cnelson0131

We removed the drywall ceiling in two rooms due to a roof leak. I would like to know if it is possible to insulate the rafters properly and leave the ceiling open to paint....and not replace the drywall. Thinking of using styrofoam insulation; 10" joists. One roof is a flat roof, the other a slight pitch.

joecaption

Hard to say without being there to see it.
Recommended Levels of Insulation : ENERGY STAR
Not sure why you would want to use blue foam, far more expencive then just fiberglass batts, and more work.
There has to be an air flow from the soffits to the peck of the roof to keep the shingles and sheathing from over heating so you would have to add foam baffles if you insulate. By adding them you will reduce the amount of inslation that will fit uncompressed in the bays.

PS, joist are used to build the floor and ceiling, rafters are what's holding up the roof.

cnelson0131

Can you tell I'm a novice? Thanks for pointing out the difference between joists/rafters.......no one that I've talked to "enlightened" me.....

Since we have to replace a roof in two different areas of our house......we are leaving the inside till later....and focusing on the outside replacement.

Thanks for your input.....hopefully, whoever we find to do the roof, will be able to advise on the interior also.

nealtw

When you have the ceiling drywall and the roof sheeting both attached to the same framing, as in your 2x10s you need to have airflow above the insulation and venting on each end of every bay or strapping going the other way acrose the 2x10s and the required vents for the sq.ft that you have. This is well worth understanding while you have it open and a new roof on the way. Failure to vent properly can cause all kinds of problems.
I know it wasn't part of the question but I thought I would throw it in incase you hadn't looked at venting.