Re-plastering painted window reveal...

[AlexW]

One of our window reveals (18" deep, 1m high, 2.5m wide) was plastered in the past with a skim coat over directly gloss paint. The sides of the reveal are painted sand and cement the top is ply (I think).

The skim has flaked away from the paint and in some cases lifted the paint (on the ply).

We have a plasterer in to do our new conservatory and windows next week who is supposed to re-skim this area.

But I was wondering, what is the best preparation for the surface to receive the skim coat?

Thanks in advance,

Alex.

[Andrew Gabriel]

Remove anything that's loose, and anything that might pull off when it gets wet (like wallpaper).

I'm not sure I have an accurate picture in my mind, but the area should probably have been lined with plasterboard rather than plywood originally. Personally I would probably strip out the ply, and depending what's behind, either apply a scratch coat to it (undercoat plaster or sand and cement depending on likelyhood of any penetrating damp), or fix plasterboard instead.

[AlexW]

I may be able to get away with just removing the skim bead on the front top of the reveal and screwing 9mm plasterboard to it (after removing loose stuff) then reinstating some new skim bead.

The sides should strip back to the S&S render, I guess which can then be skimmed directly.

The property is very old and its not clear to me if plasterboard would have been in common use when the ply was put up. I don't want to pull it down though as the rubble infill in the wall might cause a bit of a mess.

Cheers,

Alex.

[Rob Morley]

Scrape the rendered bits to get rid of most of the paint, tack some EML to the ply and give it a thin bonding coat.

[AlexW]

Thanks for the suggestion Rob.

Being a plastering newbie ... Err what's EML?

Cheers,

Alex.

[Rob Morley]

Expanded metal lath - a sort of wire mesh, the same as the perforated bits that hold on metal angle beading, but in a flat sheet.

[AlexW]

Aha, seen it. Did not know what it was called.

Cheers,

Alex.