We’re the only damp-proofing company that offers a 50-year guarantee.
We are damp-proofing specialists, and provide a full range of services:
For an explanation of each of these treatments, please click or scroll down.
First, let’s quickly run through the basics of damp-proofing.
Let’s start with the humble brick that’s used to build a typical house.
Despite appearing hard and solid, a wall-brick is like a sponge, soaking up ground water through the porous fissures that permeate it.
A wall will generally absorb water to the point where the natural evaporation equals the capillary forces acting through the brick – we’re talking to a height of about 1.2m, depending on the size and porosity of the brick.
This is rising damp.
To arrest the upward movement of water, some sort of impervious material needs to be put in its way. Like a rubber sole on a shoe, a damp-proof course (DPC) simply stops water’s amazing capacity to rise up against gravity.
A DPC can be made of all kinds of materials, such as bitumen-soaked hessian, high-grade plastic, slate, a chemically injected solution, or even metal… It’s not rocket science. It’s just that the layer has to be waterproof and ideally, not degrade before the life of the building is up.
Perhaps surprisingly, the vast majority of the buildings we deal with involve buildings where this waterproof layer has been breached, rather than failed. In other words, some sort of works, be it interior or exterior, have allowed water to by-pass the membrane. Bear in mind, it’s not uncommon for material like bitumen-soaked hessian or plastics to degrade over time and thus allow water through again.
When we come to do a survey, we’ll find the problem. And usually we are able to fix any breaches relatively easily and cheaply.
A damp-proof membrane (DPM) performs a similar impervious function, though in this case, it’s generally just a DPC on a larger scale. It could go under a solid concrete floor, up a retaining wall and perhaps, rather confusingly, could actually be incorporated as the DPC itself.
No matter what, the key point is that a DPC or DPM is an impervious layer made of something that can stop water moving into the home.
Chemical damp-coursing is where chemicals are injected into the brickwork. This makes the layer of brick impervious to water and prevents moisture from rising.
The injection is done along the mortar joint at the base of the wall until the entire depth of the brickwork has been impregnated.
Since physical damp-coursing is more expensive (although much more effective), many people choose chemical damp-coursing as a cheaper alternative.
There’s one important thing to consider. With the failure of the original DPC (or if one isn’t present at all), ground salts will inevitably have risen into the wall. This means the wall will not dry out completely unless damaged plaster is removed and replaced by a specially formulated salt-retardant render, such as our unique DR5.
Plaster is usually removed to a height of 1.2m, although it could be higher depending on the type of ground salts and other factors.
Further information regarding our specialised render system can be found under Specialist replastering. Following these works a final skim coat will be applied to provide a smooth finish.
From our sixty years of experience it’s perfectly clear to us that a physical DPC far out-performs its chemical equivalent. No question.
Although other ‘breakthroughs’ in damp-proofing have developed in the industry over recent years, when it comes to performance and durability they simply cannot beat the physical option.
We’ve lost count of the times where customers have paid for multiple chemical injections only to find that they have failed and now demand the ‘real’ solution.
The Building Research Establishment, in its Digest 245, confirms that a physical DPC is the only completely sure method to cure rising damp. And Dampcoursing Ltd is happy to back-up its system with a 50-year guarantee.
This method of damp proofing is suitable for brick or stone walls (or a combination) where existing damp courses have failed, or where a DPC was never installed at all.
A central void filled with rubble may also be part of the construction, so this is another area where physical damp proofing offers many more benefits than a chemical alternative.
Specialist cutting equipment is used to create a horizontal groove along the wall. Working in 1m sections (or less, depending on circumstances) at a time, operatives then place a damp proof course in the groove, bedded on mortar. Slate spacers are inserted along the section to support the wall and compress the bedding mortar as we work.
The mortar course is then repointed the entire length of the work to create a finished job.
Brick wall thicknesses of up to 1m can be achieved, even if composed of a random course stone construction. We are usually able to overcome any technical issues arising from different types of wall composition.
In over 60 years, we’ve never once had to go back to repair a physical DPC that we’ve installed. They’re that effective.
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In general, structural waterproofing refers to damp-proofing areas of a building where water ingress (entry) is a problem.
