What causes damp patches on ceilings

What causes damp patches on ceilings

By Ruth MacEachern

Product Manager

Damp patches are caused when moisture is able to accumulate below the surface in materials throughout your home.  The most common cause of this type of damp is condensation, although leaks in pipes or gaps in your roof can also cause moisture to soak into walls and ceilings.

Understanding the cause of a damp patch on your ceiling is the first stage in preventing it getting worse, and leading to damage to the material, or creating an environment where mould or mildew can form.

What does a damp patch look like?

In most cases, the most obvious sign that you have a damp area on your ceiling is that the paint has discoloured to create a “tidemark” around the area.  This can be an important indicator of the source of the damp.

In cases where the patch has a brown or darker tone, it is likely that the damp has been caused by water soaking through from above and bringing dust or colouring from the underlying plaster with it.  When water is soaking through from the other side of the ceiling board, it is often linked to a leaking pipe.  This might be a poor seal on the outflow from a bath or sink in the room above, or water leaking through from a radiator that has been jolted.

If the damp patch does not have a brown colour to it, it usually means that the damp is soaking through from the surface you are facing.  That can be a sign that the damp is being caused by condensation forming in that area in the room itself.

Dealing with Damp

Once you understand the cause of a particular damp patch, you can start to treat it and address the problem.  A leaking pipe, or a hole in your roof that is letting in water will usually require a plumber to visit, or a builder to make some repairs.  Once that is complete, the damp problem in that area should be resolved, and you can re-decorate the affected area once it is fully dried out.

If condensation is the cause of your ceiling damp patch, you should consider what the source of condensation might be.

In wet rooms such as kitchens or bathrooms, the source of the condensation will usually be the activities in that room.  In kitchens, you should ensure that extractor fans are used when cooking and that pan lids are used to reduce the amount of moisture that is released into the air.  The same is true in bathrooms – keeping your extractor fans running for 30 minutes after a bath prevents condensation from having a chance to form, and also stops moisture “leaking” out into the rest of your home where it may form condensation on cool walls in other rooms.

If you already have extractor fans in wet rooms and are still facing problems with condensation damp in other rooms, it is possible that those fans are no longer running efficiently.  Over time, older fans with filters may become clogged with dust and grease so that they become unable to move air properly.  This gives moisture more time to settle.

Speaking to a ventilation specialist to find out whether your current ventilation system is sufficient for your needs is a good idea, as they will be able to identify the source of your problem.

In cases where damp patches are forming from condensation away from your kitchen and bathroom, the cause is often inadequate air flow around your home.  The moisture that causes the condensation and damp is often still originating from bathing and cooking and escaping into other rooms, but insufficient air movement means that the air has a chance to come into contact with cooler surfaces.

A whole house ventilation system may be suitable in these cases.  PIV and MEV solutions move air around a house more consistently which means that condensation has fewer opportunities to form. 

Contact us today to find out what solution will help you to address damp problems on your ceilings and prevent them from developing into mould that can be damaging to your health.