Paint Peeling In Converted Garage - What To Do Next

[Rosyherb5]

We recently insulated our garage and having some problems.
1 we insulated the ceiling and walls by plaster boarding
2 we painted it. having left time to dry plaster, and used a mist coat. 1 half is Trade Magnolia and the other half is pale blue Dulux paint
3 The walls went black with mould and the up and over door, which we forgot to insulate was wet with condensation.
4 we treated the mould and got a heater and condenser to dry it out
5 we put a 2nd coat on the blue using the same paint
6 went in yesterday and random patches of paint has bubbled and peeled and bare plaster is now showing.
What should we do now!

[woofgang]

what's the air circulation like?

[MargoTester]

Bump - can you help with this Builder?

[The Builder]

That's a shame, Rosy, but
First thing... plasterboard does nothing to introduce insulation, unless it has insulation put behind it.

I'm afraid you only have to look at the weather. With an up and over door, there will be a permanent current of cold, very damp air right through the garage.

You will always have condensation. I'm afraid the paint has nothing at all to do with it.

I wouldn't even think of heating and/or de-humidifying. With the door there, all your work is in vain.

If you want to turn the garage into a proper, habitable room, then you must consider removing the door and filling in with a timber frame fitted with full insulation. (Plus insulating the walls.)

I hope I haven't spoilt your day.

[The Builder]

Haha Margot.... I was writing ;o)))

[Rosyherb5]

The Builder,
We did insulated behind the plasterboard.
The door we had insulated too and covered it in PVC cladding (white tongue and grove look to stop the mould coming back, and put a wide seal round to cut the most of the drafts.
The 1/2 that is magnolia is fine it is only the blue 1/2 that bubbled and peeled, and that was only after we put another coat on.

[The Builder]

Ah, you're back, rosy?
Sorry I've only just seen this.

Thanks for the further info. The trouble is, I still don't like all the black mould and condensation, although, from what you said in your original post, you might have overcome that.

I often have to jump to conclusions on this site, since we don't get all the necessary information right away.

You say the blue was regular Dulux?
It could be that. Trade paint is non-vinyl (breathable).
Normal Dulux and others are vinyl. Perhaps the plaster had not dried out sufficiently before painting. That would do it.