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Damp Proofing – How Much Does It Cost?

Last Updated on December 16, 2019 By Dave

Damp in homes is a very common problem. It’s surprisingly easy for conditions to develop which enable and even accelerate its progression. In fact, it’s increasingly rare to find long term renters who haven’t experienced some degree of damp in a property. That’s how common it is. Yet, just because an issue is familiar, doesn’t mean it’s safe.

The advice for anybody with damp in their property, be it rented or owned, is to take steps to remove it immediately. In most cases, this means calling in a third party expert. Although it is possible to ‘treat’ damp and mould growth with home remedies, the results are always temporary. The only way to permanently eliminate damp is to fully repair the root cause.

Depending on where the residual moisture is coming from, this can be a quick or lengthy process. However, if it’s done correctly first time, it will be difficult for the damp problem to return. So, it’s worth investing in high quality damp proofing particularly if you already own your property and would like to sell it one day. Damp is one of the number one reasons prospective buyers reject homes.

Identifying the Cause of Damp Problems

The fastest way to diagnose a damp problem is to hire a property surveyor who can inspect your home for damage. Before you do this, however, you might want to carry out your own investigation. Some causes are more serious than others. Rising damp, for example, can indicate a problem with your property’s foundations. Surface level damp around doors and windows, on the other hand, may be caused by poor ventilation and easily fixed.

The more you know about the issue before hiring a contractor, the more efficiently you can communicate and negotiate a fair rate.

Rising Damp

Some symptoms of rising damp (moisture from the ground) include visible water droplets on interior walls. You may notice a wall looks wet and feels damp or slimy to the touch. As this type of damp progresses upwards from the foundations to a higher and higher position, you may notice stains and marks appear on the wall. These stains are sometimes referred to as ‘tide marks’ and are normally yellow or brown in colour.

Once these tide marks start to appear, it’s time to start worrying about the health of your home’s brickwork and plaster. This type of damp suggests a break in the seals designed to keep walls and floors separate from the moist, earthy ground. If you do not fix the seal and restore your property’s damp proofing, materials in the walls and floors may begin to rot.

In some cases, penetrating moisture does not originate from the floor at all. If offending watermarks and stains are unusually high up on a wall (over 1.2 metres), there is a chance the damp is being caused by a leak in the roof. The best way to know for sure is to hire a roofing specialist for an inspection.

Finding the Root Cause of Your Rising Damp Problem

While waiting for help from a professional surveyor or damp proofer, there are some things you can do to investigate the problem.

Look at the Damp Proof Coursing

All modern properties are supposed to be built with what’s known as damp proof coursing. You can spot this from the outside of your home. It runs around the perimeter of the property at approximately six inches from the ground.

It doesn’t look like much, but you’ll notice a subtle division or visible transition at precisely this height (sometimes it’s a pale grey line, other times it’s a slightly protruding section of brickwork). Damp proof coursing is a layer inserted in the walls to prevent groundwater from rising above a certain point. If you have recurrent issues with rising damp, it’s probably because the DPC layer does not exist or is failing.

Check for ‘Accidental Bridges’

When the DPC layer works, it allows groundwater to rise up walls only to a certain point. However, if water is entering the property above this point, damp proof coursing is largely ineffective. The most common example is in properties with basements. The DPC layer is higher than the basement level, therefore, the water doesn’t need to pass it to infiltrate.

Another example is residual moisture from trees and shrubs in touching distance to the property. If a shrub is constantly wet and growing right against the wall at a fair height, any moisture can just bypass the DPC. It’s worth taking a look around the perimeter to check for ‘accidental bridges’ like these.

Though it’s less common, problems with an adjoining neighbour’s property (and their damp proof coursing) can lead to the same issues. Be aware of this possibility when carrying out your damp investigation.

Taking the First Steps to Cure Damp in Your Home

As already mentioned, there are lots of ‘DIY’ recommendations for homeowners trying to eliminate damp from their properties. Many of these are effective in the short term. Unfortunately, there is no permanent way to cure rising damp without fixing its root cause. This may require some repair or renovation work and should certainly include a high quality damp proofing service to prevent future recurrences.

The probable cost of a full damp proofing service for a property depends on its size, the severity of the damp and any aggravating circumstances (for example, multiple leaks are discovered). Average cost will also be influenced by where you live. Damp proofing services in the south of the country tend to come with higher fees. Property owners in and around London routinely pay 20% more than those in the north.

Typically, damp proofing for a single wall in a terraced home costs around £180. However, having the same property fully damp proofed would likely cost just £300. Semidetached properties are slightly pricier with an estimate of £250 for a single wall and £550 for the whole house. Finally, a fully detached home can cost around £1,500 to fully damp proof.

We’d like to stress these figures are estimates. If there are dysfunctions within that all important DPC layer, additional repair work will be required. For properties without a discernible DPC, a chemical filler can be inserted which replicates the missing layer. It’s an effective fix but it usually costs extra on top of the damp proofing fees.

Depending on the size of the property, inserting this new DPC layer can cost anywhere between £400 and £2,200 for an entire perimeter. Single walls are more affordable at approximately £250 to £400 but one treatment for one wall may not be enough to eliminate your damp problem for good. This is why it’s so important to consult with an experienced surveyor who can determine the true extent of the issue.