Is there a good method for insulating a ceiling with strapping?
I am in the process of removing a bathroom ceiling due to a large crack that spans the entire room.
I am going to reinstall a new ceiling using 1×3 strapping because I believe the current ceiling failed due to either joist flexure or the crown of the joist is facing the wrong direction. I believe by strapping and shimming this should protect the new ceiling from failing in the same manner.
The ceiling is adjacent to the attic above and therefore needs insulation . For simplicity I was going to use fiberglass batts with kraft paper and staple the kraft paper to the joist faces.I understand the insulation must come in contact with the backside of the drywall in order to be most effective. However, the strapping will not allow it to do this due to a 3/4″ air gap caused by the thickness of the strapping. From reading some people had mentioned blown in insulation for situations like this, however the area that needs to be insulated is very small (5′ x 9′) and I feel that renting a machine just to blow in insulation above this area seems to be not worth the trouble.
A couple of ideas I had:
Install 3/4″ thick foam insulation boards between the strapping from the bathroom side then place unfaced batts on top of foam board in between the joists in the attic. I am not sure how this works with the vapor barrier. Would I need to add a plastic vapor barrier or does the foam provide a good enough barrier? Also, would there be any negative effects of layering two different types of insulation materials on top of each other?
Spray foam in all the cavities until the 3/4″ in thickness is filled and lay fiberglass batts on top. Same concerns as above.
Pull apart the fiberglass batts and fill the 3/4″ spaces with this material leave the kraft paper and staple this to the strapping. Apply unfaced fiberglass on top of this layer in the attic. I would think this would be the most time consuming due to the amount of cutting required to make the 3/4″ thick batts, however it would be the same material layered on top of each other.
Leave 3/4″ space open.
Do any of these ideas sound viable? Or is there another method that would work better?
On a side note. I have seen a lot of debate about using a plastic vapor barrier on a bathroom ceiling. Some say this is necessary and much better than kraft faced paper, others say it may cause moisture buildup and eventually mold because the plastic does not allow the moisture to pass through where the kraft paper does.
I appreciate any suggestions and thoughts as I can tend to overthink these things :).
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