Patching and Plastering - Help - sagging plaster ceiling

http://forum.doityourself.com/showthread.php?t=348675

I've been recently hanging out in this forum, and just realized that my original post is in walls and ceilings... I hope it's "legal" for me to request some help on this thread without cross-posting.

I have a plaster/drywall lath ceiling and it's getting mushy. I dread taking this out... and dealing with the powdery insulation up there. I bought three different types of fasteners today, none look like a dime head on a screw, but I've concluded that my best bet might be to lightly texture the ceiling once everything is back in place, so the truss or panhead screws won't show. All the flat heads countersink and I think that's where the problems would start. Any advice would be wonderful :o

I don't want to move into this bedroom till I know the ceiling isn't going to fall in :rolleyes:

from reading your other post, it seems as if you have plaster board(16 in wide and maybe 12 ft long). i have the same thing in my house(circa 1948). when it sags, the only way to repair is to do as has been said; pull it back in place with drywall screws. it will have to be done slowly a little at a time. i like to use a piece of plywood/2x8/whatever and jack up the sag with a porch jack and screw it in place while it is pushed up. the placter patching of the cracks is another thing. i've not found anything that will last over 1 year. if you do, let me know.

from reading your other post, it seems as if you have plaster board(16 in wide and maybe 12 ft long). i have the same thing in my house(circa 1948). when it sags, the only way to repair is to do as has been said; pull it back in place with drywall screws. it will have to be done slowly a little at a time. i like to use a piece of plywood/2x8/whatever and jack up the sag with a porch jack and screw it in place while it is pushed up. the placter patching of the cracks is another thing. i've not found anything that will last over 1 year. if you do, let me know.

Good thinking on jacking it up first. I'll have to devise a plan for that. Yeah, isn't plaster "charming"? haha. Love the cracks. I wonder if there is a roll-able white silicone that we can paint the house with? :-)

I'm guessing definite pilot holes here, correct? The wood in my house is rock hard, and I'll need almost a concrete bit to drill through the ceiling. :rolleyes: Did you have any trouble with the drywall screws breaking through the plaster-coat when they were sucked up? I've been afraid of the v-shaped bottoms but like the idea of the flat-head screws..

Thanks,

Gina

Look again. Is the plaster sagging between the joists? If so I don't think you can suck the ceiling up unless you give yourself something to screw to which is probably not as easy as replacing the ceiling.

What is the spacing of the joists? If they are 24" oc they could be sagging between. I've seen this in some tract homes of a vintage to have plaster but where they tried to save a few joists. I have never bothered to try to fix them because I could tell the gypsum lath (one brand is RockLath by USG and it is often used generically for any gypsum lath of the era) was still tight but the sagging was between.

Let us know the spacing of the joists and whether or not the ceiling is wavy indicating it is tight on the joists and sagin in between.

Now all the advice about pushing it up and screwing it with plaster washers or the like is good advice if the problem is other than sagging between the joists.

If this is a small area it can be repaired with new plaster but you are exactly right about the mess if you remove any part of the ceiling.

If it looks like there could at all be a future hazard, you can simply overlay sheetrock it. We have done that a lot in rentals.

Ever feel what just a 1 foot square chunk of plaster feels like for weight? You sure wouldn't want that coming down on your face or juggler vein at night while you sleep!

In a rental some years back, this college kid was sitting there in his easy chair when - "THWUMP"! This huge chunk fell off the ceiling and came crashing thru the drop ceiling, near him. You can imagine the almost heart stopping shock of this.

In old plaster houses where the ceiling is sagging badly, I ALWAYS recommend demoing out and replacing with 1/2 inch sheetrock.

I've had experiences where a homeowner was hesitant to replace because of mess/cost/time involved but after the bedroom ceiling collapsed onto her bed while she was at the market, she quickly changed her tune.

I prefer to do the demo and replace with fresh sheetrock rather than just rock over because when you just rock over it you are adding a lot of weight to an already old and failing ceiling. Just asking for trouble in my opinion.

In the end if you do it right once, you'll never have to mess with it again. If you want to do it the quickest, easiest, cleanest way you are going to have a much bigger problem to deal with in the future.


Good luck,
Nicholas J. Faustino

They might of nailed the lathe in the same direction as the joists resulting in it sagging.
If it is then there will be nothing inbetween the joists to screw too anyways.

I would check along the long runs where the sag starts to see if they did.

If it is very bad and falling down, I would take it out and replace with drywall. If its not going to fall down, mesh the hollows and fill them in with compound. Use a long 14-16'' trowel. It wont sag anymore through time.

I haven't tried this mind you but I bet someone has and can tell us how it works.
Most of the mess of demolating a ceiling is the insulation. With plaster especially plaster in this condition it should come off in great chunks. So before you take any plaster off why not put on a good respirator and go into the attic with an electric leaf blower and move the insulation well away from the room involved then cover the floor,tape the door and let the insulation settle and pull off the ceiling. Now if the joists are 24" o.c. use 5/8 rock to replace it. I guess while the ceiling is down one could install batt insulation before the new rock too. The excess that you blew away will settle somewhere where it will probably do some good and add enough weight to make the ceiling in another room sag too. Then once one room is taped use the same process on the next room and the next.

