New plaster cracked

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-sean-

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Hello all, I’m a newbie here, not a plasterer just a DIY’er. Had a go at plastering a small section between two doors at the weekend. Originally took it back to brick but found bricks behind had been hacked and very uneven. Too many high spots so couldn’t board over so tried to flatten as best I could with two coats of hardwall, then did two coats multifinish next day. Looked ok-ish (for an amateur) but then dried and cracked from floor to half way up next to door frame.

Any tips on what I did wrong?

Top half had some wiring channel coming down next to the timber lining so I stuck some scrim tape over it thinking it’d help the topcoat stick, that bit hasn’t cracked. Maybe I needed something over the timber below too.

Reckon if I tape over the crack, PVA and skim again it’ll sort it?

Thanks
New plaster cracked
New plaster cracked
New plaster cracked
 
Sorry they’re not the best photos! Yeah there is a timber frame behind where it cracked, around the door. Looked like some 2” thick timber inside the door lining.

To be honest multifinish may have been way too thick on that side too as I was trying to bring it out a bit to the architrave.

Suppose opening and closing the door might have moved the frame a bit maybe.

Looked ok to me when it was wet, then it dried and a chuffing great crack appeared!
 
The top half where the cabling conduit is seems ok with no cracks (so far!). Crack has appeared from dimmer switch down to the floor on the right hand side.

Maybe I was chancing my luck with the depth of hardwall (probably over an inch in places). Possibly sand/cement would have been better but I think I would have made a right hash trying to get that on the wall!
 
Yep I should think the plastic trunkiin wasn’t fixed properly and it has bounced out! I bet you was ducking about with the architrave after completed n it’s popped
 
I’m thinking a smear of decorators caulk might be worth a try before getting on the trowel again. Save me having to clean plaster from next doors TV aerial or wherever else it ends up when it’s supposed to be going on the wall...
 
Took me ages to do for such a small area mind! Plus it was about 7” wide and smallest midget trowel was 8” I think, so got cheapest one I could find in wickes and had to chop it down (yeah that was harder that I thought it would be) then emery the face and edges. Mind you looks like I might get to use it again now!
 
zombie said:
I'm confused by your photos but im thick!

Is there wood behind where it cracked?
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Looks like wood on left hand side , possible to pack out doorframe
Can't see right hand side cos angle of pic and architrave left on ,
Likely cause is not soaking brick enough causing stresses on drying out on two different backgrounds
 
Thanks all. Yeah there was wood on the right hand side packing the frame out aswell. Good point on the old brickwork sucking it in, especially being half bricks bet that makes it worse too on the unfired broken ends.

Maybe I should’ve hacked a bit more brick and stuck some plasterboard in instead.
 
-sean- said:
Thanks all. Yeah there was wood on the right hand side packing the frame out aswell. Good point on the old brickwork sucking it in, especially being half bricks bet that makes it worse too on the unfired broken ends.

Maybe I should’ve hacked a bit more brick and stuck some plasterboard in instead.
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You learn more about plastering from things that go wrong so it's a win in the long run
 
-sean- said:
Thanks all. Yeah there was wood on the right hand side packing the frame out aswell. Good point on the old brickwork sucking it in, especially being half bricks bet that makes it worse too on the unfired broken ends.

Maybe I should’ve hacked a bit more brick and stuck some plasterboard in instead.
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Probably, it's between two doors so plaster is under stress all the time.
 
Dollar said:
Timber legs to fix casings
Back in the day way that is your problem right there’

Your welcome
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Contributing but not enough on its own 9mm on its edge, under soaked wall wouldn't have got enough moisture to do damage IMO
 
bof said:
Contributing but not enough on its own 9mm on its edge, under soaked wall wouldn't have got enough moisture to do damage IMO
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Maybe big lad
You get same issue on over-skims not taking corner dowels off
Back in the day they loved the timber
You have to prep it right as you say

Your welcome
 
tapit said:
I HAVE REPORTED YOU TO THE BRASS DIMMER SWITCH POLICE.
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Lol, yeah that was in the house when we moved in (like 10 years ago) and we’ve never got round to changing it. One of the knobs does nothing so no idea why it’s a double!!?
 
