When yellow mould appears on your walls, you need to say goodbye to it as soon as possible. Like all moulds, it spoils the aesthetic of your walls and, more seriously, is harmful to your health.
Yellow mould typically indicates an underlying issue that needs to be identified and addressed. If it's small areas, you can tackle removing mould from walls and surrounding areas yourself with some DIY or specialist solutions. If the problem is widespread, it might be time to call in the professionals.
Lee Keet started as a hands-on cleaning technician and built a leading cleaning services business. Gaining hands-on knowledge and training in a range of cleaning aspects, from eco-friendly products to best practices.
What is yellow mould on walls?
Moulds come in various colours, depending on the type of mould. Yellow mould can be a fuzzy-looking mould known as Penicillium. But this isn’t the only type, as Lee Keet, Managing Director of Vapor Clean Ltd explains, “Yellow mould is a term used for several mould species that produce a yellow appearance as they grow. The colour comes from the spores and the surface they feed on rather than the mould type itself.”
He adds, “It thrives in areas with high moisture, limited ventilation, and organic material it can break down.”
Yellow mould appears in many of the same places as other mould. Keet shares its common locations: “It typically appears on damp wood, wallpaper adhesives, insulation, food items, soil in plant pots, and around bathrooms or kitchens where condensation is common.” He adds, “It can also show up in loft spaces or under flooring if there is a hidden moisture problem.”
Signs of yellow mould
There will be obvious signs of yellow mould on surfaces as it grows, including mould on skirting boards. But, like most moulds, it doesn’t always appear in easy-to-spot locations.
A musty smell in the home may indicate the presence of yellow mould. Yellow mould thrives in warm, humid areas and grows quickly in high-moisture environments.
This will typically be behind furniture at floor level, where there’s poor airflow and rising damp due to a failure in the damp proofing. Yellow mould in other areas can be caused by penetrating damp where there’s defective pointing, cracked render or a faulty roof.
Try these to help remove mould from walls
A quick, simple-to-use mould spray that delivers the solution directly to the problem. Aims to remove mould from most hard surfaces, but is not ideal for porous surfaces such as wood.
A mould removal and prevention kit that features a fast-acting mould remover and a mould sanitiser. Includes a Microfibre cloth and a pair of protective rubber gloves.
When dealing with mould, you don’t want to breathe in the spores when disturbed. Use these FFP2 face masks with a pair of rubber gloves for protection.
Is yellow mould harmful?
This will depend on what type of yellow mould you are dealing with. Barrie Francis, a training manager at Timberwise, shares, “Yellow mould is most commonly part of the Aspergillus mould family” He adds, “There are several hundred known species of Aspergillus, with estimates ranging from around 200 to over 800 recognised combinations, though only a few dozen are known to cause human disease.”
While yellow mould is not toxic, it contains toxins that can exacerbate health problems – commonly respiratory problems – and is best avoided. Francis notes potential problems: “People with pre-existing respiratory conditions like COPD or asthma may experience worsened reactions from breathing in yellow mould spores, including coughing, wheezing, sinus irritation, headaches, or skin irritation.”
If you see yellow mould developing, do not touch it; remove it as soon as possible, especially if it is growing in an area where you spend a lot of time – i.e., the bedroom, lounge, or living room.
Barrie Francis works for Timberwise, a leading UK property care company specialising in damp, timber treatment, and waterproofing, where he serves as the Director of Training. Timberwise offers surveys (damp & timber reports) and treatments for issues like woodworm, dry rot, and rising damp.
Is yellow mould worse than black mould?
The colour of the mould in your home can indicate the type of mould, but to be sure, you will need to have it tested. Is it worse than black mould on silicone sealant? Unlikely. Keet says, “It’s not worse than black mould, but that’s not to say yellow mould is harmless.”
He adds, “Black mould is the most toxic and can cause serious respiratory problems, particularly for children, the elderly, and anyone with existing health conditions.”
Black mould, commonly found in homes, can cause the same issues as yellow mould. However, black mould has an element that produces neurotoxic compounds which can affect the brain, with children and those with poor immune systems particularly vulnerable.
All moulds typically contain some form of toxin, and the obvious thing to do is get the problem sorted as soon as possible.
How to get rid of yellow mould on walls
If you find mould in your home, remove it quickly to prevent further spread. Francis recommends: “For small infestations, use a non-toxic fungicide while wearing appropriate personal protective equipment such as gloves and a mask.” However, if you have a more serious issue he recommends calling a professional, “For larger infestations or recurring growth, consider professional mould remediation and address the underlying moisture source to prevent regrowth.
Before you start dealing with mould on your walls, you want to get yourself some protective gear to help you avoid inhaling spores. Keet says, “PPE is important if you're removing it yourself because disturbing mould releases spores. At minimum, you should use gloves, a mask, and eye protection, and improve airflow while you work.”
He adds, “Small areas can be cleaned using specialist mould removal products or a detergent solution followed by a disinfectant.” Alternatively, use products you already have at home.
Start with a mixture of warm water and a few squirts of washing-up liquid and use a clean cloth or kitchen sponge to wipe off the surface mould. Now get a few sheets of kitchen roll and wipe the surface clean and dry. Repeat the process, but ensure you use a clean cloth/sponge, clean water, and new kitchen roll.
Keet warns, “Avoid using bleach on porous surfaces because it can drive moisture deeper and cause regrowth.”
How to tackle yellow mould that comes back
If you spot yellow mould reappearing in areas you have cleaned and treated, you likely have an underlying issue that needs to be addressed. You may have rising or penetrating damp in the walls, which is causing the problem. If the cause of the issue isn’t dealt with, the mould will keep reappearing.
If you are unsure about the cause of the mould, you can call in a mould removal and treatment specialist to help identify the problem.
If the reappearing mould is in your carpet or on wood such as doors, door frames, or skirting boards, the best option is to replace the affected areas to prevent it from recurring. Mould on windows is another common problem that is typically different from yellow mould but still needs to be addressed.
Can you paint over yellow mould?
Yes, you can paint over once you have cleaned and dried the affected area. Painting over mould without treating the affected area will simply see the mould reappear at some point in the future.
Once the area is clean and dry, remove any flaking paint. Use a scraper and a fine-grade sandpaper to prepare the surface. Once the surface is ready, apply a mould-resistant paint such as Zinsser Perma-White Self-Priming Interior Paint from Amazon before applying the final coats.
Mould is unsightly, and once you have removed it, it is a good time to repaint and hide any marks left behind. Check out our guides on painting skirting boards and painting skirting boards with carpet. If you need to redecorate, check out our decorating mistakes to avoid and ensure a good finish.
