Mould on internal wall

[DIYJenny]

I rent out a small studio flat and my tenant constantly complained about being cold despite the fact there was plenty heating available (albeit electric). He has just moved out and I found a lot of black mould on the wallpaper in the vestibule at the the front door. I believe the tenant probably did not heat or ventilate the flat sufficiently. I have removed the mouldy wallpaper but on the plastered wall behind, where the mould was, there is a white coating over the plaster and this had black mould on it. This makes me think there has been a problem in the past and a previous owner has put some damp proof paint on the plaster. I have had the property for 20 years and this mould problem has just shown up now so whatever was put on worked well.

My question is - what do I do now? Do I clean it all up with a mould remover I can buy in a supermarket, paint on some anti mould product on the plaster then rewallpaper and emulsion.

I have had a dehumidifier in the flat for a couple of days but so far hardly any water collected so don't think there is a major problem with damp. I believe it was condensation due to lack of heating and ventilation.

Thanks to all for any kind assistance.

 

[sircerebus666]

Have you turned on the heating full blast and seen if the electric heating warms the flat sufficiently?

I find it very hard to believe that your tenant would constantly complain of being cold yet put no heating on.

This suggests you have an issue that needs sorting simply slapping on some more anti damp paint which will mask the problem not sort , will not fix the issue

Did you investigate your tenants complaint or simply dismiss it out of hand ? (I suspect the latter)

 

[DIYJenny]

I most certainly did not dismiss my tenant's complaint out of hand. I was hoping for some constructive help and not a thinly veiled suggestion that I am not a conscientious landlord.

 

[opps]

The white mould sounds like it might be effervescence (salts rising to the plaster surface). I would normally associate that with incoming damp rather than condensation. I could be wrong though.

If it is then you need to deal with the potential damp rather than condensation. Effervescence often requires oil based alkali resistant primers, but they will fail if the root issue persists.

I would not expect a "damp proofing" paint to prevent the salts from blistering the paint.

Worst case scenario it might be dry rot. If it is then most firms will chop away any plaster up to a meter from where it was last seen and use chemical and render the wall (after they determine the cause).

Photos will help.

 

[DIYJenny]

Thank you very much for your helpful reply.

 

[endecotp]

I believe it was condensation due to lack of heating and ventilation.

Do you have a working bathroom extractor? Kitchen extractor?
What have you provided for drying clothes?

It’s not unusual to get some condensation-related black mould on the coldest patch of wall in a property - the excess moisture will condense at the coldest spot. You’re lucky it’s in the vestibule, rather than e.g. at the foot of a bed ruining the bedclothes.

 

[DIYJenny]

Thank you. Yes there is an effective bathroom extractor and kitchen extractor. I provided a tumble drier but it looked as if it hadn't been used. I think you are correct that the moisture has condensed at the coldest spot and this is the area I need to address.