How does this sound for a plan?

I have been repairing plaster ceilings for years and I have gone over crooked plaster with drywall several times. I have worried about the excess weight on the joists and If this ceiling is as bad as I picture it and I have seen plenty of ceilings like this I don't think new rock will pull the sags out and all you will have is another crooked ceiling.

But as I said most of the mess is the insulation and it will go everywhere in the house but if you can keep it in the attic and away from the ceiling in question it will be much less mess.

Good thinking on jacking it up first. I'll have to devise a plan for that. Yeah, isn't plaster "charming"? haha. Love the cracks. I wonder if there is a roll-able white silicone that we can paint the house with? :-)

I'm guessing definite pilot holes here, correct? The wood in my house is rock hard, and I'll need almost a concrete bit to drill through the ceiling. :rolleyes: Did you have any trouble with the drywall screws breaking through the plaster-coat when they were sucked up? I've been afraid of the v-shaped bottoms but like the idea of the flat-head screws..

Thanks,

Gina

been away from the computer a while. no! if the ceiling is jacked back up, and the screws are not pulled through, they usually hold fine. i do use more screws than normal because of the weight and the plaster. however; as stated, if the ceiling is sagging badly, and is on plaster lathe as opposed to plaster board, the the very best was is to remove and replace with drywall. that will end that problem. it does, as also stated, create the problem of insulation above that will have to be dealt with, especially if the plaster is on 24" center joists. using a pilot drill is a really good idea. the advise i gave was on the premise that it was an isolated spot and not subject to falling at this time. i have also just put drywall over the plaster, but only in small rooms. it does add a lot of weight and you still have to jack it up and use longer screws. there is really NOT a GOOD way to patch this if it is a larger area. think about the drywall replacement if you plan on being there a while

Well, I tried the screws. They stuck, but the ceiling there still looks wavy. I'm not sure what to think. How can I tell if the rock is laid parallel to the joists or across them? Can I dig around in the attic for this? To be honest, I've only been in the side attics, I've never even been in the top one... :o I think my dad went up there when we were blowing insulation so I managed to skip out on the whole deal... about 15 years ago.

The whole ceiling isn't sagging, but I have cracks to repair. Joists seem to be on 16" centers. Most of the cracks have been patched before, and they are going perpendicular to the joists. This one place in particular is going from the long crack in the center (where the light fixture is, same in the other room, perpendicular to the joists) and then taking a 90 and going parallel to the joists for 2-3 feet. This is where I can gently push on the ceiling and see it move. I think it looks worse than it is - possibly from the original plaster job, or the times it's been patched previously. This new crack running along the joist (I was able to hit it with the screws) has not been patched before.

I also have one of the short walls that has a stair-step type crack in it, spanning 3 sets of studs. It doesn't concern me as much because it's the wall, but something must've shifted since I originally painted everything stark white in '93. I'm planning to V that out and durabond it and hope for the best.

I just dread demoing the ceiling though. I absolutely hate working on ceilings. Since it's just in that one area, I don't think there is any reason to think the whole deal is going to collapse. It's not sagging like I've seen wood lath ceilings do. It's one of these deals where I want to do it right, yet I don't really want to rip it all out and start over. :confused:

Paint is ready, rag-rolling stuff is ready, new light fixture ready, new bed ready... but I need to patch the stupid ceiling first. Are there some danger signs here; what can I tell from hiking my butt into the attic?

:rolleyes: Gina

Can you put up some pictures that show the sags and cracks?
I think the cracks are following the joints in the gypsum lath. that could probably have been prevented before plasterirng with some chicken wire reinforcing or metal lath strips over the long joints in the gypsum lath. But that wasn't done so now you have cracks. You still haven't made clear to me if the sags are between the joists hence the waviness or on the joists, hence the cracks

What part of the country are you in?
Is there good ventilation in the attic?
What kind of insulation did you blow in and how much?
Did the sagging show up after the insulation?
If you laid an 8' long straight edge over the ceiling how much difference in height would there be between the places where the straight edge touched and the greatest gap? Is the gap over the joist?

I think you are going to have to replace the ceiling.
The consideration you have is that if the plaster falls, which frankly is possible but not likely since you have gypsum lath. both the lath and plaster will fall and the insulation will come down too. If it were wood lath probably only the plaster would fall and much, maybe most of the insulation would still be captured above the lath.

Has anyone tried my idea of using an electric leaf blower to clear out the insulation in an area before demolating a ceiling?

I've seen a lot of this in ceilings in my part of the world when they were plastered over gypsum lath on 24" oc joists. Putting more material up there whether it be new sheetrock or more plaster even if it's Structolite is the additional load on the joists.

I think if you do this right it will be to remove it. Not to do it right will mean doing it the rest of your life. Which will probably be shorter because you will work yourself to death.