How can we fix this paint flaking problem?

[80sMum]

Four winters ago, our new (2012 built) flat roof leaked in the severe storms of January 2014. Our builder fixed the problem, or so we thought.

The following winter, it leaked again!

We got a structural engineer in to look at it and took his advice, and our builder carried out the prescribed work, project managed and signed off by the structural engineer.

So, that was early 2015. We left the ceiling to thoroughly dry out for well over a year year and then repainted it in 2016.

It now looks like this! Paint flaking and plaster appears to be crumbling.

What could be causing this? It's not wet. I am wondering if we need to hack all the plaster off and have it replastered?!

I have a feeling yoy didn'y apply a sli, coat on the bare plaser.

Wait until the winter is over and there is no sogn of condensation in the kitchen (you don't dry wet clothes indoors, so you?)

Then lightly sand the surface to move any loose or flaking paint, then apply a coat of Dulux Supermatt, thinned with 50% water, When dry, apply another thinned coat, when dry, two unthinned coats. Stir all very thoroughly.

Supermatt is a non-vinyl paint and allows plaster to dry out through its pores. It is not very durable, but that doesn't matter on a ceiling.

Do you use an effective extractor in the kitchen?

"I have a feeling yoy didn'y apply a sli, coat on the bare plaser."

means

"I have a feeling you didn't apply a mist coat on the bare plaster."

p.s.

parts of the plaster are showing dark brown, which usually means it is damp.

It could be kitchen condensation or it could be leaks.

After sanding, repair it with
www.wickes.co.uk/search?text=joint+plaster
which are more durable than polyfilla or similar.