Tabby wrote:
On Jan 22, 6:37 pm, GMM wrote:

So...What's the best thing to do? Use foil backed square edge, which
will either need skimming or a bit of luck to get a good finish, or
use tapered edge and stick some foil on the back? The latter sounds
attractive but I might be missing something - like what's the best
way of sticking foil to plasterboard?

With a dead man and small 9mm boards you should have little problem.

The traditional method is under some concrete in the basement.

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Bartc