Ceiling – How to repair the cracks in the ceiling before painting
ceilingrepainting
I want to repaint my ceiling, but I can’t quite tell what’s going on. Is there a layer of drywall? Plaster?
What should I do if I just want to repaint?
Best Answer
You have two main issues: 1) crack length of room, and 2) top coat and brown coat separating from scratch coat.
1) When we see cracks running in the middle of a room, it’s usually from undersized ceiling framing. Lumber bends most at the center of a span. If the lumber is undersized, it will deflect excessively and thus cause a crack in brittle materials like: plaster, ceramic tile, etc. You’ll probably need to sister an additional joist next to the existing joists.)
Before you fix the crack and paint, I’d suggest you verify the ceiling framing is adequate. (There are span tables on the internet that can tell you what size lumber should be used to carry the existing plaster plus any additional plaster (or gypsum board) repairs...or you can ask on this forum giving span, spacing of existing joists, any loads above ceiling, etc.)
2) Plaster is generally a 3 step process. Each layer requires the new layer to bond to the previous layer. Looking at the missing piece, it appears the plaster separating is about 3/8” to 1/2” thick. That means the brown coat (about 3/8” thick) and finish coat (about 1/8” thick) is separating from the scratch coat.
There is no easy way to repair this problem without removing the brown coat and finish coat. (You can’t just nail it back up because it’ll continue cracking and separating and it will be very uneven.)
Often people choose to remove the worst areas and then install gypsum board over the entire ceiling. However, that adds a great deal of load, but you may need to reinforce the existing ceiling joists anyway.
The point of Green Glue is to create a flexible layer of never fully firm glue between layers of drywall, right? To absorb sound?
In which case, I think you'll need to first level the ceiling, then apply green glue, then apply your final layer.
Otherwise, if you green glue over top of the texture, you'll have high points in the texture that touch the new layer of drywall. That will transfer sound quite effectively - which you don't want.
The fact that sections are peeling off indicates that there is a structural problem with the overall "sandwich."
In any repair, unless you can overcome the structural deficiencies with an overriding mechanism, you have to strip back the unsound sections until you get to good structure. With you description , it is hard to see where that is.
You could knock loose all the compromised sections and then try to patch the open areas, but it sounds like the overall lathe-plaster-chicken wire-plaster amalgam may be questionable. You may do this and shortly thereafter find a new section that is failing.
I think that a drywall overlay may be the simplist, fastest and cheapest solution, by far. Whether you strip down to the chicken wire or to the lathe depends on how much of the ceiling is loose/compromised. If height is not a problem, dislodge whatever is loose, use shim to insure level and then screw up thin drywall over the whole ceiling. DO NOT USE NAILS! If you hit studs, great, but the lathe should be adequate to hold a thin wallboard lamination.
Best Answer
You have two main issues: 1) crack length of room, and 2) top coat and brown coat separating from scratch coat.
1) When we see cracks running in the middle of a room, it’s usually from undersized ceiling framing. Lumber bends most at the center of a span. If the lumber is undersized, it will deflect excessively and thus cause a crack in brittle materials like: plaster, ceramic tile, etc. You’ll probably need to sister an additional joist next to the existing joists.)
Before you fix the crack and paint, I’d suggest you verify the ceiling framing is adequate. (There are span tables on the internet that can tell you what size lumber should be used to carry the existing plaster plus any additional plaster (or gypsum board) repairs...or you can ask on this forum giving span, spacing of existing joists, any loads above ceiling, etc.)
2) Plaster is generally a 3 step process. Each layer requires the new layer to bond to the previous layer. Looking at the missing piece, it appears the plaster separating is about 3/8” to 1/2” thick. That means the brown coat (about 3/8” thick) and finish coat (about 1/8” thick) is separating from the scratch coat.
There is no easy way to repair this problem without removing the brown coat and finish coat. (You can’t just nail it back up because it’ll continue cracking and separating and it will be very uneven.)
Often people choose to remove the worst areas and then install gypsum board over the entire ceiling. However, that adds a great deal of load, but you may need to reinforce the existing ceiling joists anyway.