Your charming stone cottage or Victorian townhouse might hold historical whispers, but it could also harbour a modern menace: the ‘damp-proofing’ chemical injection scam. This predatory practice targets owners of older buildings, exploiting anxieties about damp and peddling a useless, sometimes harmful, "solution".
The Hype: Imagine a magic potion injected into your walls, creating an invisible shield against rising damp. That's the enticing picture painted by companies pushing chemical injection. They talk of guaranteed dryness, lasting protection, and a quick fix for all your moisture woes.
The Reality: This "magic potion" is often a cocktail of silicones and resins. It fails to address the root cause of damp, which can be leaky roofs, defective rainwater goods, condensation, hidden plumbing issues, high ground levels etc. Injecting chemicals can even make issues much worse by trapping moisture inside the walls, leading to timber rot and structural damage.
The Red Flags: Here's how to spot these damp-proofing scammers:
They sensationalize damp: Exaggerated claims of "rising damp epidemics" or "instant cures" should raise suspicion. Dealing with dampness is normally a staged process and often cannot be completely eliminated in older buildings. Instead, damp issues should be carefully examined by a qualified expert and managed appropriately, in direct proportion to the seriousness of the issue.
They skip proper diagnosis: No investigation of the many factors that could be causing the dampness, just an immediate diagnosis of ‘rising dampness’ and recommendation of chemical injections and/or re-plastering with hard cement plasters. Proper investigation should use a wide variety of specialist tools, techniques and experience (not simply an electronic moisture meter in isolation). True rising dampness is, in fact, very rare and often misdiagnosed to help sell such ‘damp-proofing’ works.
They push expensive packages: Prices can be exorbitant, and often include unnecessary plaster removal or re-plastering that further weakens the walls.
They offer unrealistic guarantees: Guarantees lasting beyond the company's lifespan are meaningless and often only cover the immediate area they have treated. Unfortunately, the nature of the impervious materials used means that dampness will, more often than not, simply worsen and spread out to adjacent areas (conveniently not covered by the guarantee).
One-trick ponies: Many of these companies only train their operatives to sell this one solution alone (chemical DPC and hard plasters) because it is financially lucrative for them to sell and easy to install. Be extremely aware of any company recommending such works in older buildings.
Before you fall victim to the damp-proofing scam:
Seek a qualified and experienced Surveyor: Choose a surveyor with expertise in traditional buildings, not simply a salesperson in disguise.
Understand the different types of damp: Rising damp (rare in most cases) requires different solutions than condensation, penetrating damp or plumbing issues.
Focus on addressing the source: Eliminate any sources of penetrating dampness externally (leaking roofs, rainwater goods etc.), improve ventilation and heating, check for plumbing leaks and ensure external ground levels are not too high.
Consider alternative solutions: Traditional methods like lime plaster or breathable membranes are often more effective and sustainable.
Why chemical DPC's often don't work:
Misdiagnosis: This is the primary reason such systems often do not work. In the main, from our experience damp issues are usually a result of either condensation, penetrating dampness or plumbing issues (or the use of such modern materials trapping dampness in older walls). A chemical DPC injection will not resolve such issues.
Poor design: Chemical DPC’s are often injected above the level of the timber sub-floors meaning, not only will the replacement DPC fail to provide protection to the timber floors, but will actually serve to further trap dampness to this area, increasing the risk of rot and decay.
Poor workmanship: To have any chance of success, injection should be into the mortar joints rather than the brickwork, otherwise any damp can bypass the injected bricks by the mortar. Despite this, the masonry in old walls is commonly injected, sometimes even into hard impermeable stonework such as flint. We've even seen them injected into traditional bungaroosh walls; a construction type they are completely unsuitable for.
Incomplete barriers: Even where the works are carried out and designed correctly (often not the case) there are known issues where the chemical fluids do not entirely fill the pores or provide a complete barrier (sometimes due to faulty workmanship but can be a failure of the chemical fluid system itself).
Trapping dampness: Older properties are designed to ‘breathe’ and need to allow for natural evaporation to take place to effectively manage dampness. Chemical DPC’s and hard-cement plasters/renders are impervious and trap dampness within the construction, inhibiting natural evaporation and often making issues much worse than before.
Due to the impervious nature of the associated internal re-plastering / tanking works that almost always accompany a chemical DPC injection, at first it may appear that these works have been successful. However, from our extensive experience, this is very rarely the case and the new internal finishes are often simply masking the damp issue. It is very common to see dampness pushing out past these new finishes and to adjacent surfaces (and hidden timber sub-floors) after the works have been completed. As mentioned above, the ‘damp-proofing’ companies will often exclude such dampness from the remit of their guarantee (even though it may well have been a direct result of the system they installed).
Remember, damp problems in older buildings require careful diagnosis and targeted solutions, not a one-size-fits-all chemical injection. Protect your historic home and your wallet by avoiding this deceitful scam. Spread the word, and let's ensure these "Damp Cowboys" don't leave their mark on any more cherished buildings.
Additional Resources:
The Heritage House: https://www.heritage-house.org/damp-and-condensation/case-histories.html
RICS Dampness Guidance: https://www.rics.org/profession-standards/rics-standards-and-guidance/sector-standards/building-surveying-standards/investigation-of-moisture-and-its-effect-on-traditional-building
Building Preservation Trust: https://historicengland.org.uk/advice/caring-for-heritage/industrial-heritage/setting-up-a-building-preservation-trust/
By sharing knowledge and promoting informed choices, we can build a future where 'damp-proofing' scams become a relic of the past, not a blight on our architectural heritage.