Subscribe or Renew Membership Subscribe Renew

Insulation on 1/4 inch drywall

michaeldrehl's picture

Hi, I have a house that had plaster and lath ceiling. There was another ceiling created with 1/4 inch drywall and 2x4 screwed in the wall. There is a feet of space between the plaster ceiling and drywall. I wanted to place or slide fiberglass insulation in the ceiling from the top in attic space. From the attic, I see that the plaster has large gaps and wholes. I would cut a linear opening in the plaster and slide the insulation. My worry is that since it is a 1/4 inch drywall, the fiberglass insulation will cause it to sag. 

I'm thinking of using R-13 batts. To lower the weight, I was thinking of ripping half of fiberglass off. Even with lower and half of the  R-Value, at least there would be some insulation than nothing. 

Any thoughts?

Thank you for your help.

Best advice. (post #216203, reply #1 of 9)

Get rid of the drywall ceiling. Repair the plaster. Insulate above.

Second best advice. Insulate above the plaster. 

1/4 drywall will sag under its own weight if it hasn't already. 

 

Mike

? (post #216203, reply #3 of 9)

.

It's very unusal to use 1/4 (post #216203, reply #2 of 9)

It's very unusal to use 1/4 inch drywall. Mostly it's used when laminating over en existing surface or as  two layers when you need a curved surface. Are you sure its 14 inch and not 1/2 ? 

If you trust the framing you could go over the 1/4 inch with 1/2 inch drywall. I would not suggest trying to snake in batts of finsualtion through the hoels you willnot get 100% coverage. Rather try blown in cellulose or spray foam.

My mistake. It's actually 3/8 (post #216203, reply #4 of 9)

My mistake. It's actually 3/8 inch drywall ceiling. 

Can I still cut and insulate above the Sheetrock? Or it needs to be 1/2 inch?

It will never work. In spite (post #216203, reply #5 of 9)

It will never work. In spite of what everyone thinks fiberglass is very hard to install so that it actually works. It's very fussy work that demands a perfect fit everwhere or you will be throwing your money away. There is no way you can cram it in a small space, poke it around with stick and do a good job. Small voids will cancel out any insulation factor you could achieve.

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

Thank you for your input. But (post #216203, reply #6 of 9)

Thank you for your input. But will the insulation cause the 3/8 inch drywall to sag? or the drywall needs to be 1/2 inch?

3/8'? (post #216203, reply #7 of 9)

How far apart are the supports? Sometimes even 1/2" will sag with 24" 0.c.

.

The wooden 2x4s are about 14 (post #216203, reply #8 of 9)

The wooden 2x4s are about 14 inches apart. 

If you push insulation into (post #216203, reply #9 of 9)

If you push insulation into the space the 3/8' drywall will develop lumps and bumps.

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.