Plasterboard bowed - what would you do?

RurtBeynolds

I have just moved into a house (80's build), and just noticed that a sheet of the plasterboard in the box room is bowed out slightly from top to bottom. You can see in the picture the crease in the wall down the left side, and what I assume is the outline of the tape over the joint.

It's not really causing me any heartache, but I want to paint the room and feel like I should put the effort in to fix it first. I don't think there is any issue with the wall behind the plasterboard, I can push the plasterboard back by hand so I reckon whatever was fixing the board to the wall has failed. (Not sure if it's a stuff wall or it was dot and dabbed)

My DIY skills don't go beyond changing a light bulb, and feel like I might be asking too much of myself with this.

What would you do?

10-10-20

https://www.boards.ie/discussion/2058276465/plasterboard-bowed-what-would-you-do

Hi!

I'd find the studs behind the plasterboard (https://www.boards.ie/discussion/2058241814/how-to-find-the-studs-behind-plasterboard-wall) and then screw the loose plasterboard into the joists with suitable screws at ~30cm distances, then fill the holes.

The screws should be "black phosphate" drywall types and not wood-screws.

RurtBeynolds

Hey, thanks, I actually hadn't considered that. Worth a shot!

I did say the board flexes back when pushed by hand, but on further inspection it looks like it would take a lot of force to get it completely flush again, I'm not too hopeful about that tbh.

GreeBo

Start from whichever side is least bowed and work your way along

e.g. if the top is the best then screw a line across the top

then move down 12 inches and repeat

Plasterboard is pretty malleable so as long a you dont just try to screw in the middle you should be fine.

C. Eastwood

https://www.boards.ie/discussion/2058276465/plasterboard-bowed-what-would-you-do

The replies above assume that behind the slab is a timber stud partition. I assume it is a concrete block wall.

You said that you recon that whatever was holding the plasterboard slab on to the wall has failed.

If there is a timber stud partition behind the slab - it means that the morans who fitted the slab did not nail the slab correctly on to the timber stud. Almost unbelievable, but happens with the unqualified and incompetent morans today.

You need to ascertain if the surface behind the slab is a timber stud partition or a concrete block wall.

If it is a timber stud, then you can re fix the slab with screws as described above.

In the construction industry items are fixed either chemically of mechanical.

Plasterboard slabs can be fixed chemically with adhesive and / or mechanically with nails or screws.

I would always ensure that slabs fixed to concrete block walls are fixed with adhesive and must also be fixed with metal mushroom fixings.

BED28E55-91AF-45EA-AC34-D85C660F308E.jpeg

If your slab was fixed to a concrete block wall with adhesive only which failed- then the slabs were fixed by unqualified incompetent morans.

If there is a concrete block wall behind your slabs, get 50 mm long metal mushroom fixings and a suitable masonry drill bit. Drill 60 mm deep holes - push the slab tight against the wall, and hammer in the mushroom fixings. Mushrooms fixing should be approx 600 mm vertically and horizontally. Hammer the heads of the mushrooms in appropriately 1.5 to 2 mm beyond the surface of the slabs. Fill over the mushrooms heads with internal Polyfilla, sand paper over and paint.

Saladin Ane

https://www.boards.ie/discussion/comment/120029803#Comment_120029803

I agree with the above poster with the exception of METAL mushrooms. Use plastic as the metal ones cause a cold bridge. And later on you could get round condensation spots. How do I know? I've been there!

10-10-20

https://www.boards.ie/discussion/comment/120062551#Comment_120062551

Except where there is a requirement for metal mushrooms for fire safety - I think you mean. 😁

C. Eastwood

https://www.boards.ie/discussion/comment/120062551#Comment_120062551

It is easier to use metal mushrooms rather than plastic mushrooms fixings.

It is necessary to apply 2 coats of Zinsser BIN Shellac Primer to the heads of the metal mushrooms, before painting, to prevent any surface condensation.

I would not use plastic mushroom fixings.

If there are round condensation spots on the surface of the plaster, it is easy to wash off with a cloth.

10-10-20

"It is necessary to apply 2 coats of Zinsser BIN Shellac Primer to the heads of the metal mushrooms, before painting, to prevent any surface condensation."

Not being picky but that won't prevent condensation if the metal head is colder than the surrounding wall. There are insulative caps which can be added to them, but the insulative effect is minimal and they could still show over time.

Saladin Ane

These walls were skimmed about 10 years ago. Not painted so the condensation spots are now rust spots. I guess a few spots of paint before painting might do the trick.

The rust spots seem to be firm and undamaged.

10-10-20

https://www.boards.ie/discussion/comment/120065130#Comment_120065130

If that's the point of the primer, then yes, for sure!

RurtBeynolds

Small update, looks like the plasterboard is dot and dabbed. I got one of the magnetic stud finders but am not finding any studs (it's an external wall) . How to approach that??

10-10-20

It's probably time to find out if it really is dabbed, why the dabbing failed and what's really behind it.

RurtBeynolds

I had a plasterer out to have a look, he quoted 600-700 to replace the board (it's an insulated board) and reskim the wall (which is less than 2000mm).

Does that seem like a good price?

10-10-20

https://www.boards.ie/discussion/comment/120134436#Comment_120134436

Time and materials? Replace one board like-for-like and what insulation thickness? The boards are about 40 to 90 EUR each.

Would you consider increasing the depth of insulation there while you're at it?

https://www.goodwins.ie/insulated-plasterboards/c-1419.html

Also are there wiring improvements needed or not?

astrofool

https://www.boards.ie/discussion/comment/120134436#Comment_120134436

I'd be asking them what it cost to re-do the room and get it done properly (with insulated board) before painting it. You would need to put any electric cables into conduits and potentially replace the back boxes as well, but if that room is external facing with dabbed plasterboard, it will be very cold and lose heat very quickly.

RurtBeynolds

What would be the benefit of that? Just to upgrade the insulation?