Damp in older Northumberland homes: finding the real cause

Damp is one of the most common worries for owners of older houses in Northumberland – and one of the most often misunderstood. Too many homeowners are told they need a chemical damp-proof course when the real problem is a blocked gutter, a raised flowerbed or cement render. This guide explains how to think about damp, so that money is spent on the cause rather than the symptom.

First, look at where and when

Damp leaves clues. Where it appears, its shape, and when it gets worse all point towards a cause:

• Patches high on walls or around windows that get worse in wet, windy weather usually point to rain getting in.
• A tide mark low on walls may be ground moisture – or rain splashing from a hard path, or a bridged damp-proof course.
• Black mould in corners and behind furniture, worse in winter, is usually condensation.
• A damp patch that appears suddenly may be a plumbing leak.

The common causes

Rainwater

Overflowing or leaking gutters, downpipes that discharge against the wall, failed pointing, cracked render and defective flashings are the most common sources of damp we find. In exposed parts of the county – the coast, and higher ground – wind-driven rain makes these problems worse.

Ground levels

Over decades, paths, patios and flowerbeds are often built up against walls, sometimes above internal floor level or the damp-proof course. Lowering them, or forming a drained gravel strip, can make a dramatic difference.

Trapped moisture

Solid walls need to dry out. Cement pointing, cement render, gypsum plaster and modern vinyl paints can all trap moisture. Removing them and repairing in lime is often part of the long-term solution.

Condensation

Everyday life puts a lot of moisture into the air. If ventilation is poor and walls are cold, it condenses. Extractor fans, trickle vents, consistent heating and, where appropriate, breathable insulation reduce it.

Leaks

Pipes under floors and inside walls can leak unnoticed for a long time. A moisture pattern that does not match the weather is a clue.

What about rising damp?

Moisture can rise from the ground into walls, but true rising damp is less common than often claimed, and solid stone walls were never built with a damp-proof course in the first place. They manage moisture by letting it evaporate. Making sure they can do that is usually more effective than trying to block moisture with chemicals.

A sensible order of work

1. Fix rainwater goods and obvious leaks.
2. Lower external ground levels and improve drainage around the house.
3. Remove harmful cement pointing, render and impermeable coatings where needed.
4. Improve ventilation and heating patterns.
5. Give the walls time to dry, then repair plaster in breathable materials.

When to get help

If damp keeps coming back, or you are buying an older house with a damp report recommending chemical treatment, it is worth getting an independent view. We are happy to look at damp problems in older homes across Northumberland and explain what we find.