Found a pic of the hardwall base coat, can just about see the timber frame on the bottom right hand side where the scratching stops. And that’s where the crack is too...
New plaster cracked
 
Dollar said:
Maybe big lad
You get same issue on over-skims not taking corner dowels off
Back in the day they loved the timber
You have to prep it right as you say

Your welcome
Click to expand...
On a beaded corner i'd take them out but was just saying as only the face is being hardwalled it's not as likely that in this case there wouldn't have been enough moisture and expansion problems , wasn't dismissing your comment mate
 
-sean- said:
Lol, yeah that was in the house when we moved in (like 10 years ago) and we’ve never got round to changing it. One of the knobs does nothing so no idea why it’s a double!!?
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if you found an old pile of dog s**t ten years ago you would have binned it.
no excuse.
 
As zom said you have a thickness of hardwall up to wood and then just 2mm of skim on top of wood where it meets hardwall
crrrrraaaack, tapit tape would have helped or even scrim where wood meets hardwall
 
Well, update for anyone who’s interested, decided the only way to learn is to persevere and have another ‘crack’ at it. Rubbed it down a bit with some medium grit paper & wiped off the dust. Put some orange scrim tape over it cus orange is a stronger colour than blue apparently, still found it hard to get it to stick. Couldn’t get hold of your tape tapit, where stocks it out of interest? Rollered on some 5:1 PVA and left it a bit then started mixing some multifinish up. PVA’d again and started putting 1st coat on. What a nightmare! I’d made the mix too wet so plastered the floor too, but the main problem was despite the PVA it was setting way too quickly. Could feel it dragging on the trowel, scraping and tearing early on even with a shallow angle on the trowel. Tried not to panic and just get it all covered and coated, but then had to second coat straight after out of same mix as it was going off so quick on the wall had no time to clean up and mix again. Just about rescued with lots of wet trowelling, just have to wait now and see how many cracks appear this time! PVA was an old 5:1 mix I made some time back so wonder if it was too weak and maybe doesn’t keep (it was inside away from frost mind).

Beginning to see now how important the preparation is, and how easily it can all go wrong.

Don’t seem to be able to post pics today.
 
-sean- said:
Well, update for anyone who’s interested, decided the only way to learn is to persevere and have another ‘crack’ at it. Rubbed it down a bit with some medium grit paper & wiped off the dust. Put some orange scrim tape over it cus orange is a stronger colour than blue apparently, still found it hard to get it to stick. Couldn’t get hold of your tape tapit, where stocks it out of interest? Rollered on some 5:1 PVA and left it a bit then started mixing some multifinish up. PVA’d again and started putting 1st coat on. What a nightmare! I’d made the mix too wet so plastered the floor too, but the main problem was despite the PVA it was setting way too quickly. Could feel it dragging on the trowel, scraping and tearing early on even with a shallow angle on the trowel. Tried not to panic and just get it all covered and coated, but then had to second coat straight after out of same mix as it was going off so quick on the wall had no time to clean up and mix again. Just about rescued with lots of wet trowelling, just have to wait now and see how many cracks appear this time! PVA was an old 5:1 mix I made some time back so wonder if it was too weak and maybe doesn’t keep (it was inside away from frost mind).

Beginning to see now how important the preparation is, and how easily it can all go wrong.

Don’t seem to be able to post pics today.
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Not good enough with the PVA , 5:1 probably a bit weak if it's Wickes or bnq should be 3:1 , left for an hour then 2:1 which should still be tacky after 10 min , put first coat on and trowel tape on where needed , if prep is ok in 20 Min approx first coat should start to firm up and put second coat on . No need for water , trowel as little as possible and sand or fill your mistakes when dry
 
bof said:
Not good enough with the PVA , 5:1 probably a bit weak if it's Wickes or bnq should be 3:1 , left for an hour then 2:1 which should still be tacky after 10 min , put first coat on and trowel tape on where needed , if prep is ok in 20 Min approx first coat should start to firm up and put second coat on . No need for water , trowel as little as possible and sand or fill your mistakes when dry
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Thanks bof, yes PVA was cheaper Wickes stuff, mix looked thinner than skimmed milk so yeah I’ll mix a lot stronger if I ever try this again. Used same bag of plaster, in date and under cover outside but been open a few weeks now so maybe it’s got a bit damp in storage too. I left it a bit long in the bucket while typing up on the forum and it stiffened up and was a beggar to get out and clean up, lesson learned there too.

Finish not quite like the first time but may not notice when painted and like you say I could always use some sanding and a bit of filler if needs be.

Just gotta wait and see what happens as it dries now.

New plaster cracked
New plaster cracked
 
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