As the name suggests, some sort of structure is required to hold back the pressure of water trying to get into the property. Alternatively a method of channelling the water away from the property can be used, together with a damp-proofing solution.
Also known as cellar waterproofing or cellar tanking, our service can turn your cellar or basement into a dry, habitable and usable space.
It’s essential to identify the correct tanking method for your property.
But with the correct solution you can be assured of a highly effective waterproof system for basements, cellars, under-street vaults, lower ground floor rooms, and garden flats.
There are four basic types of tanking:
Cavity membranes are essentially DPMs that remove ground water pressure by allowing water to be channelled either into a natural drain, or to a sump, where the water is pumped to some sort of natural drain. These membranes are often also used in areas where removal of water isn’t necessary, but where a cost-effective and insulative solution is recommended.
Cementitious coatings, often also known as slurry tanking, can be a cost-effective solution, depending upon the extent of water pressure and the durability demanded. Though, as the name suggests, the base structural compound is cement, these products have a great number of additives to ensure that a water-resistant, structural coating is created. We will normally apply between 3 and 5 coats, depending on the resistance required.
Liquid applied membranes are tough, epoxy resins usually comprised of two materials that are mixed on site, and forms a kind of tough impervious glue. This creates an effective DPM for a floor area, and can be incorporated with a new DPC to the walls to create a water-proofed area.
Multi-coat renders can be used in basement areas that have previously been infected by salt contamination, perhaps due to flooding or some unique event that’s not expected to recur.
In other instances, where continuous condensation cannot be eradicated, it may be appropriate to put in place a ventilation solution, together with our specialist render to ensure a clean and dry environment.
Eradication of dry rot is a specialist task that needs to follow a strict operating criteria. Dampcoursing Ltd’s expertise in this field is second-to-none.
The decay of timber due to wet or dry rot happens when it’s in contact with damp surroundings i.e. rising damp, plumbing leaks, leaking gutters or even unventilated sub floors.
Prior to the commencement of any specialist treatment, the affected area is fully exposed before a second survey takes place. Dry rot is caused by moisture, the source of which must be identified and rectified as soon as practicably possible.
Initially, we concentrate on ensuring the rapid drying of any damp masonry prior to reinstatement work, and take measures to ensure this damp never reoccurs.
All concealed and embedded timber surfaces adjacent to an outbreak – including timber lintels, bressummers (load-bearing beams), trimmers and adjacent concealed joinery surfaces – are then exposed and examined for the presence of dry rot and replaced as necessary.
Wet rot is usually less costly than dry rot, as the method to eradicate the growth is easier and normally does not involve a chemical treatment.
However, the source of moisture will need to be identified and eradicated and any replacement of damaged timbers will be required.
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Infestation is often found in damp buildings as their framework can be a good food source for woodworm and boring beetles.
The correct identification of a particular insect is required so as to ensure the correct treatment is applied.
Specialist replastering is nearly always a necessity when dealing with rising damp.
A new damp proof course will prevent further moisture rising into the wall. However the existing problem will have usually allowed soluble salts from the brickwork and groundwater to infect the plaster. Once there, these salts effectively prevent the existing plaster from drying out, as any condensation will be readily absorbed by the salts, thereby causing effervescence at the surface. A new salt retardant render needs to be applied, such as our unique DR5 premix.
Dampcoursing Ltd’s DR5 render is specially manufactured to our own specifications, containing selected grades of sand with the correct amount of cement. Each batch is tested at the factory to ensure strict uniformity. Together with waterproofing additives that conform to BS 1881, we can ensure a product that – together with a new DPC – will give long lasting results.
Most other renders that are hand mixed on site, without proper testing, contain micro-fissures. These tiny fissures can’t be seen, but they provide a route for moisture to travel through, meaning the damp-proofing can fail.
Our DR5 premix is carefully blended and forms a very important aspect of our damp-proofing works. Even where clients arrange their own plastering, we insist that our products must be used to our specification in order for the guarantee to be effective.
Two or three coats are applied, depending on whether the wall is above or below ground level. Replastering is carried out to a minimum height of 750mm, though more usually 1.2m – and certainly to a height beyond the last visible signs of contamination.
After application of our DR5, a final finish coat completes the process.
Call us now: 020 8802 2233