Bubbling/blistering paint that grows a beard!

[lisainthemedia]

Hoping you can help us! I'm talking about a wall in our dining room. The room is a 1980s extension and the wall is external facing, although there's about a foot gap between the wall and our neighbour's extension. Ground floor.

Last year when we had buckets of rain we noticed a large area of blistering/bubbling paint at the top of the way, so a goo 7ft or so up. We scrapped off the paint, got in a dehumidifier as the wall looked damp and over the course of a few weeks the patch went fuzzy like a white beard and lots of slats came out, which we scrapped off. When it stopped crusting we used uPVC sealant (watered down) then painted again. The dining room has a flat roof so I check the drain pipe that runs across the flat roof and there was a loose connection right above the patch so I thought mystery solved! 12 month on and all is good.

Now the bubbling/blistering is happening again in another location. This time about 1 ft up from the skirting board on the other end of the way. Not such a big patch but it is growing. And we've had so much rain! Could it be rising damp? We've not touched it yet hence my post.

My neighbour is a builder and he did something to the external side of our way while doing his extension. He said it was something safe but I have a feeling he's taken some render off. What should I do next? We're hoping to sell this house soon so we don't want damp being picked up in the survey but we don't want to be ripped off by a damp company saying we need ££££ of work done.

TIA

 

[dcdec]

Its efflorescence. Dampness in the walls is coming to the surface and bringing salts in the plaster with it. You have a damp issue which needs to be sorted, not exactly sure what you mean by UPVC but sounds suspiciously like you mean pva which is a bad move. Once damp is fixed just brush of salts, scrape off paint, prime, fill, rub down, prime filler and paint, however if you have pva'd it this may not work. If your builder neighbour has seen your wall and didn't recognise efflorescence he's no builder but if he hasn't show him and he can investigate the source of damp.

Any attempt to wash off will make it worse, dry brush only.