Rentokil Property Care

Rising Damp

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How to Identify Rising Damp

Our Rising Damp guide provides everything you need to know on how to identify rising damp, understand what causes it, and the best treatment methods to repair affected walls.

If you can spot any of the signs we detail in our guide, then it could mean that your existing damp proof course (DPC) has failed and you will need to install a remedial DPC to fix the problem. For more specialist help and advice continue reading or get in touch with your local team today on 0800 0121 437 or book a damp survey online.

What is Rising Damp?

The term rising damp describes the process whereby groundwater is drawn upwards through the brickwork, mortar and masonry of a building through capillary action, often resulting in damp stains and damage to the ground floor walls. Despite its infamy, rising damp is a relatively rare problem in modern houses.

Most properties have a damp proof barrier installed into the floor section of the wall to prevent capillary action and subsequent rising damp. However, as we will see these barriers can fail over time.

What Causes Rising Damp?

To prevent rising damp properties have a slate or bitumen membrane barrier installed approximately 150mm (6in) above ground level in the ground floor section of the wall. This is called a Damp Proof Course or DPC for short.

Unfortunately, these DPCs can fail due to age, deterioration, or damage caused by factors like subsidence, and this is the leading cause of rising damp. Modifications to a building like an extension or conservatory that have been built without a damp proof course also increase the risk of dampness.

Alongside this, you may discover that your home is suffering from rising damp due to a bridged damp proof course. A new installation like a flowerbed or new driveway can raise the ground level and bridge the DPC. Essentially this means that your rising damp barrier has been skipped over and the groundwater now has direct access through to the porous building materials straight into your home again.

Damp-proof courses can also be bridged if debris in a cavity wall piles up above the height of the DPC. If you cannot identify any of the above but you still have damp problems, then it is more likely that you require another damp proofing service for penetrating damp or black mould and condensation treatment.

How to Identify the Signs of Rising Damp

Whether in new or old buildings, it can be difficult to identify rising damp because some of its symptoms are easily confused with those of other damp problems such as condensation or penetrating damp.

That said, you can look out for the following signs that are typical of a rising damp problem:

Signs of Rising Damp

The following five symptoms are the most typical signs of rising damp. If you think you may have identified one or more of these in your home then you may want to consider contacting our specialists to discuss the best way to proceed with getting rid of damp from your walls.

Rising damp tidemarks on wall

Tidemarks & Damp Patches on Walls

Perhaps the most typical sign of rising damp is evidence of a tide mark effect where dampness stains appear above the skirting boards on ground floor walls up to a potential height of 1 metre.

As you would expect, this would leave affected areas of the wall damp to the touch.

White Salt Deposits on Wall

Known as hygroscopic salts, this occurs because as the water is carried into the building through capillary action, it carries with it ground salts that remain deposited on the plaster walls once the moisture begins to evaporate. These often have the appearance of fluffy white deposits on the wall.

Damp Wallpaper and Flaky Plaster

The repeated presence of moisture in the wall will cause damp patches on walls to deteriorate to the point where wallpaper will begin to peel from the wall itself.

Another common symptom of rising damp is that the damp behind the wall will cause the plaster to eventually begin to bubble and flake from the wall.

Decaying Timber - Skirting Boards & Floorboards

If rising damp is allowed to go untreated then you may find that associated problems like wood rot begin to take place on any timber surfaces affected by the moisture over a long period of time.

A rising damp survey specialist will be able to diagnose if the damp has led to wet rot or dry rot problems.

Damp Musty Smell

Once a wall has been affected by rising damp then it means water and moisture from the ground has access to the internal walls of the property. Naturally, this will result in a wet and saturated wall that, given time, will create a damp atmosphere in the room and a musty smell will eventually develop.

The only way to eradicate this smell is to install a form of damp proofing that will prevent water from entering the home through capillary action.

How to Repair Rising Damp

To treat rising damp and ensure it does not come back, then you will need to install a remedial damp proof course into the base of the wall. There are several types of DPC’s, however, the most common and reliable is via damp proof injection into the mortar joint in the brickwork.

Holes are drilled into the ground floor and filled via an applicator gun with our unique water-repellent damp proofing cream solution that has been tested, verified and certified to prevent capillary action and rising damp from affecting treated walls.

Once the diffusion cream sets and dries out then you are free to replaster the wall safe in the knowledge that your rising damp problem has been solved. After the wall has been re-plastered then your new DPC will be invisible.

You can read more about our rising damp treatment process and our 30-year guarantee on our dedicated pages.

Rising Damp Treatment on Internal Walls

Many people wonder what will happen to their internal walls once a remedial damp proof course has been installed.

Quite simply, once our technicians have replastered the area then the installation will be invisible and you can redecorate safe in the knowledge that the damp stains and hygroscopic salts are a thing of the past.

Is Rising Damp a Myth?

There is a school of thought out there that suggests rising damp is a myth, this is simply not true. Water rising through porous stone and brick via capillary action has been observed for centuries and is easily replicated by putting common building materials into water.

The reason there is controversy around rising damp is due to the high number of tradespeople who lack the experience and qualifications and subsequently misdiagnose the issue as another type of damp problem.

When other problems like condensation or penetrating damp are treated as though they are rising damp it is inevitable that the treatment fails and the property suffers.

So, it goes without saying that where rising damp is the genuine cause of the damp problems in your property it requires a survey and treatment plan from qualified damp specialist professionals.

Can you Buy a House with Rising Damp

If you are interested in a property that has damp issues listed on the home report it is certainly something you should have surveyed. The qualified and experienced surveyors at Rentokil Property Care will be able to establish why the rising damp is occurring and the best form of treatment to stop it. 

Your Local Rising Damp Specialists

Providing all of our customers with the highest quality of service is our highest priority. This is why we ensure all our surveyors are Certificated Surveyors in Remedial Treatment (CSRT) and our technicians are trained to Property Care Association (PCA) standards.

Identifying rising damp requires more than the use of a simple moisture meter. Our team of experts will assess and correctly diagnose the extent of your rising damp problem for you. From this, we provide recommendations on how to treat the issue and solve the problem. You can contact our expert team at Rentokil Property Care today on 0800 0121 437 or click the button below to book a survey online.