# Forum Home Renovation Plastering  Sagging fibrous plaster ceiling and cornices

## ausdb

Hi All 
A bit of background first, I have an old mid 1950's house in the Perth suburbs with fibrous plaster ceilings which have sagged to varying degrees as the plaster saddles have let go due to time and in a couple of places water entry. My wife has been hassling me for years to sort it out and with bub no1 about to arrive in a few months this can no longer be ignored "lest the ceilings fall down whilst mothers group is at our house"  :Shock:  
I have done a lot of reading on the forum on how to rectify this and chose the method of propping the ceilings up with planks and acrow props and then restrapping with fibreglass rovings and cornice cement. I decided against screwing the sheets back up as the plaster seems to crack easily (it was sagged about 50mm in some places) and the jarrah ceiling joists are 60 years old and really hard so gyprock screws just snap their heads off when you try to drive them in. I am not sure exactly how much plaster / rovings I should be using for each strap but where there was a strap every 600mm I have now decreased this to a strap every 400mm or so, depending on how sagged the plaster was. I have attached a couple of progress photo's if anyone is interested or wants to comment on my lack of plastering skills. Obviously I have omitted the step of vacuuming the ceiling and removing 1/2" of dust and flaking clay roof tiles  :Biggrin: .    
Anyway now that I have got the ceilings up somewhere near level and a lot closer to the joists than they have been for a very long time, the next dilema to solve is how to get the cornices back up where they should be! as there is now a gap which has opened up between the sagged cornices and the refixed ceiling.  
In the room I am doing at the moment it has quite a large decorative cornice which is about 7" x 7" in size, I tried to get a replacement for it a few years back with no joy so I don't want to destroy this if possible. What I am thinking is that I will get a 2x1" batten and sit it up against the outermost step of the cornice and then get some large hex drive screws and screw the batten up through the cornice and plaster into the ceiling joists above. Then over a period of a few weeks tighten the screws to slowly bend the cornice up to the plaster again. My concern is that if I apply too much pressure to this of the cornice it will pop the other side off that is still fixed to the wall  :Cry: . I am hoping that as it is now winter and a bit damper there may be enough give in the cornice to achieve this if I do it gradually. The photo's below hopefully explain the situation better than I have, can anyone offer any other suggestions or methods?     
My final question is how to fix up the small hairline cracks in the plaster sheets which have been presnet for a while with a few new ones that have also opened up. What should I use and do I need to try to remove the old paint before I try to fix the cracks? 
Cheers 
Darryn

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## Rod Dyson

> Hi All 
> A bit of background first, I have an old mid 1950's house in the Perth suburbs with fibrous plaster ceilings which have sagged to varying degrees as the plaster saddles have let go due to time and in a couple of places water entry. My wife has been hassling me for years to sort it out and with bub no1 about to arrive in a few months this can no longer be ignored "lest the ceilings fall down whilst mothers group is at our house"  
> I have done a lot of reading on the forum on how to rectify this and chose the method of propping the ceilings up with planks and acrow props and then restrapping with fibreglass rovings and cornice cement. I decided against screwing the sheets back up as the plaster seems to crack easily (it was sagged about 50mm in some places) and the jarrah ceiling joists are 60 years old and really hard so gyprock screws just snap their heads off when you try to drive them in. I am not sure exactly how much plaster / rovings I should be using for each strap but where there was a strap every 600mm I have now decreased this to a strap every 400mm or so, depending on how sagged the plaster was. I have attached a couple of progress photo's if anyone is interested or wants to comment on my lack of plastering skills. Obviously I have omitted the step of vacuuming the ceiling and removing 1/2" of dust and flaking clay roof tiles .    
> Anyway now that I have got the ceilings up somewhere near level and a lot closer to the joists than they have been for a very long time, the next dilema to solve is how to get the cornices back up where they should be! as there is now a gap which has opened up between the sagged cornices and the refixed ceiling.  
> In the room I am doing at the moment it has quite a large decorative cornice which is about 7" x 7" in size, I tried to get a replacement for it a few years back with no joy so I don't want to destroy this if possible. What I am thinking is that I will get a 2x1" batten and sit it up against the outermost step of the cornice and then get some large hex drive screws and screw the batten up through the cornice and plaster into the ceiling joists above. Then over a period of a few weeks tighten the screws to slowly bend the cornice up to the plaster again. My concern is that if I apply too much pressure to this of the cornice it will pop the other side off that is still fixed to the wall . I am hoping that as it is now winter and a bit damper there may be enough give in the cornice to achieve this if I do it gradually. The photo's below hopefully explain the situation better than I have, can anyone offer any other suggestions or methods?     
> My final question is how to fix up the small hairline cracks in the plaster sheets which have been presnet for a while with a few new ones that have also opened up. What should I use and do I need to try to remove the old paint before I try to fix the cracks? 
> Cheers 
> Darryn

