Damp Surveys in Liverpool

Why get a damp survey before treatment?

Damp is easy to misread. A tide mark low on a wall can look like rising damp when it is really a bridged damp proof course, a leaking pipe or condensation running down a cold wall. Mould in a bedroom corner might be condensation, or it might be water getting in through a defective gutter above. Each cause needs a different remedy, and the wrong one can cost a lot and leave the problem in place.

Rising damp in particular is often over-diagnosed. Many cases we see are caused by something simpler — raised ground or path levels outside, render or plaster taken down over the damp proof course, or debris bridging it — which can sometimes be corrected without injection. A careful survey is how you find that out, and it is the first step in any mould and damp treatment across Liverpool that we carry out.

What does a damp survey include?

1. Background. We ask how long the damp has been there, whether it changes with the weather or the seasons, what work has been done before, and whether the home is owned or rented.
2. Inside inspection. We look at every affected room: where the damp sits, its shape and height, staining, salts, blown or soft plaster, mould growth, skirting boards and floors.
3. Readings. We take moisture and humidity readings and compare affected and unaffected areas.
4. Ventilation and heating. We check extractor fans, trickle vents, door undercuts and heating patterns, all of which bear on condensation.
5. Outside inspection. From ground level we look at gutters, downpipes, pointing, render, sills, ground and path levels against the wall, and any visible damp proof course.
6. Findings and quote. We explain what we found and why, with photos, and give a written quote. Where outside repairs are needed — roofing or brickwork, for example — we say so clearly, as these may need a roofer or builder.

How reliable are damp meter readings?

Most handheld damp meters measure electrical resistance and are calibrated for timber. On plaster and brick they only give relative readings, and they can be fooled by salts, foil-backed wallpaper, condensation on the surface and some paints. A high reading on its own does not prove rising damp.

That is why we read the pattern of the damp alongside the building itself. Where the cause is still unclear, more reliable tests are available, such as taking drilled samples of masonry and testing them (the calcium carbide method). We will explain if we think further testing is worthwhile and why. The relevant British Standard for diagnosing rising damp and installing chemical damp proof courses is BS 6576.

What can a damp survey find?

• CondensationMoist indoor air settling on cold surfaces, usually shown by mould in corners, on window reveals and behind furniture. Fixed with ventilation and condensation control.
• Penetrating dampWater getting in from outside through walls, roofs, windows or failed seals, typically worse after rain.
• Rising dampGround moisture drawn up masonry without an effective damp proof course, with a tide mark and salts. See rising damp treatment.
• Plumbing leaksSlow leaks from pipes, radiators, waste pipes or shower trays, often mistaken for other kinds of damp.
• Timber decayWet rot or dry rot in skirting, floor joists or window frames where timber has stayed damp.
• Salt-damaged plasterOld plaster holding hygroscopic salts that draw moisture from the air, even once the original cause has been fixed.

Damp surveys in Liverpool’s older housing

Liverpool’s Victorian and Edwardian terraces have solid walls, many have cellars, and many have had decades of alterations: back extensions, replacement windows, new floors, rendered or painted fronts, raised yards and paths. Each change can affect how a wall gets wet and dries out. In streets of older terraces across Toxteth and Old Swan we regularly find more than one cause at once. Larger Victorian houses in Aigburth, often converted into flats, add cellars and shared walls to the picture.

Inter-war and post-war homes have cavity walls and usually fewer cellar issues, but condensation, leaks and ventilation problems are common there too.

Damp surveys for landlords and letting agents

If you let a property, a written record of the cause of damp, the work proposed and the work completed is valuable. We provide clear notes and photos that landlords, agents and housing providers can keep on file and share with tenants. Damp and mould growth is one of the hazards assessed under the Housing Health and Safety Rating System, so understanding the cause early helps everyone. For more on private lets, see our landlord damp and mould page.

What affects the cost of a damp survey?

The cost depends on the size of the property, how many rooms are affected, access to the outside walls and cellar, whether further testing such as drilled samples is needed, and whether you need a written report for a landlord, agent or buyer. Our damp and mould cost guide explains how treatment costs build up afterwards.

How to prepare for a damp survey

• Note when you first noticed the damp and whether it gets worse after rain or in winter.
• Keep any paperwork from previous damp work, such as old DPC treatment records.
• If you can, clear a little space along affected walls and give access to the loft and cellar.
• Photos taken at different times of year can be very useful.