On Nov 8, 6:56*am, zek wrote:
On Nov 7, 10:51*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,

Fiberglass over cellulose, *really dumb.
If you added spray foam to the roof, condensation is not a problem if
its done right, and you
would seal ALL holes. A good thermal break will not create any
condensation problems.
You could add more cellulose, and add a reflective coating or cover
for
the rafters that keep reflective heat in and summer heat out. A cover
being perforated alumina sheeting.- Hide quoted text -

- Show quoted text -

Spray foam on the roof is about as dumb an idea as has come along.

His attic space is vented so you block that off. Great, now you hae
made the entire attic part of the heated portion of the house before
the insulation takes effect.

When insulatomg you put it where it will do the most good. That is on
the floor of the attic and needs to cover a lot less square footage of
area.

Curious. Why is fiberglass over cellulose a bad idea? I'm still
trying tofigure a way to do the old half of this house, only access is
thru a 2x2' hatch and I don't want the blown in due to the mess.

Harry K