Mould after grant funded insulation?

Mould after grant funded insulation?

8:36 AM, 11th April 2022, About 3 months ago 25

Text Size

Hi Everyone, I have a property owned for almost 3 decades. Recently I have had mould appearing on the inside wall below the front ground floor window.

Despite painting over with anti-mould paint the mould keeps reappearing. I have a suspicion that it is connected to the insulation which was done approx 10 years ago. I never had this issue before the insulation was done.

The insulation was done with the labour version of the green new deal ie was grant-funded. I still have the 25-year guarantee for what it’s worth. My understanding is the roof was done but I’m pretty sure the walls too.

Since the works were done it has been rated C (EPC). The current tenants ensure the house is ventilated when drying/washing clothes etc.(which can sometimes cause issues).

The house is a terrace built around 1890ish. Please find attached a picture of the mould (main pic). Hope that helps. I’m at a loss but if you/the readers ask me anything – I would try my best to answer.

My late mum did say mould periodically returned, but it despite the passing of 3 decades it seems to have only become an issue shortly after the insulation.

Any thoughts/ideas/recommendations as to what to do?



Simon M

11:10 AM, 11th April 2022, About 3 months ago

Reply to the comment left by JohnCaversham at 11/04/2022 - 09:45
This sounds a good description to me. Check the recommended issues first to identify if it's an issue that would affect any house.
If none of these are the cause then it would appear to be because it was built with lime mortar and lime plaster, which are permeable to allow the building breathe through the walls.

Claiming on the guarantee may buy more years or replace with the wrong materials, that will fail again. I'd recommend you get in a lime plasterer or similar. They'll tell you what needs to be done to fix it permanently, and should identify compounding problems like raised external levels, boarded-up chimneys etc.

Kate Mellor View Profile

11:19 AM, 11th April 2022, About 3 months ago

Some excellent responses. If you don’t feel equipped to diagnose the issue yourself it can be more cost effective to consult a damp specialist to have an expert diagnosis so you can spend your time and money fixing the specific cause rather than trial and error. It shouldn’t be too expensive to fix, but it’s frustrating for both yourself and the tenants to keep patching over the issue.

Mick Roberts

11:19 AM, 11th April 2022, About 3 months ago

I've had loads like this. Had about 50-70 houses done on the free schemes when the introducers were desperate to get their commission & we got sucked in with free insulation.
Some have said it on here, we got to be careful this time with the Free EPC upgrades coming to us.

Funnily enough, my Landlord mate used to own the big Midlands firm Warm & Cosy, he said when done properly, he never had any problems.
He said the 25 year guarantee is with SEGA.

g gorton

11:54 AM, 11th April 2022, About 3 months ago

Have had a similar problem in a house built in the 1970's - problem of mould arose after cavity wall insulation and installing double/triple glazing - solution installed an automatic environvent ventilation system in both the bathroom & kitchen with a ventilator in the hall off which all rooms are linked - this solved the problem as the ventilator fans extract any ambient moisture as soon as an increase in moisture is detected - hope this helps


12:05 PM, 11th April 2022, About 3 months ago

if 1890 built, then walls unlikely to be insulated, only option for those is external or internal insulation, which you would be able to see, and is highly expensive.
if only low level, then rising or penetrating damp, or seal of window to wall.
could be condensation, but that is usually high level. even breathing produces moisture and it has to go somewhere.
best solution i found in rented properties was positive ventilation. it slightly raises the air pressure inside and pushes moisture out through the walls. cured problems in several properties where we had recurrent problems before.

Andy 46

12:43 PM, 11th April 2022, About 3 months ago

Look at fitting a NUAIRE 2000 fan they work well at ventilating rooms

Mick Roberts

12:44 PM, 11th April 2022, About 3 months ago

Reply to the comment left by Andy 46 at 11/04/2022 - 12:43
Yes, I have a Nuaire too, seems to work when the tenants don't forget to tell me it was broke & blowing cold hard cause heater had broke.

john speakman

15:25 PM, 11th April 2022, About 3 months ago

I am a landlord and a local builder. I have sorted this problem for myself and many other landlords over the years. It is a solid wall & attracts moisture. The way to cure it is to remove the skirting board, construct a small stud wall under the window ledge using 3 X 2 scant timber and filling the void with at least 60mm of ridge insulation. Board & skim then re-fit skirting board. A decent builder should do this work easily in half a day.

Christopher Holden

17:25 PM, 11th April 2022, About 2 months ago

Wow so much knowledge, great help, one thing I would add is whip off that window ledge and see what is in the cavity, ensure you have access to an endoscope (ebay) and a damp meter, you will have more idea after that.

The insurance company are likely going to bat you away without a report to back you up.

Good luck sorting it


17:56 PM, 11th April 2022, About 2 months ago

One possible element whilst you are checking into everything - a cracked outside window sill

Leave Comments

In order to post comments you will need to Sign In or Sign Up for a FREE Membership


Don't have an account? Sign Up

Landlord Tax Planning Book Now