INTERNAL DAMP

off the supply of water. Check for things like blocked or overflowing gutters, leaking downpipes, faulty drains or gulleys, and waste pipes that need to be fixed.

The most common cause of damp in lower walls however is high ground. External ground levels should be a good 200mm or so below floor level. Common offenders include flower beds banked up against outside walls that effectively force moisture into the brickwork. Other culprits include patios laid far too high causing bridging of DPCS, and rain splashing on hard surfaces that saturates the lower walls. As well as lowering the ground, installing a shallow gravel-filled trench around the base of the walls should allow moisture to evaporate more easily.

Modern cavity walls can also harbour damp due to poor quality construction with mortar droppings or debris accumulating in the lower cavities which may need to be cleared by specialist contractors laboriously removing individual bricks. If all else fails and an injected DPC is recommended, the most effective option is a diffusion system using Silane cream which is odourless, nonflammable and diffuses via the mortar joints without scarring the walls, so can even be applied to party walls.

There are no prizes for guessing which room in a typical home is most likely to harbour unpleasant damp smells. Bathrooms have multiple weak points that can wreak havoc over time. For example, mastic seals around the edges of baths and showers are prime candidates for allowing water to seep through, and shower trays are notorious for springing leaks. Hairline cracks in the grouting to bathroom wall tiles combined with power showers are another classic recipe for damp. And that’s before you consider the hidden horrors of DIY pipework where small leaks can remain hidden over time until timber decay has taken hold resulting in suspiciously soft and springy floors.

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