On Nov 7, 9:51*pm, BARG wrote:
My old house needs some insulating, and I've been looking at the
companies that do spray foam.
I'm in the Midwest, in Chicago, where winters can get very cold.
I have an unfinished attic space over one half of the house, and then
a room with knee walls and a much steeper pitched roof on the other
side.

One company proposed removing the existing blown cellulose in the
unfinished attic, and then spraying the roof joists to insulate that
space. *I'm not keen on the idea of the roof not being able to
"breathe", and also, I have roof vents, so the roof will be insulated,
but there are still big holes in the roof! *This seems dumb to me. *Am
I missing something here?
I do have some of the HVAC duct work in that attic, so my impression
is that it might be most helpful to find a way to insulate the floor
of that attic AND create some sort of insulated capsule over the main
metal trunk up there. *The ducts to the ceiling vents are flexible
foil-like ones.

Another company proposed simply blowing loose FIBERGLASS over the
cellulose. *I suppose that would be okay, but what a mess.

opinions? *ideas?

(I'll probably post separately for the other room, and I also have a
basement that needs insulation!)

thanks,

Do you mean you have insulation on the attic floor now and a guy wants
to remove it and spray the underside of the roof with foam, and your
attic is open, vented for fresh air? If so it wont do anything and you
will be colder. How thick is what you have now, I think you can figure
3.75R per inch of cellulose for what you have now. R 35 is minimum
code but I would go to R 60 or so. With an open attic as it gets below
20 fiberglass looses R value, maybe up to 25% as it goes below 0. I
dont know if cellulose does this also but its the cheapest way to go,
but add an extra maybe 10-15% foor settling. I think you need some
more bids from real pros and do your research first. I dont think you
can foam over cellulose, it will make a vapor barrier and mold and rot
the cellulose and maybe more, especialy if you humidify