Damp can have many causes and many negative effects. In addition to the physical structural damage to your property, damp can also cause bad odours, mould, and rot.
As winter closes in and you and your family once again have to endure the typically wet weather of the UK, it’s not too late to think about reducing the condensation levels in your home and have some damp proofing installed in your property. Damp proofing can be fitted via a variety of different building techniques, from wall injections and plaster board application to ordinary draught protectors. Plus the damp course cost in your local area might not nearly be as much as you might think!
Nevertheless, the cost of damp proofing varies considerably according to a number of different factors, including the extent of condensation and damp already affecting the property; whereabouts in the country you live (due to potential weather and climate conditions that might affect future completed work); how much of the home needs fitting with damp-proofing measures; the size of your property; and whether or not you’ve had such measures fitted before. So exactly how much does damp proofing cost? And how much does a damp proof course cost compared to more complicated measures and techniques?
What is damp
Damp is proven to be one of the most difficult and troublesome of household problems and many home owners struggle to deal with it. The appearance of damp may suggest some sort of internal leak in your pipe or guttering system that needs to be located and fixed or condensation problems. Left untreated damp can cause various forms of mould and fungi to thrive on the inside of the building, which can result in an infestation of mites or even put you and your family at risk of serious respiratory illnesses and infections.
Damp is usually caused by excessive condensation; water penetration into the plaster and brickwork of internal walls extracts salts which appear as unsightly white deposits known as efflorescence. The leaks also result in unattractive ‘tide marks’ appearing on the interior side of the wall, which can often spread rapidly and severely damage the structure and safety of the wall itself. Damp also rots wooden fittings and furniture and can loosen wallpaper, plaster and paintwork.
Penetrating damp is caused by rainfall seeping into houses due to poor roof maintenance and repair, gutter blockages and overflows, and various other points where water can enter. This water seeps into the structure of the building and the timbers and can cause significant damage. This type of damp shows as large patches or stains on walls, ceilings and floors, particularly after heavy rains.
Internal spillage occurs when a bath or sink overflows or an appliance such as a dishwasher or washing machine leaks. Damaged and burst pipes and geysers also result in internal spillage.
Below ground damp causes what is sometimes called rising damp. Moisture in the ground evaporates but is impeded by the impervious coatings used in building, causing the water to drain towards the perimeter walls, where it soaks up through the brickwork by capillary action. This can also be affected by fluctuations in the water table beneath your property. The rising damp caused by below ground moisture can leave a tidemark on the walls indicating salt deposits, although there is seldom mould growth.
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What causes damp in the house
There are many causes of damp and rising damp. They include high humidity or excessive condensation levels in the home, combined with poor ventilation and/or faulty drainage facilities. The appearance of damp often indicates a multitude of problems rather than a single source, but there are still several causes of damp you can look out for to help reduce the risk of it taking over your home:
Closed doors and windows
If you keep your windows and closed they trap heat and regularly result in the build-up of excessive moisture and consequently mould and damp.
Prevention: To prevent this from occurring, remember to keep the home well aired; even in the cooler winter months doors or windows should be opened for at least an hour a day.
Baths and showers
Excessive amounts of baths and showers can also result in a build-up of humidity, which – if lacking an escape route – also ends up manifesting as damp or mould in the property.
Action: remember to keep bathroom windows open for as long as possible and try to stagger showers throughout the day if you can.
Over usage of electric appliances
Over-using electrical appliances, such as the oven, washing machine or dishwasher can result in large amounts of heat being produced in a relatively short amount of time, especially if they are all used at the same time.
Action: To keep heat levels down stagger appliance usage and remember to turn everything off after use.
Drying clothes indoors
Drying clothes indoors, such as on radiators or ‘clothes-horses’ can increase the moisture levels in the home too, especially if the heating is on.
Action: Try to hang washing outdoors whenever you can, as even cold winds will dry things quicker and more effectively while also reducing the humidity in the home.
Check your damp proof
Make sure your damp proof course (DPC) is in good condition. A DPC is a thin layer of waterproof material which is inserted horizontally near the bottom of a building’s structure to prevent damp rising up through building materials. Liquid DPCs can also be injected into the walls of your home by a damp treatment specialist.
Action: A defective damp proof course is a major cause of rising damp, so make sure yours are in good condition.
Most common causes of damp
Any small drops from plumbing could result in a big and intense wet spot and even though the escaping water might be small, it is usually consistent and concentrated in the same location. The concentrated and repeated moisture build-up gets to a point where it is totally saturated and the excess water leaks to the surrounding areas. Damp in the home could be a result of tiny fractures in the bathroom wall tile grout, especially if combined with ‘power showers’.
If there is a gutter leak at the eaves, water will flow on the wall’s exterior a short distance or it might splatter below onto the window sills or the ground. Water is usually fed into the roof space via leaks from other gutters and they are usually very challenging to pinpoint.
Holes in roofs
This is usually a result of slipped or missing slates or tiles. It might also be due to thatch that is worn, or a damaged slate or tile.
Climate change or roof upgrades to your home since it was initially built could mean that gutters aren’t big enough to deal with the increase in rainfall. The two solutions are to install bigger capacity gutters or add more downpipes.
Grooves under window sills
Most buildings from the mid-17th century depended on windows with outside sills that extend beyond the wall face. There is a groove on the window sill’s underside that directs excess rainwater beyond the wall. Blocked grooves result in the rainwater pouring down the outside of the window and that water will go directly into the wall right under the window.
Chimney stacks and roofs
This is another area of vulnerability that could allow water to seep into the walls.
Aged downpipes made from cast-iron can become rusty on the back and it can remain unseen. Also, downpipe that run directly into the ground or that have sharp turns are susceptible to blockage from gutter debris.
