Black Mould Season 25/26 Has Begun
Author
Ian Murray
Date Published
Every year, as temperatures drop and homes are sealed up against the cold, the same problem returns. Black mould season is back for 2025/26. Thousands of UK households will already be noticing the first signs. With black mould appearing on walls, ceilings, and window frames.
Condensation builds up quickly once heating goes on and windows stay shut. Without enough ventilation, excess moisture has nowhere to go.
Cleaning products are simply not enough. The result? Damp corners, musty smells, and spreading mould problems.
All of which is unpleasant and harmful to your health. Especially those with weakened immune systems.
For landlords and homeowners alike, the time to act is now! Before black mould takes hold causing health risks and long lasting property damage.
Why Black Mould Appears in Autumn and Winter
Black mould thrives in damp air. During the colder months warm indoor air meets cold surfaces like external walls and window panes. This creates condensation, which is the perfect environment for mould to grow.
Even homes that appear clean and well-kept can suffer from black mould. This is because windows are kept closed most of the time in Winter. Bathrooms and kitchens have poor ventilation and that air also gets trapped. Furniture is placed tightly against cold walls and often next to radiators and people use their tumble dryers.
Left untreated, black mould can damage plaster, wallpaper, paintwork and timber. More worryingly, it can trigger respiratory issues like allergic reactions, skin rashes and asthma. This can be especially serious for children and older people.
Effective Black Mould Treatment
When black mould appears, cleaning it off is only a short-term fix. The key to a lasting black mould treatment is removing the root cause. Which is excessive humidity and poor air circulation.
Professional mould removal products can help kill spores, but if condensation continues, it will come back. The only reliable way to stop it is to improve airflow.
That’s where a Positive Input Ventilation (PIV) system from ClearAIR PIV can make all the difference.
How a PIV Unit Stops Black Mould
A PIV system works by introducing filtered, fresh air into your property. No need to open windows in the cold UK Winter. Its all done at a gentle and continuous rate via the PIV unit. This replaces stale, moisture-laden air with clean, dry air from outside.
By maintaining positive air pressure, a PIV unit prevents condensation from forming on cold surfaces. This removes the conditions mould needs to grow.
Key benefits for landlords and homeowners:
- Stops black mould before it starts.
- Reduces humidity throughout the property.
- Protects walls, ceilings, and fixtures from damage.
- Improves indoor air quality and helps reduce odours.
- Low running costs and minimal maintenance.
Once installed, a PIV unit quietly does its job 24 hours a day, keeping your property fresh, dry, and free from damp.
To learn more about how this works, visit our Black Mould Treatment page for full details.
Why Act Now
October to March is the peak black mould season in the UK. By the time visible mould appears, the underlying moisture levels are already high.
Installing a PIV system before winter fully sets in will help you stay ahead of the problem. It will help you to avoid costly repairs and complaints later in the season.
For landlords, this is especially important under new compliance standards like Awaab’s Law. This will require swift action on damp and mould issues from October 2025. Preventing mould now is the easiest way to stay compliant.
Get Help From A Local And Recommended Specialist
Hannah B-C
Nov 1, 2025
The service that we received from ClearAir PIV and Steven himself has been excellent. We have been looking into PIV systems for a while as we have had such a problem with condensation on our bedroom windows. As soon as the temperature begins to drop each year the windows are covered. It has ruined the decor around the windows and caused mould to grow on the frames. Having spoken to Steven on the phone I could tell had specialist knowledge in the area. There was no hard sell, just advice. I got him booked in the same week to fit an Nuaire PIV and I’m so glad we did. Fitting was done quickly and cleanly by John who was friendly, well presented and very knowledgeable and experience in ventilation systems. Steven came too to give advice on another issue we had discussed on the phone. Result: NO MORE CONDENSATION!!! I thought it might take a few days to clear the moisture, but the next morning we checked the windows when they would normally be soaked and… nothing! And nothing since! So happy! I’d read in some reviews of the PIV systems that they were noisy and made the landing cold. This is not my experience. I honestly can’t hear it and although the landing may be ever so slightly cooler, the overall temp of the house isn’t effected and it’s not anything I’m concerned about.
Jack Capstick
Oct 2, 2025
Just had a new PIV unit installed by ClearAIR and I can only say positive things. The whole team from Steven to his employees were amazing to work with, since the instalment all our mould has disappeared and I can’t thank the team enough.I highly recommend ClearAIR as they were worth every penny.
Sarah Cocking
Oct 2, 2025
Would highly appreciated Steven at clear air piv. From start to finish he was so helpful and kept us upto date with the installation. We've noticed a massive difference since. Thank you for a great service
Sarah Brent
Oct 2, 2025
Excellent Service and Results! I recently had a new PIV system installed in my home, and I couldn't be happier with the outcome. Communication with Steven was excellent from start to finish — he responded immediately to any queries and kept me informed throughout the entire process. The installation itself was smooth and professional. Since having the system installed, I’ve had no issues with mould or condensation — a huge improvement! I would highly recommend Steven and his company, CLEARAIR PIV Ltd. Reliable, efficient, and effective service.
Lois Green
Oct 2, 2025
Couldn’t recommend Steven enough. From start to finish the communication was amazing and everything was explained so clearly. He was professional, efficient, and made the whole process completely stress-free. The quality of work is outstanding, and it’s clear he really takes pride in what he does. I wouldn’t hesitate to recommend Steven at Clear Air PIV to anyone looking for a reliable and trustworthy service.
Is PIV the right solution for you?
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FAQ's About Black Mould Treatments
Here are some of the most frequently asked questions we get about our black mould treatments across the UK.