Mould under 1930 bay window

[chrisjjr1980]

Hi, this is my first post and not sure what to do or which trade would be best to help with mould under the bedroom bay window.
It’s a 1930s semi. The room is well heated and ventilated and this is the only area of the room that is affected.
It isn’t wet to touch but is cold.
My thoughts are that moisture or rainwater may be getting in through the render. It wasn’t in good condition when we moved in but we filled it and painted it and had no issues since. New windows fitted this year but no trickle vents?
I have tried to clean with anti mould spray but keeps coming back.
Would I be best getting it replasted and insulted and/or hack off the render and re render it? I’m a bit of a novice so would need a tradesman and I think a plasterer would be best suited but would welcome any ideas or suggestions. This is the only area of the house that has some mould. Thanks

 

[cross thread]

If same as mine it will be a single skin with a damp proof barrier,I knocked my render off and fitted new barrier and insulated the inside wall .

 

[JohnD]

Yes. The construction may be very insubstantial. You can also address it by breaking off the internal plaster, you will probably find a wooden frame and a cavity. Clean it out, pack with insulation, finish with a moisture-vapour barrier, plasterboard, and redecorate.

Because the upper bay was built on top of the old wooden window frame, there may be no brickwork.

Mine was tile-hung, and I would have added breathable membrane if rebuilding from the outside.

 

[^woody^]

Classic pattern staining from condensation.

It may be that the only practical way to deal with this is to take the plasterboard off and insulate between the frame and across the face.

 

[JohnD]

And it will be easier than working from the outside.

 

[chrisjjr1980]

Thanks for the replies.
Assuming the work was done from the inside as suggested would there still be potential issues with the render from the outside letting moisture in? Or are you saying the mould is caused by the condensation inside the property?
Sorry if I’m being thick but don’t want to fix the inside and then have to re render too, thanks.

 

[^woody^]

Render does not let water through it unless it's cracked or suchlike. The symptoms there are of condensation not water penetration.

 

[chrisjjr1980]

Thanks, the render wasn’t great but we patched and painted it a few years ago and no issues since. Looks like we will get somebody in to do the work from the inside insulate etc, thanks all

 

[JohnD]

... Looks like we will get somebody in to do the work from the inside insulate etc, thanks all

DIY

Why not?

 

[Jonesy85]

I too have the same issue. Thanks all for the information. I prefer to do most home improvement jobs myself, however I can't dedicate the time anymore. Can anyone advise the type of tradesman to get out to quote for it?

 

[chrisjjr1980]

Hi, I’ve had a plasterer quote me £580 plus VAT for 100ml kingspan plasterboard and skim. It seems steep but it’s a small job so there’s always a premium. I’ve only sent him pictures so far but I might ask him to re render the outside too.

 

[JohnD]

Is he going to pull off the old plaster?

 

[chrisjjr1980]

Yes

 

[JohnD]

That should be enough.

You might find other problems inside, like woodworm or rot or water leaks.

Get a builders canister vac and some dustsheets for the room. Clean it out and I would apply a timber preserver. You could open it and clean out before the plasterer arrives.

There will be a lot of dust and dirt.

 

[noseall]

Thanks, the render wasn’t great but we patched and painted it a few years ago and no issues since. Looks like we will get somebody in to do the work from the inside insulate etc, thanks all

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