On Apr 28, 7:08*pm, dpb wrote:
Una wrote:

...

The roofer proposes to strip this stuff off completely, put on a 4 inch
insulation, put a 1/2 inch plywood or OSB decking on top of that, then
felt and shingle.

Sounds like good plan to me -- the celotex is probably still fine except
for the places it is obviously not, but it is of marginal R value (I
don't know the numbers ottomh, but it wasn't really an insulating
product but an inexpensive sheathing product).

Consequently, what the roofer is proposing will probably save more in
heating/cooling costs in a relatively short time than the expense.

--

Unheated attics are to be insulated at the floor, unless I missed
something