# Attachment strategies for Rigid foam board over plaster ceiling



## frtools (Jun 3, 2012)

Since I have limited ability to add insulation in my attic and cracked plaster ceilings (no serious damage), I would like to recover it with a 1" layer of foam insulation, 1/2" greenboard and a skim coat of plaster. I plan on securing the foam with 1-1/4" insulation washers from McFeeley's and 3" screws. On top of that I will secure the gypsum with 3-1/2" screws. I do not want to build out the ceiling with strapping because of space concerns. Any advice on screw spacing for each layer from those with experience in securing drywall directly over rigid foam. Also any strategies to avoid hitting washers on foam layer when applying drywall.


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## Fix'n it (Mar 12, 2012)

can you get into the attic at all ?
are the ceilings bowed/sagging ?


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## Gary in WA (Mar 11, 2009)

Why greenboard (moisture resistant) rather than "lightweight" 1/2" drywall that spans 24"? Why not remove the plaster and lath, that weighs 8# per square foot plus insulation weight, plus weight of new drywall; you would probably overload the ceiling joists that may be over-spanned if typical in many older houses...

Gary


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## joecaption (Nov 30, 2011)

All that plus why in the world would you want to go over all that with plaster?


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## PoleCat (Sep 2, 2009)

When I did mine I removed all of the plaster and lath. Installed roll insulation from my ladder rather than going into the attic. R-30 perpendicular to and on top of the joists and R-13 in between. Then I installed the foam board and the drywall together. Drywall jack was essential.


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## frtools (Jun 3, 2012)

1) Attic is wide open with original tongue and groove flooring that I do not want to remove. There is already blown insulation under the floow
2) Sorry, I meant blueboard, not green board, blue board is the proper type of board to use under a veneer coat of plaster
3) Not worried about weight and not interested in demoing ceiling to remove perfectly good insulation
4) This method was done by previous owners in other rooms and has produced good results.


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