mould behind picture in new extension

twohooter_2

I had an extension built on the rear of my home earlier this year. It is a well ventilated room built with external face brick work, cellotex insulation, block work and full plaster. After the work was completed, I hung a large picture on the external wall and have today removed it to find a huge patch of 'dusty' green damp. I am really worried as the other walls appear fine. The room does not suffer with condensation and is generally kept at an even temperature. I need to call my builder back in - is there anything I should be asking/checking with him? Thanks

Rain_Shadow

How long after the work was completed and the decorating done did you hang the picture?


Was the picture hung from a hook and wire or screwed flush to the wall?


Sounds like the wall was still damp and a large flush fitting panel just wouldn't let it escape. I've had an extension built this year and the drying out times are a lot greater than you might think.

twohooter_2

Thanks for your reply. The building work was completed in April and the picture hung about three weeks after (by the builder). So maybe, the wall was still damp? The picture was hung with picture hooks and string. There is a reasonable gap - but maybe not enough to allow sufficient air flow. I have checked the external wall and there is no problem with water getting in from outside.

Rain_Shadow

twohooter wrote: »

Thanks for your reply. The building work was completed in April and the picture hung about three weeks after (by the builder). So maybe, the wall was still damp? The picture was hung with picture hooks and string. There is a reasonable gap - but maybe not enough to allow sufficient air flow. I have checked the external wall and there is no problem with water getting in from outside.

Almost certainly caused by residual damp. If it was me I'd clean up the wall and repaint it. Then give it a couple of weeks and rehang the picture. After the summer we've had your walls will be dry by now.

twohooter_2

Thank you so much for your help Rain Shadow - you have been very reassuring. To be honest I rather panicked when I saw behind the picture. My build was not without issue and consequentyly my confidence isn't very high at the moment. Hopefully, a good wash down with disinfectant, a repaint and time to dry as you suggest, will do the trick.

Kiran

Check what the wall looks like after you've cleaned it, depending on the paint that was used previously you may want to stain block it before re painting

Rain_Shadow

Kiran wrote: »

Check what the wall looks like after you've cleaned it, depending on the paint that was used previously you may want to stain block it before re painting

Good point. :beer:

twohooter_2

Thank you very much Kiran and Rain Shadow for your help. The builder came to take a look and between us we wiped down the wall with kitchen towel dampened with detox and also the back of the picture. The picture is rather large and the patch of mould was circular and about 2.5ft in diameter. The mould was like fine green dust and came off very easily. The wall had been painted with a mist coat plus two coats of emulsion. Wiping off the mould took it back to plaster pretty much. The builder reckons (and I think he is right) that it is a case of condensation mould as the wall had not properly dried out before he hung the picture. As the picture does not have a large gap behind the 'dampness' from the wall drying out hit the back of the picture and had no escape. He is coming back next week to apply a stain blocker and then will repaint. When the picture is re hung I will ensure the wall is properly dry and will look into a fitting that holds it a little further away from the wall if this is possible to allow air circulation. Again, thanks guys - I really did appreciate your replies in my hour of panic!