insulation batts, blankets & other ?'s ...

Around here (central Alberta, Canada), the 24" insulation is about as common
as the 16". Don't know about other places, though. Even though the 16"
wide insulation is less per square foot, I went with the 24" wide for the
ceiling, as I was putting up vapor barrier at the same time, and I didn't
figure the two pieces would stay up there long enough for me to tack up the
plastic. In your case, with a finished floor, I don't think it would really
matter, but I'd look at renting an insulation blower, and buying the loose
fill stuff.

--
Clint
"flipper" <[email protected]> wrote in message
news:[email protected]...
> in my garage conversion, i'm laying insulation on the unused attic
> floor; ie, right on the flat plywood flooring, not in b/ joists. i
> can't get insulation blanket around here in r30, so i'm limited to 15"
> and 24" width batts x 48" long. the cost of 15" suits my total-sq-foot
> needs better, so i'd like to get it; but will more seam connections
> with 15" result in less insulating power?
>
> also: around here, neither lowes nor HD stock r13 in the 24" width.
> they don't stock it and say they can't get it. i thought 24" was as
> standard a width as 15". Is that not so?
>
> thanks
>
> ps: cross posted this to one other logical ng.
>

I was looking into insulating the ceiling in my pole barn shop. The
purchase price for the insulation from the local Ace Hardware store was
about $600. I called an insulating company, and got a price of $650 for
insulation installed with a white reflective sheeting over the
insulation.
robo hippy

Check the building codes for your area. The 24" is generally not
available if the local code does not allow 24" framing.

The joints are not a problem if you can keep the bats firmly pressed
against each other.

I would consider throwing a piece of something like tyvek over it to
keep dust out of the insulation and to provide another air barrier.

According to flipper <[email protected]>:
> in my garage conversion, i'm laying insulation on the unused attic
> floor; ie, right on the flat plywood flooring, not in b/ joists. i
> can't get insulation blanket around here in r30, so i'm limited to 15"
> and 24" width batts x 48" long. the cost of 15" suits my total-sq-foot
> needs better, so i'd like to get it; but will more seam connections
> with 15" result in less insulating power?

If you're doing unfaced batts, the seams are irrelevant if you've
installed it properly.

> also: around here, neither lowes nor HD stock r13 in the 24" width.
> they don't stock it and say they can't get it. i thought 24" was as
> standard a width as 15". Is that not so?

R13 is for 2x4 stud walls, and R20 is for 2x6 walls. Building codes
generally do not permit the use of 2x4s on 24" centers, hence, 24"
R13 is a pretty rare size.

You need to base your insulation selection on desired R-value, not
batt width. With unfaced batts, the determining factor in cost
per square foot is R value (thickness) not batt width.

There's probably a reason that insulation manufacturers don't suggest
using building wrap on top of ceiling insulation - it's a bad idea.
Dust in the insulation will not make much of a difference, and you
want to minimize as much as possible any blockage of moisture transfer
_out_ of the insulation.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

flipper Wrote:
> in my garage conversion, i'm laying insulation on the unused attic
> floor; ie, right on the flat plywood flooring, not in b/ joists. i
> can't get insulation blanket around here in r30, so i'm limited to 15"
> and 24" width batts x 48" long. the cost of 15" suits my
> total-sq-foot
> needs better, so i'd like to get it; but will more seam connections
> with 15" result in less insulating power?
>
> also: around here, neither lowes nor HD stock r13 in the 24" width.
> they don't stock it and say they can't get it. i thought 24" was as
> standard a width as 15". Is that not so?
>
> thanks
>
> ps: cross posted this to one other logical ng.




I you are up for it, blown insulation (basically recycled paper) is
about as good as typical insulation gets. Also available as fiberglass
but fg is not as an efficient insulator. Either are fast and easy to
install. In my area Home Depot has a deal going where they would lend
you a free blower (from their tool rental dept) when you bought the
loose insulation from them. The down side of blown insulation will be
discovered if you ever have to remove it. HD also has a rebate going,
I think $75 per $1000 of fiberglass (rolled?) insulation. Owens
Corning’s website has an insulation calculator, enter your zip code for
recommendations on the R factor and type of rolled fiberglass insulation
for your area. See other websites regarding the
advantages/disadvantages of blown insulation.

http://www.owenscorning.com

Yes, 24-in width is a std roll width in my area.


--
joe2

[email protected] wrote:

> Check the building codes for your area. The 24" is generally not
> available if the local code does not allow 24" framing.
>
> The joints are not a problem if you can keep the bats firmly pressed
> against each other.
>
> I would consider throwing a piece of something like tyvek over it to
> keep dust out of the insulation and to provide another air barrier.
>


++++++++++++

Interesting I guess I never thought of laying tyvek over the top
of the pink stuff. Seems like it could trap moisture? Does dust
hurt the insulation? Why doesn’t any of the insulation
manufactures suggest doing this? I have a half a roll of Lowes
house barrier leftover, maybe I’ll unroll it in my attic…

TP