How to Get Rid of Mould on Walls Permanently

Updated Jul 1, 2024 | Posted Jul 29, 2022 | Product Advice | 1 comment

As a professional decorator, tackling mould is something I have had to do on many occasions. A lot of people wrongly assume you can just paint over mould. It may cover it for a certain amount of time but won’t deal with the problem in the long term.

In this blog, I’m going to explain how to get rid of mould on walls permanently. I’ll start by explaining what mould is and what causes it. Then I’ll go onto killing the spores, painting an affected area, then how to prevent it from coming back. I hope you find it useful.

 

What is Mould and What Causes it?

 

Quite simply, mould is caused by the growth of a certain fungi in your home. What you see on your wall is the formation of spores. These spores are dust-like and can become airborne, which then seeds more patches of fungi in other parts of your room or home.

Conditions need to be right for mould to grow. You normally find it in rooms that are very humid or have issues with excess moisture. Possibly from damp coming in from the outside of your home, but sometimes from a leaking pipe or similar. Condensation is the main cause of mould growth.

The most common places to find mould are bathrooms and kitchens because of the excess steam, which normally condenses on the coolest wall / window and keeps it wet for long periods.

As a decorator, I tend to come up against walls full of mould when working for landlords. This might be for a few reasons, including properties being empty for weeks or months at a time, poor ventilation, people drying their clothes inside the house, or cheap paint being used to decorate.

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What Issues Are Caused by Mould on Walls?

 

Mould isn’t exactly pleasant to look at, and I’ve already touched on the possibility of mould spreading to other areas of your home. It affects air quality too. If you have mould patches on your walls in a room, then you can guarantee some spores are already airborne.

This is a particular problem for people with asthma as the spores can trigger an attack. I know this first hand because I used to suffer quite badly. It also affects people with other breathing difficulties, including chesty coughs. Allergies like hay fever can also be triggered by mould spores, so stuffy noses and sneezing can be common in homes with mould.

 

How to Get Rid of Mould on Walls Permanently

 

Right, now you know what mould is and the issues associated with it, let’s get down to the good stuff!! How to get rid of mould permanently. Do not fall into the trap of thinking you can just paint over it!!

I’ll quickly run through the steps you should take and the materials you’ll need. Then I’ll go into a little bit more detail and recommend products etc. I’ll include links so you can buy the products, but you can get all this stuff from any good trade decorating centre.

 

Supplies

PPE – Gloves, long sleeve shirt etc.

Fungicidal Wash – Click here to see online prices.

Bucket

Cloth

Stain block – Click here to see online prices.

Antimould paint – Click here to see online prices.

 

Tools

Paint brush – Click here to see online prices.

A good quality paint roller – Click here to see online prices.

 

Steps

 

Wear PPE

You should wear some sort of protective clothing (PPE) when tackling mould, as the spores can irritate your skin. Rubber gloves, a long-sleeve top and a mask will help protect your health while you work. Pop all your clothes in the wash once you’ve finished treating the mould.

 

Ventilate

A lot of the time, mould growth is caused by bad ventilation. If you’re working in a kitchen or bathroom, you may need to install an extraction fan or air brick. A dehumidifier would also help (although not ideal). Paint might get rid of the mould, but solving the root cause is always preferable.

 

Kill Mould Spores

The first thing you need to do is kill the spores. Otherwise, it’ll just come back anyway. Zinsser do a brilliant mould killer which you can buy online by clicking here. This is perfect because you can just spray it on, leave it for 10 minutes, and then wipe it off. Click here to learn more.

If you don’t want to buy a specialist product, then you can use a diluted bleach solution. Bleach will not penetrate a porous surface (like your walls). There are a couple of issues with using bleach to kill mould. Yes, it kills the spores on the surface, but it won’t kill any mould which has embedded itself into the wall. In fact, you’re feeding it in a sense by wetting the walls, which can cause mould to spread. Bleach can be useful for washing mould off a non-porous surface, but it isn’t a permanent solution.

