Damp surveys in Derby

What a damp survey should actually establish

There are only a handful of ways water gets into a wall, and they call for completely different remedies. A survey worth paying for narrows it down to the right one:

• Condensation — moisture already inside the building, settling on cold surfaces. Solved by ventilation, heating and insulation, not by injecting walls.
• Penetrating damp — rain getting through the fabric via failed pointing, a cracked sill, a blocked gutter, a slipped tile or a bridged cavity.
• Rising damp — groundwater drawn up through masonry where there is no effective damp-proof course. Genuine, but much rarer than it is diagnosed.
• Plumbing and drainage escapes — a weeping joint or a leaking waste can mimic every one of the above.
• Construction and site issues — raised external ground levels, added render trapping moisture, a blocked subfloor vent.

Several of these regularly occur together. A wall can be cold because it is damp and damp because it is cold, and treating only one half leaves you with the problem and a bill.

How we survey

We start with what you have noticed, because the history matters. Damp that appears after heavy rain behaves differently from damp that is worst in January, which behaves differently again from damp that has been there since the extension went on.

Inside

We look at the pattern and height of the staining, the condition of the plaster, salt deposits, skirtings and floor timbers, and how the room is heated and ventilated. Moisture meters are used as one piece of evidence among several — a meter reading on its own tells you a surface is conductive, not why.

Outside

Most internal damp has an external cause, so the outside of the building usually matters more than the inside. Ground levels against the wall, air bricks, the state of the pointing and render, window sills and their drips, gutters, downpipes, gullies, roof edges and flashings.

Then the explanation

You get told what we found, what we think is causing it and what we would do about it, in plain terms. Where the sensible next step is a builder, a roofer or a plumber rather than us, we say so.

Who carries out the survey

A CSRT-qualified surveyor — Certificated Surveyor in Remedial Treatment, awarded by the Property Care Association. It is the recognised surveying qualification for this work and it covers damp, timber decay, and the legal and health and safety side of remedial treatment. Where work follows, it is carried out by technicians holding PCAQT, the Property Care Association's technician qualification in timber and damp.

That is worth asking about generally, and not only of us. Damp proofing is not a licensed trade, so anyone at all may describe themselves as a damp specialist. A great deal of the unnecessary injecting and replastering we are called in to look at afterwards was specified by somebody with no diagnostic qualification whatsoever.

Buying a property in Derby?

If a valuation or homebuyer report has flagged damp or timber defects, that is usually a recommendation for a specialist inspection rather than a diagnosis. It is worth knowing what you are taking on before you exchange — and worth knowing when the flag is precautionary rather than serious. See reports for lenders and mortgage valuations.

Older and period property

Derby and the surrounding villages have a great deal of solid-wall brick and stone built long before cavities and damp-proof courses. These buildings were designed to take up moisture and give it back — to breathe. Sealing them with cement render, gypsum plaster or impermeable paint traps moisture in the wall and often makes matters worse. Solid-wall damp usually needs an approach that works with how the building was built, not against it.