Tenement Damp: Why the Standard Answer Is Usually Wrong

A reading is not a diagnosis

You have a tide mark along the bottom of a wall, peeling paint above the skirting or a blistering patch of plaster. A damp-proofing company visits, presses a handheld meter to the wall and quotes for an injected damp-proof course. In an Edinburgh tenement that quote deserves a second look before you sign.

Historic Environment Scotland puts it plainly in its Inform Guide, Damp: Causes and Solutions. It says damp is often misunderstood in older buildings, and that proposed solutions can be expensive, damaging and misguided because they treat the symptom and not the cause. It adds that tanking, waterproofing, rot treatment and injected damp-proof courses are often recommended without addressing the cause, and that in many cases they are unnecessary.

How a tenement manages moisture

A traditional Edinburgh tenement is typically solid stone, often bedded and pointed in lime, with lime plaster inside and no cavity. Historic Environment Scotland describes traditional buildings as managing moisture through permeable materials such as stone, lime and timber, together with sound roofs, drainage and detailing. When that ability to breathe is lost, moisture can build up in the wall.

So the useful question is what has changed in this wall, not which product to apply to it.

What is often behind it

These are the causes that recur in the official guidance. More than one can act at once.

• Failed rainwater goods. Historic Environment Scotland says overflowing water from a blocked downpipe can quickly saturate masonry, and that a defective parapet gutter leaks directly into the wallhead. On a tenement these are usually shared parts, so the repair is a common one. See our note on blocked shared repairs.
• Cement pointing and render. Historic Environment Scotland notes that cement is often blamed, and that sound cement render on a dry wall may not be the problem. Cracked or defective cement lets water in and sharply cuts the wall’s ability to dry out.
• Leaking pipes and overflows. A mains pipe, heating pipe or waste leak can feed a wall for a long time. In a tenement the source can be in a neighbour’s flat or in the shared pipework.
• Blocked sub-floor ventilation. Suspended timber floors need clear grilles at the base of the external wall. Historic Environment Scotland says air movement under them should stay open, and that they should generally not be replaced with a concrete slab.
• Condensation. RICS explains that water vapour condenses on the coldest surfaces when rooms are cold or humid, and that drying washing and poor kitchen and bathroom ventilation add to it. Historic Environment Scotland also warns that loft insulation can cause condensation in a colder attic unless it is ventilated.

Why a meter reading does not settle it

Handheld meters are quick, which is why they are used. SPAB, the Society for the Protection of Ancient Buildings, says rising damp is widely misdiagnosed from high electrical meter readings alone, and that readings can be high in old buildings that are not unduly damp. Salts in the masonry are one reason, and RICS lists others. A single reading cannot tell you why a wall is damp.

What a proper investigation looks like

In 2022 RICS, Historic England and the Property Care Association produced a joint position statement on investigating moisture in traditional buildings. It asks for a holistic diagnosis that deals with causes, not symptoms. In practice that means looking at the whole building, including the outside and the roof, before any treatment is chosen. SPAB’s technical advice on the control of dampness describes further testing, where needed, by taking samples from the wall (carbide or oven-drying methods) and monitoring humidity over time. Those methods take longer than a meter visit and can be intrusive.

Guarantees

The Property Care Association says many of its contractors can provide an insurance-backed guarantee. Ask exactly what the guarantee covers and when it pays out, because an insurance-backed guarantee exists mainly for the case where the contractor stops trading. A guarantee on a treatment does not show that the treatment suited the cause.

Questions to ask before you sign a damp quote

1. What caused the damp, and how do you know? Was the whole building inspected, including the outside?
2. What did you measure beyond a handheld meter?
3. Were rainwater goods, pointing, render, pipework and sub-floor ventilation checked?
4. Why is this treatment the answer to that cause?
5. What does the guarantee cover, who stands behind it, and what voids it?

An independent surveyor with conservation experience can answer these in writing. The RICS consumer guide to damp and mould explains how to ask for a survey that follows the joint statement.

Where a refurbishment fits

We are a refurbishment contractor. We do not diagnose damp or sell damp treatment. During kitchen, bathroom and whole-flat projects we open walls, and we pass on what we find so that your surveyor, or the owners responsible for the shared parts, can act on it. If you suspect damp, get the cause diagnosed first, then bring us the work that follows from it. For a recurring problem, read why damp keeps returning in Edinburgh tenements, and see how we run tenement renovation projects.

If your project involves opening up walls or floors, tell us about it and we will say what we need to see before we price it.

Where an established investigation informs a wider refurbishment, our home renovation service in Edinburgh explains the construction scope. The renovation brief needs to follow the findings and specification; it does not replace the investigation.