Stop Penetrating Damp

Posted on October 4, 2019 in Building Maintenance

Penetrating Damp

There are three main causes of damp: rising damp, condensation and penetrating damp. We will be focusing on Penetrating damp in this post. We will explain what could be causing your penetrating damp, from cracks in a wall to leaking gutters, and how to deal with them.

Before you can fix the penetrating damp issue, you’ll need to find out what is causing it. Once you have found the problem, you will be able to determine how easy it is to solve, and whether you want to fix it yourself, or get a professional in to fix it. In a recent survey it was found that only 22% of people tried to deal with it themselves.

What is penetrating damp?

Penetrating damp is caused when water travels through walls and/or ceilings. Penetrating damp can usually be identified by the appearance of damp patches on walls and/or ceilings, which can darken when it rains. Other signs of penetrating damp are:

  • Growing circles of damp on walls or ceilings
  • Blotchy patches on walls
  • Wet and crumbly plaster
  • Signs of spores or mildew
  • Drips and puddles

This type of damp can spread across your walls or ceilings, and unlike rising damp, it moves horizontally rather than by travelling up walls. Most penetrating damp is caused by structural problems in a building, such as damaged or leaking guttering, cracked or missing roof tiles, and damaged joints in brickwork (pointing). Some of these issues allow walls to be soaked regularly in rainwater or provide a gap or bridge, allowing water to travel through. It can also be caused by internal leaks, such as leaking pipes under the sink or bath. Unlike newer buildings, if you live in an older building with solid walls and no cavity, you’re more likely to get penetrating damp.

In order to identify what’s causing the penetrating damp you’ll need to work out what might be saturating your walls or ceilings with water, signs of leaks, cracks or defects are likely to be the culprit. Looking at where the damp patch is will give you a good indication of where to look first.
To help guide you, we have compiled a checklist below:

Penetrating Damp Checklist:


  • Check for missing or cracked tiles.
  • Is the chimney flashing sound? (where a roof meets the wall of a chimney) .
  • Is the soil stack flashing sound? (where the soil stack may be installed through the roof).
  • Check for missing roof ridge tiles? (The capping tiles across the top of your roof).
  • Is the flashing around any velux/roof windows sound.
  • Is the ridge pointing sound?
  • Is the pointing in roof valleys sound?
  • Check valley gutters are not blocked with debris.

Gutters and Downpipes

  • Check for blockages in the gutter.
  • Make sure the downpipes are not blocked and running free.
  • Look for damaged guttering including brackets and joints
  • Look for missing guttering
  • Are any gutter joints leaking?
  • Make sure water can’t channel behind your guttering. (if your roof does not protrude the gutter enough and/or felt/eves boards are not present).
  • Make sure water can’t bypass the gutter. (if your roof protrudes the roof too much, gutter is installed too low).
  • Check ‘hoppers’ are running free. (In some installations, hoppers accept waste water from sinks, baths, and showers).
  • Check rainwater floor drains and gullies for blockages.

Doors & Windows

  • Check the Window and door sills have a ‘drip groove’ (which should stop water traveling under the sill and hitting the wall).
  • Check the window/door seals are not split, cracked or missing. (the sealant around the window and door frames).


  • Check for cracks in the brick joints. (commonly known as pointing).
  • Look for missing pointing
  • Ensure cables have drip loops, to prevent water following the cable into the property.
  • Check for holes around cables that go into your house i.e. aerial, phone line, sky satellite cable.
  • Check for holes around pipes coming out of you home i.e sink, bath and shower pipes, toilet soil pipe and outdoor tap, gas pipe etc…
  • Check flashing on connected conservatories, extensions and garages.


  • Check the waste pipes for leaks on sinks, baths, and showers.
  • Check for leaks on water pipes feeding toilet cisterns, sinks, baths, and showers.
  • Check radiator pipes for leaks.
  • Check tile grout is sound inside showers.
  • Check bathtubs, sinks and showers are sealed in properly, with no cracks or splits.

Fixing the issues

It’s simply a case of fixing the issues you identify during your inspection. Clean out gutters, unblock downpipes, fill holes, reseal, repoint, fix leaking pipes and replace cracked or missing roof tiles etc… It may be better to leave some of these tasks to a professional, but if you have the confidence, you can fix a lot of problems yourself.

Should you require assistance please call one of our friendly team on 0845 604 1288If you are looking for a qualified builder to help with your damp issues please visit Protech Damp Solutions.

Penetrating Damp

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