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Questions on Plasterboard Ceiling - Should you Only Use Drywall Screws?

Postby Zacccc » Mon Sep 29, 2014 12:11 pm

I've just put up a PB ceiling in a small bedroom. I was using "Easydrive BZP Fine Thread Drywall 100mm" screws, which I couldn't get fully into the joists (left about 20mm sticking out) so I've now used 5.0 x 90mm multipurpose ZP screws and they've done the job.

I think the problem might have been that I was using twin thread drywall screws which are fine thread whereas to go into joists I should have been using coarse thread. I realized this too late. The screws I've used are zinc plated so I can't see them causing any problems for me but am I right in this assumption or is there some reason that you should only use drywall screws for putting up PB.

It's my first go at putting up a PB ceiling and unfortunately it's not that clever. The ceiling's only 8ft x 6ft so I just needed two 8 x 4 boards. Unfortunately, working on my own, I managed to break one of the boards in half and then I cut some sections of board, forgetting to match to where the joists are. So the result is a bit of a dog's breakfast, with the ceiling now comprised of 9 different sections of PB.

Also, there is a 50mm insulation slab between the PB and the joists (hence the 5 x 90 screws) and it is a sloping ceiling which sort of curves at the top of the slope. Because of these two factors I haven't been able to get a couple of the sections to butt up against each other perfectly, with one side a mm or 1.5mm proud of the other and there's one length of about 20 cm where the PB on one side is about 7 or 8 mm proud of the other side. I'm going to get a pro in to do the plastering and am wondering if he'll be able to mask this without too much trouble. Also, someone told me I should have left a 2 to 3mm gap between sections, which I haven't done - will this be a problem to the plasterer?
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Postby thedoctor » Mon Mar 09, 2015 4:47 pm

The plasterer wil lbe able to tape the joints and use some one-coat or patching plaster to smooth out where the boards aren't flush so don't worry, just tell him he will need a small bag of one coat before he comes.

The zinc plated screws sometimes lose their plating when a driver is used on them. This exposes the steel which can rust when the water from the plaster hits them. This can leave little brown spots on the ceiling which need stain block to cover them when decorating as the rust keeps "bleeding" through.

That's why dry wall is used.

This can usually be overcome by applying some decorators caulk to the head of the screws before plastering. Smooth it out so it fills the hole and seals the screw in.
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