 

Block the Stain

Once your walls are clean and the mould has been killed, you will need to block the stain. Surfaces should be clean before you do this.

 

Repaint with an Antimould Paint

Some paints are formulated with extra biocide, meaning they will withstand mould growth. Using one of these products means a more permanent solution to mould.

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Blocking the Stains Caused by Mould

 

If you don’t paint your walls, the mould may come back unfortunately. Before decorating your room, you will need to block the stains caused by the mould. There are several products you can use for this. You only need to block stains in the affected areas.

The cheapest way to block a mould stain is to use oil-based undercoat. Just be aware that applying an oil-based product in an enclosed space will cause unpleasant fumes, so open a window and continue to wear a mask.

If you do use undercoat, you should leave it at least 16 hours to dry before you apply a water-based paint over the top.

Zinsser Cover Stain is another great product for this and will not take as long to cure before you can paint over it. It’s easier to use too.

zinsser cover stain is a good primer for covering mould

Decorating Your Room so Mould Does Not Come Back

 

Right, so we know what mould is, we’ve killed the spores and we’ve blocked the stain. The point of this blog is to explain how to get rid of mould on walls permanently, so there is more we need to consider. That includes paint.

Cheap retail matt emulsion, or contract matt does not contain much in the way of polymer binder, so remains porous. This is a major issue in the fight against mould because it will hold onto water and create the perfect habitat for this fungus.

You could opt to use a good quality trade eggshell. Although there is nothing in the paint to kill spores as they land, the product itself dries waterproof. Condensation will just run off the walls and help keep them dry.

There are other products you can use which will actively kill any mould spores in the room and stop it from coming back. Zinsser Perma White is the perfect example of this. Dulux make a product called Mould Shield which is worth having a look at. Or, if your issue is with condensation, then maybe even an insulating paint like SureTherm!

You have plenty to look at. I can personally vouch for Zinsser Perma White. It is available online in any colour, it dries durable, and mould will never grow on your walls again. The opacity in white isn’t very good, so expect to need an extra coat. You can even use Zinsser Perma White on your woodwork.

I used this paint in the changing room of a swimming pool about 8 years ago. Before I decorated it, the owner had to hire someone to paint it every year because mould would grow rampantly on the walls. 8 years after I painted it with Perma White, it still looks brand-new!

Zinsser Perma-White will stop mould from coming back

Preventing Moisture Build-Up

 

If you really want to get rid of mould on walls permanently, then you will need to do what you can to prevent condensation in your rooms. I mentioned in one of the opening paragraphs that condensation is the main cause of mould, and I stand by that.

Simple things like regularly opening a window and not drying wet clothes inside will help, but you may need to do more. An extraction fan in your bathroom or kitchen will almost certainly make a difference. In fact, an extraction fan may be the silver bullet needed to prevent mould from coming back.

A vent will also help and will not cost as much as an extraction fan. Anything to bring fresh air in and allow moist air to leave.

Sometimes the placement of radiators play a big part too. Ever wondered why more times than not, you’ll find a radiator on an exterior wall, or under a bay window? It’s because this is the coldest wall in your room, so most prone to condensation when you put your heating on. Having your radiator on the coldest wall will stop this.

A dehumidifier is a fantastic short-term solution. These handy little gadgets suck air in and run it over a cold metal radiator. Moisture in the air condenses on the radiator and is collected, so the air that comes out is a lot dryer. The only issues with dehumidifiers are they’re bulky and loud, so they’re not really a practical solution.

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If your mould is caused by damp coming into your home from the outside, then you should ask a builder to help you diagnose the problem. It may be a simple fix like cleaning your gutters or changing the sealant around a window. It may be something a bit more sinister like rising damp due to a failed membrane.

 

Final Thoughts

 

Sorry if I’ve gone on a little bit. I just wanted to touch on everything you should look at when working out how to get rid of mould on your walls permanently. Follow the steps outlined in this blog and you should solve the issue. I hope it helps.