Remove all climbing plants because they can attract damp and prevent walls from fully drying.
Check for broken gutters or downpipes outside to see if they are causing leaks that could be letting water into your home. Increased internal moisture often causes damp which, once it takes hold, can be extremely difficult to deal with.
What is damp proofing?
Most often damp proofing is effected by installing or DPCs, a barrier designed to prevent moisture from penetrating your walls and floors. Other methods include application of a paint-on preparation that seals the surfaces. There are also instances of porous ceramic tubes, 50mm in diameter, being inserted into a wall. The theory is that these tubes will collect the damp and allow it to evaporate, but they can be unsightly and there are often problems in application.
Some of the damp proofing methods employed are extreme and require structural alteration to your house.
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How is the DPC Inserted into the wall?
There are different methods for installing DPCs. In some cases, the DPC is inserted by cutting into the wall or during rebuilding. This can be effective, but it can also result in structural problems and damage to internal finishes, especially where these are custom or antique.
There are chemical damp proofing course solutions available which are injected into holes drilled into the wall. This method is quite widely used today, but it cannot always be applied in older buildings. The cost of chemical DPCs is around £195/m, which includes the cost of re-plastering the holes through which the mixture is applied.
How much does damp proofing cost?
On average estimate to pay£60 per linear metre + vat. So for an average-sized living room of 4 x 4 metres, you should expect to pay around £270 + vat per wall.
The table bellow details damp proofing costs for dealing with common damp situations. These costs are obtained from survey we conducted across our network of tradesmen. The costs include everything necessary to carry out the work including labour, material and VAT.
|Problem: Ground level is above the existing damp-proof course (DPC)|
|Solution: It is necessary to excavate the soil to make sure that the ground levels is at at least 15cm bellow DPC.|
|Work needed||Terraced house||Semi-detached house||Detached house|
|Soil excavation of one wall||£200||£290||£450|
|Whole house soil excavation||£330||£540||£1,300|
|Soil excavation and laying new gravel path (one wall)||£270||£395||£585|
|Soil excavation and laying new gravel path (whole house)||£350||£820||£2,000|
|Soil excavation and laying concrete paving slabs (one wall)||£400||£690||£1,400|
|Soil excavation and laying concrete paving slabs (whole house)||£760||£1,890||£4,190|
|Soil excavation and laying 10cm thick concrete path (one wall)||£430||£750||£1,190|
|Soil excavation and laying 10cm thick concrete path (whole house)||£850||£2,110||£4,040|
|Problem: Non-existent or damaged DPC|
|Solution: Create a damp barrier with silicone or insert new DPC|
|Work needed||Terraced house||Semi-detached house||Detached house|
|Damp proof silicone Injection (one wall)||£490||£760||£2,000|
|Damp proof silicone injection (whole house)||£900||£2,100||£4,700|
|Insert new DPC (one wall)||£290||£425||£610|
|Insert new DPC (whole house)||£395||£920||£2,060|
How to save money on damp proofing
Quote: Serious damp issues can cost as much as £16,000 to rectify. But, thankfully, there’s a lot you can do to identify and fix the problems yourself, before resorting to professional help. Which?
Ideally, damp prevention measures should be put in place during the building stages, but this is obviously not an option in existing homes, especially in older and period houses.
If you do discover a damp problem in your property, the first step towards ensuring that you are treating the problem correctly would be to determine the actual cause of the damp. Oftentimes an expensive and intrusive solution is recommended when a simple, cheap one would be as effective.
- Ventilation: If the damp is caused by condensation, it could be a simple matter of improving the ventilation in your home.
- Windows and doors: By allowing air flow could help significantly. Installation of extractor fans in high moisture areas such as kitchens and bathrooms can also make a big difference.
- Insulation: Proper insulation can also go a long way towards preventing condensation in your home.
- Gutter maintenance: Your should at least repair and maintain your gutters out at least twice a year to ensure that there are no blockages or leaks that can cause overflow into the structure of your house.
- Roof injections: Roof junctions are often areas where leaks can occur, and resealing these areas can prevent leaks. Replace missing or broken roof tiles before leaks can cause damage to roof timbers. Re-point any mortar that needs it to prevent cracks and holes forming where water can get in.
- Source of water: The same principle applies to damp caused by internal spillage. Often removing and repairing the source of the water will solve the damp problem without the need for drastic and expensive measures.
- Lime plaster: Future damp problems can also be prevented by using lime plaster instead of the anti-sulphate or renovating plaster that is normally use. Lime-based plaster allows greater breathability, which aids evaporation and decreases the chances of damp build up.
- Drainage: Proper drainage in the ground surrounding the house can also prevent below ground damp, especially in basements and cellars. French drains can be effective for this purpose, but need to be set up properly to avoid compounding the problem.
Rising damp is often the most difficult and expensive to fix, as the damp has permeated the walls and floors deeply and can be difficult to fully remove. However, investigations have shown that this damp is actually far less common than popularly believed. Often what is diagnosed as rising damp is only condensation, and can be solved as described above. Make sure that you know exactly what type of damp you are experiencing before embarking on an expensive damp proofing solution.
Who should do the damp proofing?
If you have investigated your damp problem thoroughly and have found that it is not a simple matter to solve, it is time to call in a damp proofing professional. It is always a good idea to approach more than one company, though.
Investigate and research damp solution companies, and wherever possible obtain references and recommendations from previous customers. Try to get at least three quotes from three different firms. Some companies will make unnecessary recommendations for treatments and solutions that are very pricey. If you find that they all make different recommendations and give very diverse prices, it is a good idea to contact a damp proofing specialists.
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