Foil backed plasterboard

[Robbox]

In our old stone house, a couple of window reveals have a problem with excess dampness penetrating from the outside wall. So any paint just peels off eventually. Before anyone asks, the outside wall has been repointed and treated. But the wall faces due west and gets battered with wind and rain, eventually moisture does penetrate.
I'd like to face the reveals with foil back plasterboard, thinking that any moisture will not get through and disrupt the paint finish.
Since the area is quite small on each reveal, I was thinking to simply use a good grab adhesive.
Comments?

 

[jeds]

More likely to be condensation due to cold bridging around the window edges. My advice is hack the plaster off the reveals and replace with insulated plasterboard. That will stop it dead either way.

 

[tomfe]

+1 to jeds.
If it's not that you could go with lime plaster and a breathable paint.