There’s a quick video below of a fix I carried out for a client. It was just a quick touch-up job because my client didn’t want to go through the ordeal of decorating the whole room.

We treated the mould with GK Mould and Mildew Cleaner, blocked the stain using a shellac-based spray, mixed the paint with an anti-mould additive, and then touched up the affected area.

I’m confident on this occasion that there isn’t an underlying issue causing the mould. It’s just a mixture of poor ventilation, lack of heating during the winter, and clothes being dried inside. Therefore, using specialist paint products like this should be all that’s needed for a permanent fix.

A Quick Demo on Dealing With Mould

Mike Cupit explains the process of getting rid of mould in a client’s bedroom.

What do Other Decorators Think?

Four steps:

1) Solve the problem (i.e. make sure there’s adequate ventilation in the room etc).

2) Kill the mould by treating it with a suitable mould killer, e.g. Zinsser Mould Killer or Ronseal 3-in-1 Mould Killer.

3) Block the stain to prevent it bleeding through your paint – I find two coats of Zinsser BIN does the trick.

4) Paint with a mould resisting paint to help prevent the problem coming back – my favourites are Crown Clean Extreme Mould-Inhibiting Acrylic Eggshell (brilliant in bathrooms) or Zinsser Perma-White.

Robin Gofton

Professional Painter and Decorator

In the time I have been a decorator, I have found the best method of removing mould permanently is….

Check there is enough ventilation in the room. If there is, then proceed with killing the mould with Zinsser mould killer. Once dried, apply 2 coats of Zinsser BIN, then when this has dried slightly, sand down with 240 grit sandpaper. Then apply 3 coats of Zinsser perma-white (this can also be tinted to colours) stand back and admire the Job you have done

Pete Rigby

Professional Painter and Decorator

First of all, mould shouldn’t be ignored and just covered up! Clients should be informed that the mould is dangerous to your health and must be sorted properly.

George De Best

Professional Painter and Decorator

Wash with bleach, then a coat of oil-based undercoat. However, if you don’t find the cause of mould in the long-term, it’ll always eventually come back.

Simon Young

Professional Painter and Decorator

It really depends on the manifestation of the mould 0n the walls and the cause.

Ventilation is usually an easy target, but age of the substrate and maintenance regime can also play a part.

If you can’t solve the issue that is causing the mould, then it needs to be managed!

HG mould spray is good for this as it requires little more than spraying the area when you see mould occurring. This is a temporary fix and will surely need repeating in time.

The way new houses are built promotes mould growth (ask any site dec) and once it’s in its a complete pain to get out.

Not one to step into politics, but the heating crisis is going to compound this problem for poorer family’s.

Kim Burgess

Professional Painter and Decorator

Get a fan fitted as will stop excess steam from bath and shower.

Mark Straw

Professional Painter and Decorator

The first thing I would do is to recommend having a good quality extractor fan fitted. Then wash down with a fungicidal solution, then 3 coats of Zinsser perma white. This is the only way to get rid of mould on walls permanently.

Ian Carter

Professional Painter and Decorator

Updated Jul 1, 2024 | Posted Jul 29, 2022 | 1 comment

About the Author

About the Author

Mike Cupit has been in the decorating industry since 2002 and has mostly worked as a Trade Decorator in the domestic sector (peoples’ homes). Self-proclaimed “product geek”, Mike has a passion for paint and decorating tools. Mike now spends most of his time testing paint products and tools, comparing them to similar products on the market, and blogging about the industry in general.
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1 Comment

  1. Chris Ruffalo

    The article’s emphasis on using environmentally friendly and non-toxic methods to eliminate mould is commendable, as it promotes both the health of individuals and the well-being of the environment. Overall, this article serves as an invaluable resource for homeowners seeking effective and sustainable ways to permanently eradicate mould from their walls.

    Reply

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