Damp? Old paint came off easily on an external wall

We were about to paint the back of our living room when I noticed a crack between the doorframe and the wall. As I started stripping around the crack, I realised that the old paint on that wall (an external wall) came off really easily. Wonder if there's any problem with the wall please? I've now stripped most of the old paint off but can't see any obvious signs of damp. And what shall I do now? Mist-coat and paint?

Any comments and advice would be much appreciated! Thanks!

Does it come off the other walls just as easy?
How old is the house? How old is the paint job?

I'm in no way an expert but painting gypsum (pink) plaster without prepping it first (a few watered down coats of emulsion) can cause it to not adhere / form a skin that can be easily peeled.

If it was damp I'd expect the plaster to look less colour uniform or be blown a bit or show tide marks

Sure others with more knowledge will help.

jacko555 said:

Does it come off the other walls just as easy?
How old is the house? How old is the paint job?

I'm in no way an expert but painting gypsum (pink) plaster without prepping it first (a few watered down coats of emulsion) can cause it to not adhere / form a skin that can be easily peeled.

If it was damp I'd expect the plaster to look less colour uniform or be blown a bit or show tide marks

Sure others with more knowledge will help.

Click to expand...

Thanks Jacko! We haven't tried to strip off the paint off other walls yet. It's 1930s terrace. The top coat of the paint doesn't look that old but is not very new either. It's like a washable one with a bit of shiny surface, which is probably explained by the previous owner having three young kids. We moved in last Oct, and didn't notice any obvious damp spots in the hosue over the winter.

Crappy paint job, slapped it on thick without any mist coats or prep, possibly before the plaster had a chance to dry.

You could always try the polythene trick to check for damp.
Tape a square of polythene onto the wall, tape all edges, and see if any moisture appears underneath.