  Good job of the scrimming,  The problem is that the cornices are fixed in place along the wall, (maybe had cracks filled in the past).  The only way to lift them as well is to cut the bond on the wall and push them up with a prop much as you have done with the ceiling.  Not an easy job but can be done.  You would need to screw the cornice in place with long screw when done.  
The alternative is to fill the crack along the ceiling line but this wouldnt look so good.  You would need to to use a saw blade to cut along the bond on the wall.  I would just use a panel saw. 
The small hair line cracks can be repaired by skim coating the ceiling with top coat. Then sand. 
Cheers Rod

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## ausdb

Hi Rod
Thanks for the reply but I am unsure what you are saying is going to fix the problem as from close inspection from below and in the roof the cornices have never been re-fixed to the wall. The top "flange" of the cornice itself has sagged down as it was the only thing supporting the plaster ceilings at the edges. What I am trying to do is unsag it without popping it off the wall which is why I am thinking of supporting the upper flange and slowly trying to lift it back so that it is 90° from the walls again now that the ceilings are back up near the joists. 
Also for Browny here is picture of the fibreglass rovings, at the big green megashed they are normally kept out with the builders supplies with the gyprock stuff.

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## CPE W&C

ausdb, 
Its pretty much trial and error with jobs like this. Id be trying the simplest way possible first, which is screwing the cornice straight up into the joists using 45mm-65mm screws. The cornice shouldnt pop off the wall, it would take a lot of pressure for that to happen. Try a small length first, and once you have the cornice touching the ceiling again, loosen and fill with cornice cement. Screw cornice back up, then straight stop the top, fill and polish screws divots and clean down... If it doesnt work, try a straight length of timber and acro props over a period of hours or a batten and screws... 
There is no 'right' way for jobs like these, just keep trying things until you succeed  :Wink:

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## browny

Thanks for the pic - found the rovings at a local decorative plaster place. They didn't call them rovings though so it took a little while to get everyone on the same page.  They actually make them in house with some sort of machine that teases out the raw fibres from a 'cheese' (I've figured out this is what they call a spool of fibreglass). 
For anyone else in Newy after this sort of thing, Thomas Decorative Plastering in Edgeworth is the go (need to call ahead if you're after the rovings)

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## Sooj

I know this is an old thread...but I have  same vintage house, similar problem...only I have been trying to prevent the problem long before it gets this bad...I've been re-strapping too before the ceiling sags more than a few mm.  (house is 1958, horsehair strapping).   
What did you do to solve the gap problem with the cornices? Mine are very very similar type but not sagged as much as yours.   I'm concerned at putting in the screws as the plaster is fragile and may crack the cornice more. 
The cornices are pulling away from the wall and I seem to have to fill them every couple of years, is there a product that woudl be best to do this? I've been using cornice cement, PVA mix. 
Spent a lot of time in the ceiling in recent rewiring effort  and noticed need to do some more, preventative  re-strapping.   Should I mix in some adhesive into the cornice cement to put up the rovings mixture - will this help at all?  Many thanks Sue    

> Hi All 
> A bit of background first, I have an old mid 1950's house in the Perth suburbs with fibrous plaster ceilings which have sagged to varying degrees as the plaster saddles have let go due to time and in a couple of places water entry. My wife has been hassling me for years to sort it out and with bub no1 about to arrive in a few months this can no longer be ignored "lest the ceilings fall down whilst mothers group is at our house"  
> I have done a lot of reading on the forum on how to rectify this and chose the method of propping the ceilings up with planks and acrow props and then restrapping with fibreglass rovings and cornice cement. I decided against screwing the sheets back up as the plaster seems to crack easily (it was sagged about 50mm in some places) and the jarrah ceiling joists are 60 years old and really hard so gyprock screws just snap their heads off when you try to drive them in. I am not sure exactly how much plaster / rovings I should be using for each strap but where there was a strap every 600mm I have now decreased this to a strap every 400mm or so, depending on how sagged the plaster was. I have attached a couple of progress photo's if anyone is interested or wants to comment on my lack of plastering skills. Obviously I have omitted the step of vacuuming the ceiling and removing 1/2" of dust and flaking clay roof tiles .    
> Anyway now that I have got the ceilings up somewhere near level and a lot closer to the joists than they have been for a very long time, the next dilema to solve is how to get the cornices back up where they should be! as there is now a gap which has opened up between the sagged cornices and the refixed ceiling.  
> In the room I am doing at the moment it has quite a large decorative cornice which is about 7" x 7" in size, I tried to get a replacement for it a few years back with no joy so I don't want to destroy this if possible. What I am thinking is that I will get a 2x1" batten and sit it up against the outermost step of the cornice and then get some large hex drive screws and screw the batten up through the cornice and plaster into the ceiling joists above. Then over a period of a few weeks tighten the screws to slowly bend the cornice up to the plaster again. My concern is that if I apply too much pressure to this of the cornice it will pop the other side off that is still fixed to the wall . I am hoping that as it is now winter and a bit damper there may be enough give in the cornice to achieve this if I do it gradually. The photo's below hopefully explain the situation better than I have, can anyone offer any other suggestions or methods?     
> My final question is how to fix up the small hairline cracks in the plaster sheets which have been presnet for a while with a few new ones that have also opened up. What should I use and do I need to try to remove the old paint before I try to fix the cracks? 
> Cheers 
> Darryn

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