Mould in the Home: Why It Happens, How to Fix It Properly, and What the Law Now Requires

Mould is something almost every homeowner or tenant will encounter at some point. It’s often dismissed as a cosmetic nuisance – something to wipe away or paint over – but mould is a symptom of other problems and, in some cases, a serious health risk.

Here we are talking about:

• What mould actually is and why it appears
• Why painting over mould in the home doesn’t work
• How to fix mould properly, step by step
• The role of specialist products
• What social landlords in England must do under Awaab’s Law
• Practical advice for both tenants and landlords

What Is Mould – and Why Does It Happen?

Mould is a type of fungus. It thrives in environments where moisture, warmth, and nutrients are present, which makes homes an ideal breeding ground when something goes wrong.

While mould is certainly unsightly, it’s not just an aesthetic issue. Prolonged exposure can contribute to respiratory problems, allergies, and asthma, particularly in children, older people, and those with existing health conditions.

Common causes of mould include:

• Condensation on cold surfaces
• Plumbing or roof leaks
• Poor or inadequate ventilation
• Cold walls caused by poor insulation
• Rising damp

Activities such as drying laundry indoors can add moisture to the air. However, damp and mould should not simply be blamed on residents: leaks, inadequate ventilation, insulation and other building defects need to be investigated.

Prevention vs. Painting: Why Covering Mould Doesn’t Work

Painting over mould without addressing the cause is one of the most common and costly mistakes.

Paint does not fix the source of moisture. Covering the affected area may hide staining temporarily, but it does not resolve the conditions allowing mould to grow.

What actually helps prevent mould long term?

• Identifying and addressing leaks, damp and condensation
• Improving ventilation where necessary
• Addressing insulation problems and cold surfaces

Without addressing the underlying cause, mould can return, no matter how many coats of paint you apply.

A Proper Mould Fix: Step by Step

Fixing mould properly needs a suitable approach to both the moisture problem and the affected surfaces. Extensive, recurring or hidden mould may require professional assessment and treatment.

Step 1: Find the cause

Is it condensation, a leak, or rising damp? Investigate the source of moisture rather than treating the visible staining alone.

Step 2: Fix the cause

Repair leaks, improve ventilation, or address insulation gaps as appropriate.

Step 3: Clean and treat the mould

Use a suitable mould treatment, following its instructions for application, protective equipment, ventilation and any rinsing requirements. Never mix cleaning products.

Step 4: Prepare and protect

Once the underlying problem has been addressed and the surface has been treated and allowed to dry, prepare and finish it with a suitable coating system.

The Role of Specialist Paints

Mould-resistant paints can help protect the paint film once the underlying moisture problem has been addressed. They are not a substitute for repairs or mould removal.

Here’s a step-by-step approach to using a paint system:

1. Clean and prepare the surface
   Follow the chosen coating system’s preparation instructions. Zinsser Universal Degreaser and Cleaner is used to remove dirt, grease and other contaminants; it should not be confused with a dedicated mould treatment.
2. Treat mould growth
   Use a dedicated product such as Zinsser Mould Killer and Remover, following the manufacturer’s instructions. A general household cleaner should not be assumed to provide the same treatment.
3. Prime and block remaining stains where required
   Once the surface is treated and dry, use a suitable stain-blocking primer where the coating system requires one. Options include Zinsser B-I-N and Zinsser B-I-N Aqua. Check suitability for the surface and follow the specified drying and recoating times.
4. Apply mould-resistant paint
   Finish with a suitable mould-resistant product such as Zinsser Perma-White, which protects its paint film against mould and mildew growth. Despite its name, it is available in a range of tinted colours as well as white. Check the available colours and finishes before ordering.
   
   Another option to consider is Ronseal 6 Year Anti Mould Paint. Follow the individual product’s preparation and application instructions.

Wood Finishes Direct stock a range of specialist mould treatments. Zinsser Perma-White is available in a range of tinted colours, not just white!

Do you really need to clean before painting?

Yes. Treat existing mould and prepare the surface according to the manufacturer’s instructions before painting. Applying paint alone does not remove mould or resolve the moisture problem.

Awaab’s Law: What Social Landlords in England Need to Know

Awaab’s Law came into force for social housing in England on 27 October 2025, following the death of two-year-old Awaab Ishak.

The deadlines below concern social landlords, including councils and housing associations. They should not be presented as deadlines applying automatically to every private landlord.

What does the law require?

• Investigate potential significant damp and mould hazards within 10 working days of becoming aware of them.
• Where a significant hazard is confirmed, complete the relevant work to make the home safe within 5 working days of the investigation concluding.
• Investigate potential emergency hazards and complete any necessary work to make them safe within 24 hours of becoming aware of them.
• Normally provide a written summary within 3 working days of the investigation concluding.
• Arrange suitable alternative accommodation at the landlord’s expense if the home cannot be made safe within the required deadline.

Making the home safe may involve temporary measures. Further work to prevent the hazard recurring is subject to additional requirements; the five-working-day safety deadline does not necessarily mean every permanent repair must be finished within that period.

For full details, see the government guidance for social landlords.

Common Myths and Mistakes

Some of the most frequent issues professionals see include:

• Painting over mould without fixing moisture problems
• Ignoring ventilation and insulation problems
• Blaming tenants for issues with the building

Are there any temporary fixes?

Appropriate ventilation, a dehumidifier and allowing air to circulate around furniture may help manage moisture while repairs are arranged. These measures do not replace investigating and fixing the underlying cause.

Practical Advice: Tenants and Landlords

If you’re a tenant:

• Report damp and mould promptly and keep a written record.
• Keep records and photos.
• Explain any health concerns or circumstances that could make the problem more urgent.
• If you are a social housing tenant and your landlord fails to act, use its complaints procedure. You can also seek help from the Housing Ombudsman or obtain independent housing advice.
• If you rent privately, seek advice about the duties and complaint routes that apply to your tenancy rather than assuming the social housing deadlines apply.

If you’re a landlord:

• Treat all mould reports seriously.
• Investigate moisture sources, not just surface damage.
• Act quickly, communicate clearly, and document everything.
• Consider proactive inspections, especially in bathrooms, kitchens, and older properties.

Final Thoughts

Mould isn’t just something to paint over – it’s a warning sign.

The right approach is:

1. Find the cause.
2. Fix the cause.
3. Clean and treat the mould appropriately.
4. Use specialist products correctly where needed.

Good landlords who maintain safe, healthy homes deserve credit – and clear rules now help protect tenants from dangerous living conditions.

For More Help & Advice

For help choosing mould treatments and paints, call our experts on 01303 477544.