Blocking Water Stains - How to Stop Water Marks Discolouring Your Ceiling

Summary: How to stop stains coming through emulsion and how to block damp stains. Water marks that can discolour a ceiling are remarkably persistent so you will need to take a little time to make sure that they are gone for good. Find out our technique to stop damp stains on your ceiling here.

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If you have ever had a leak come through a painted ceiling or an old wall has been damp in the past, you will know that it does not matter how many coats of emulsion, or how many layers of wallpaper you put on, the stain will still come through.

Not only is it really ugly it is one of those things that will seriously put off a potential buyer, or even a prospective tenant.

Causes of Water Stains on Ceilings and Walls

Water stains on walls and ceilings can be the symptom of a much larger problem and this is something that you should look into immediately.

Finding and fixing the cause of the water stain and associated damp must be your first priority. Check for leaking radiators, leaks in the roof or leaks in bathroom pipe-work or wastes - our finding water leaks project can help you with this.

Water stain in ceiling from old or current leak

A water stain is the sign of an old or current leak

Stopping Water Marks and Stains

Stopping a damp stain or water mark on a ceiling can be very difficult.

The only way to stop the water mark discolouring the paint is to cover the stain with a stain blocker or an oil based paint first. You can then emulsion or paper overit.

If you don't create this barrier the water mark will just keep on coming through, however many coats of emulsion you put on!

You can make a stain blocker by mixing some oil based undercoat and gloss together and painting this over the stain first - we suggest that roughly a 50/50 mix is about right, although if you don't do this exactly it will not matter.

Proprietary stain blockers can be bought by clicking through to our tool store below or searching the store.

Water stain in ceiling from old or current leak

Water marks can be stopped with a suitable stain blocker

A ceiling may have leaked in the past, the leak been fixed and the ceiling may even have been plastered over...... Those old water stains will keep coming through until and oil based coat is applied first.

How Stop Stains Coming Through Emulsion Paint

Here's out step-by-step guide to stopping water and damp marks showing on your ceiling:

  • Find and fix the cause of the water mark: This can be tricky, but there's absolutely no point trying to deal with the water stained paint until you have done this. Make sure that the ceiling (or other surface) is completely dry
  • Prepare the ceiling for painting: Often the surface will have become damaged and so you will need to patch any cracks and gaps with filler. If the plaster has blown, you might need to re-plaster - See here for more information
  • Apply the barrier to stop the water mark: Whether you use your own or a product specifically purchased for the job you will need to use this to stop the water mark coming through the emulsion
  • Paint your ceiling (or stained surface): You can now paint over the area that was stained and be confident that the water mark will not return

You might end up having to paint the whole ceiling as the old paint might have become discoloured over time and to get an even colour across the whole surface, the only thing to do is to paint the whole thing.

Don't fancy doing this project yourself? We work with Checkatrade to ensure that we recommend only reliable and trustworthy tradesmen.

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