Plasterboard - cracks at joins

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realstokebloke
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Plasterboard - cracks at joins

Post by realstokebloke »

Hi., Redecorating a spare bedroom and, (like a lot of rooms in our house u/f), on a decent wall run where the platerbords meet, cracks always appear - even when they have been deep filled previously by me last time.

They look fine and smooth as at the time but the cracks / splits always reappear.

(By "deep filled" I mean, I scraped out the joint to a decent depth and filled completely with polyfilla.)

Is there a more reliable way of sorting this to last anyone know please? Maybe a more flexible filler (which?).

Or maybe screwing them tight (plasterboard screws I assume) one to the other and filling over the top? As far as I can tell (& without digging in, between the boards and ruining the joint completely, there is no baton behind on such joint is there (to screw into) for greater rigidity?

Corners

Also the same at certain plasterboard corners - where a tiny skim of plaster barely covers the jointing mesh. This also cracks and so with the skim removed all you can see is the gap into any cavity behind.

Would i be better trying to get something in / through and behind the mesh if you like so that, again, any filler over the top will be more stable?

btw, we're talking a mid 90s 'build' (I use the term loosely as it was cleared 'cobbled' toghether by complete cowboys as far as I can tell).

Surely I can't be alone with this problem, so any advice gratefully received. Thanks in advance.
stevei
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Plasterboard - cracks at joins

Post by stevei »

For corners or where plaster meets wood as in skirtings and architrave, I would use a good quality caulk also known as painters mate and other names. Pollyfilla tends to used as a generic term and can be either ready mixed or powder. I always use powder as I think it performs better than ready mixed and lasts longer. Keep the bag sealed between use and store in the house. Mine is in one of the kitchen cupboards. I use this stuff https://www.screwfix.com/p/toupret-powd ... -2kg/4911h but in 1kg boxes.
realstokebloke
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Plasterboard - cracks at joins

Post by realstokebloke »

Thanks, however, that's pretty much what I have done previously and they still seem to split / crack.

Would there be any value in applying one of the 'sticks everything' building glues into the seam and let it go off behind before any layers of polyfilla for example?
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Razor
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Plasterboard - cracks at joins

Post by Razor »

If there's movement due to lack of support the plaster will always crack.

I would drill some holes and use expanding foam carefully to fill the cavity behind the boards.

If the room gets smaller you have used too much :lol: :lol: :lol:
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realstokebloke
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Plasterboard - cracks at joins

Post by realstokebloke »

Thanks razor.

I thought of that but will that actually bind it as such? Surely the plasterboard will just 'slip' at the back where the foam butts up to it?

(Hence the idea of a bonding / glue as above.)
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Plasterboard - cracks at joins

Post by realstokebloke »

Razor wrote:
Tue Dec 08, 2020 12:25 pm
If there's movement due to lack of support the plaster will always crack.

I would drill some holes and use expanding foam carefully to fill the cavity behind the boards.

If the room gets smaller you have used too much :lol: :lol: :lol:
Revisiting some time later with a report back ...

Yup, tried that thanks again Razor.

Have used the expanding adhesive foam down the seams so it hopefully bonds behind as well. It has certainly filled it out behind and in the cavity - so the whole joint feels more solid.

Early dyas but, after a fill and sand (repeat severally ...) they seem to be 'good' and holding so far. Great tip, thanks.
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London mike 61
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Plasterboard - cracks at joins

Post by London mike 61 »

realstokebloke wrote:
Tue Feb 23, 2021 1:16 pm
Razor wrote:
Tue Dec 08, 2020 12:25 pm
If there's movement due to lack of support the plaster will always crack.

I would drill some holes and use expanding foam carefully to fill the cavity behind the boards.

If the room gets smaller you have used too much :lol: :lol: :lol:
Revisiting some time later with a report back ...

Yup, tried that thanks again Razor.

Have used the expanding adhesive foam down the seams so it hopefully bonds behind as well. It has certainly filled it out behind and in the cavity - so the whole joint feels more solid.

Early dyas but, after a fill and sand (repeat severally ...) they seem to be 'good' and holding so far. Great tip, thanks.
Thanks for the feedback, it’s always useful when we hear first hand that something has worked.

Mike
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Razor (Tue Feb 23, 2021 5:11 pm)
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If it ain't broke, don't fix it!!
realstokebloke
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Plasterboard - cracks at joins

Post by realstokebloke »

Not a problem.

Basic good manners.
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