Rentokil Property Care

Rising Damp

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Rising Damp Signs & Treatment

Our Rising Damp guide provides everything you need to know about rising damp, what causes it, how to spot the signs, and the best treatment methods to restore affected walls. 

Rising damp is the general term for water that is absorbed by the fabric of a building from the surrounding ground, often resulting in damage to the ground floor walls. If you think you have seen some of the signs of rising damp in your property then call the qualified team at Rentokil Property Care today on 0800 0121 437 or book a survey online.

What is Rising Damp?

The term “rising damp” describes the process whereby ground water is drawn upwards through the mortar and masonry of a building through capillary action. Porous building materials such as bricks and sandstone are the most likely to be affected.

All building materials have complex pore structures and the smaller the pores, the higher the water can rise. This moisture often brings groundwater salts and other contaminants with it, and these deteriorate building materials and decorative fixtures and fittings.

In most cases rising damp is a slow process and may be present in a building for several years before any signs of a problem appear. The speed at which the moisture rises up the walls will depend on several factors including:

  • The type of wall or floor construction
  • The nature of the ground
  • The environment inside and outside of the building

What Causes Rising Damp?

Despite its infamy, rising damp is a relatively rare problem, and will only occur if one or more of the following circumstances are present:

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

Unfortunately, these DPC’s can fail due to age, deterioration, or damage caused by factors like subsidence. Modifications to a building like an extension or conservatory that have been built without a damp proof course also increase the risk of rising damp.

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 condensation treatment.

How to Identify the Signs of Rising Damp

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:

Tidemarks Along the Lower Wall

Perhaps the most typical sign of rising damp is evidence of a tidemark effect where damp stains appear above the ground floor wall up to a potential height of 1 metre above the skirting board.

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

White Salt Deposits on the Lower 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, Peeling Wallpaper and Flaky Plaster

The repeated presence of moisture in the wall will cause damp patches on walls to deteriorate into the wallpaper beginning 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 e.g. Skirting Boards, Floor Boards & Joists

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.

Musty Smell

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.

Rising Damp Treatment

Treating rising damp can be a tricky task to take on independently due to the various potential causes and the accuracy with which the treatment must be applied to be effective. This is why we provide specialist rising damp solutions that are covered by a 30-year guarantee which can be passed on to future owners of the property for complete peace of mind.

The steps below cover what you can expect from rising damp treatment by Rentokil Property Care:

below we outline our rising damp treatment process step-by-step:

  • Rising damp survey - Using their extensive experience and expertise, a Rentokil surveyor will carry out a detailed survey to pin-point the most appropriate rising damp treatment for your property. This plan will include some combination of the treatment options below...

  • Install a remedial damp proof course - Dependant on the thickness of the walls, holes are drilled in the mortar/brick to a pre-determined depth and at the correct level and spacing. These holes are then injected with a low odour water based silicone damp proofing fluid (damp proof course) to reduce the movement of water through the capillaries.

  • Repair or replace a damp-proof membrane - Damp proof membranes can also be used in rising damp treatment. These membranes can be installed immediately after the injection or repair of a damp proof course and used as a key for any new plaster. The membrane will separate any new plaster from existing salts and other contaminants on walls.

  • Re-plastering - Once our team has completed treating your home for rising damp our technician will ensure any treated walls are re-plastered with a waterproof additive.

Treating Rising Damp on Internal Walls

Most property owners identify a rising damp problem when they spot damp patches on their internal walls. Before any treatment for rising damp on internal walls can start, technicians will need to lift skirting boards around the affected area and remove any plaster that has been contaminated by hygroscopic salts.

Once the area has been prepared out technicians can begin installing a remedial damp proof course via our DPC injection method.

How to Treat Rising Damp on External Walls

Rising damp problems caused by elevated ground levels can often be solved by simply removing excess soil back below the damp-proof course - this would be the case if a raised flower bed was the culprit for example. When a more permanent fixture or alteration has bridged the damp proof course, a damp proofing solution that adapts to your property will likely be required. A qualified surveyor will be able to make the best recommendation.

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 to correctly diagnose and treat this 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 professionals.

Buying a House with Rising Damp

If you are interested in a property that has rising damp 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.

Contact the 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.

Our team of experts will assess and correctly diagnose the extent of your rising damp issue. From this, we provide recommendations on specific damp proof treatments for the most effective ways to treat your 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.