Overboarding ceiling with plasterboard

raxy · 08-10-2017 05:32PM #1

I am planning on putting fresh plasterboard on the ceiling before getting the room skimmed.
The old ceiling is stippled so thought this was the easiest option. While marking out the joists today I noticed a big dip in a part of the ceiling where the old plasterboard is not secured to the rafters. Can I just put the new board over this or would it need to be repaired first?
I have come across a second issue that I'm not sure about. There is no joist on one side of the room to secure the ends of the plasterboard. Will adhesive be enough to hold the end of the plasterboard or will I have to try run another piece of wood to secure that end? There is a joist at the other end so it's only one wall I have the problem with.

the_pen_turner · 08-10-2017 07:41PM

what is above the room. attic or room

is the slab coming away from the joist, can you shove it a bit. if so screw it back up using washers. no harm in putting a few here and there aswell

DublinDilbert · 08-10-2017 07:42PM

raxy wrote: »

I am planning on putting fresh plasterboard on the ceiling before getting the room skimmed.
The old ceiling is stippled so thought this was the easiest option. While marking out the joists today I noticed a big dip in a part of the ceiling where the old plasterboard is not secured to the rafters. Can I just put the new board over this or would it need to be repaired first?
I have come across a second issue that I'm not sure about. There is no joist on one side of the room to secure the ends of the plasterboard. Will adhesive be enough to hold the end of the plasterboard or will I have to try run another piece of wood to secure that end? There is a joist at the other end so it's only one wall I have the problem with.

You need to get the bow out of the old plaster board, see if you can screw the old board up. If the old board won't pull up take a hammer to it.

Always screw the new board into the joists. Most plaster board is metric in one dimension (1.2m) and imperial in the other (8ft).

What spacing are your joists?

In older houses with 16" joists, I always join the 1.2m sides of the boards on the joists, end to end. If you have 40cm spacing you might want to do the opposite.

Plan your joints. Make up a stand to hold the boards up or rent a lifter.

raxy · 08-10-2017 08:06PM

Joists are 61cm apart so was going to put the 1.2m end along them. The joists would be too far apart to run the other way. It's attic above.
Not sure if I can just screw the bulge back, I've pushed it up but it's quite rigid & stiff. I'll give it a go during the week & see how I get on.
I have a couple of props for holding the boards up & someone to help too.

sky6 · 08-10-2017 08:21PM

In my opinion, it's never a good job to slab over an old ceiling. It's fraught with potential problems. It only takes a couple of Hours to pull an old ceiling down and clean up. Then you can see clearly what you're faced with.
You could then fit an insulated Board to the Ceiling making the room warmer and the need for less heat.
It's a much better job all round and can all be done in 8 to 12 Hours.
good luck with it.

the_pen_turner · 08-10-2017 08:25PM

I would strip the ceiling. its bulging for a reason.
counter baton it with 3 x 2s 400mm centres

then re board with 50mm insulated slab

sky6 · 08-10-2017 08:31PM

the_pen_turner wrote: »

I would strip the ceiling. its bulging for a reason.
counter baton it with 3 x 2s 400mm centres

then re board with 50mm insulated slab

+ 1

landcrzr · 08-10-2017 08:39PM

sky6 wrote: »

+ 1

You'll loose 100 mm of height though? If its an attic, why not just use normal boards and insulate later with quilt?

raxy · 08-10-2017 09:04PM

I already insulated the attic. There's 300mm there so no need for anymore.
What problems are associated with covering what's there?

the_pen_turner · 08-10-2017 09:08PM

no problem but more timber will stop it sagging again.
also 300 mm is marginal insulation. I would go a bit deeper

BrokenArrows · 09-10-2017 09:35AM

Think twice before considering pulling down the old ceiling if its stippled. It might be Artex which could contain asbestos.

sky6 · 09-10-2017 11:13AM

BrokenArrows wrote: »

Think twice before considering pulling down the old ceiling if its stippled. It might be Artex which could contain asbestos.

True if Artex, You need to wear a mask.
Also true you would lose a little height if using insulated slabs. But you won't even notice when the job is done.

But as to double slabbing been there and done that. total disaster mold showing spots on Ceiling just a few Months later.It was a Kitchen Ceiling.

Ended up having to pull it all down again and do the job properly.

DublinDilbert · 09-10-2017 01:01PM

sky6 wrote: »

True if Artex, You need to wear a mask.
Also true you would lose a little height if using insulated slabs. But you won't even notice when the job is done.

But as to double slabbing been there and done that. total disaster mold showing spots on Ceiling just a few Months later.It was a Kitchen Ceiling.

Ended up having to pull it all down again and do the job properly.

I'm interested as to why mold would show up more on a double slabbed ceiling? Have double slabbed quite a few ceilings and never had any problems, but might reconsider going forward if this is an issue.

raxy · 09-10-2017 07:33PM

We're going to batten it out & put boards onto the new battens.
I noticed our kitchen had been double boarded before when I changed the light fitting. We only bought the house last year so have been doing bits as we go along when we can afford it. We haven't noticed any problems in the kitchen. The seal around the bath was gone above it which is probably why it had been done in the first place so if mold would be a problem it should have shown up by now.
When we put new floors in upstairs we had to have some rafters cut out as they were rotten. When using the shower water was literally running down the wall behind the shower.

Overboarding ceiling with plasterboard

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