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
Katie Warren
Jan 27, 2026
Second to none. From all our questions about the process (which were answered swiftly, leaving us in no doubt), to installation (the engineer was friendly, professional, worked fast, and left zero mess), we were impressed. We weren't expecting to see a difference so quickly, but since the very first day we haven't had a single drop of condensation, and the air in our house feels fresh. We can't recommend these guys enough, and we have been recommending them to everyone!
Lee Pinner
Jan 26, 2026
Would highly recommend. We had a PIV fitted to help with condensation in the house. Steven was very helpful and knowledgeable. Jonny was great when fitting the PIV. Quick, no mess and answered any questions we had.
Babatunde Ojomo
Jan 26, 2026
I highly appreciate the services we got from Clear air PIV installations. The communication and advise provided from start to finish was very pleasant. Happy I have installed a PIV system and am seeing the benefit. Thanks to the team.
B U
Jan 25, 2026
From the beginning Clear Air PIV were really helpful and clear in explaining what needed to be done talked through everything before starting any actual work. The installation itself was very clean and the electrician was extremely friendly. Overall I am happy and I would not hesitate to recommend them to anyone.
Darren “01dardon01” Jutson
Jan 10, 2026
This was a great service right from the initial phone call. The communication was there all the way through and the knowledge of the install and product was obvious from the start. They asked key questions about the house to ensure that this product could be installed, and when the work was carried out it was done quickly, cleanly and when they said it would. No fuss and no issues. The product is also good. It's quiet and it works. I would definitely recommend ClearAIR PIV to anyone.
Phil Coe
Jan 9, 2026
Fully recommend, service and communication was excellent. Implementation spotless and we are getting no condensation, even in the coldest months.
Helen Leonardi
Dec 11, 2025
Would highly recommend!! Fast and professional installation, competitively priced. The PIV is working well.... should have had it done ages ago!! Well worth the outlay
Rob Gifford
Nov 28, 2025
Had a piv system installed by clearAir Piv. Brilliant company to deal with. They were clean and tidy. A pleasure to deal with and would recommend to anyone. Hopefully this system solves our condensation problems.
Katrina Barlow
Nov 13, 2025
From initial enquiry to competion of fitting of VIP unit I have nothing but praise for this firm. Communication from Steven was always prompt and information given was clear and concise. No "hard sell" just good advice. Cameron fitted the unit and completed full electrical check. He was also very pleasant, got on with the job and was able to answer any queries. He also left no mess and completed the work in a few hours. Early days but the unit appears to be doing its job well. Absolutely no condensation from day one. Can completely recommend this firm.
Luke Pollard
Nov 1, 2025
Highly recommend. Fantastic team
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 Grimwood
Oct 28, 2025
Brilliant from start to finish. We couldn’t be happier with the professionalism showed by Steve and his team and would definitely recommend to anyone looking to get a PIV system installed.
Ashley Roe
Oct 17, 2025
I’ve just had installed a piv system. Steven and his team were a delight to deal with. Professional from start to finish. All our mould we were so worried about previously has now disappeared. Thanks again.
Mark Ford
Oct 4, 2025
Knowledgeable, easy to deal with, very happy with the results. Would definitely recommend!
Lauren Barker
Oct 3, 2025
I recently had a new PIV unit installed by ClearAIR and the experience was excellent from start to finish. Steven and his team were professional, efficient, and a pleasure to deal with throughout the entire process. Since the installation, our mould problems have completely resolved and the improvement in air quality has been remarkable. ClearAIR delivered outstanding service and results, and I would not hesitate to recommend them.
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.
Leigh Merry
Oct 2, 2025
Nick Paulson
Oct 2, 2025
Fantastic service came on time well early even re solved a problem we have had for years removing our damp highly recommend steven at clear air
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.
Albert Carroll
Sep 27, 2025
Wasn’t sure what I needed, and Steven recommended a product that has transformed the condensation in our house. 100% recommend
Ellen Carroll
Sep 27, 2025
Really great service from Steven and the team. Couldn’t recommend more highly
Danielle Lanae
Sep 24, 2025
We had a PIV unit installed in one of our rental properties. The team were very helpful and the price was really good!
Tyler Ball
Sep 24, 2025
Had a PIV unit installed from these and I am really happy with the service and the price was really good
Leigh Drummond
Sep 5, 2025
Very impressed with Steven and his team. From the get go of filling out the questionnaire online, Steven contacted me and booked me in for a visit. He was polite and there was no pushy sales pitch, just straight talking and down to earth. I’d recommend anyone who’s considering having a PIV unit to contact Steven.
Adam Wilson
Sep 5, 2025
I Had a PIV unit installed and was very happy with the service.
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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.