leak-free.
Next is removing any materials that have been affected by the damp, which typically involves stripping back damp paint and plaster all the way down to the brickwork and leaving it to dry. In more severe cases where timbers have rotted, we may need to brace the building to provide extra support while the timbers are replaced.
Finally, we apply a special three-part render from Sovereign, a world-class supplier of damp proofing solutions. We’ll then provide you with a guarantee for all works completed.
If you have any questions about penetrating damp or want to book a free, no obligation survey and quote, call Environ or request your call back today.
