I'm in a house that's new (to me), and it's downright chilly. The house
could use (but doesn't necessarily need) new siding, which would provide an
opportunity to install those sheets of insulation underneath. I don't like
the siding color, so this would achieve two purposes. But, this year, the
budget would not allow for both siding, and blown-in insulation. Anyone know
how the two methods (exterior sheets vs blown-in) compare, in terms of
slowing heat loss?
I would think that if you are going to drill holes in the outside walls
to blow in insulation that the time to do it is when you are doing the
siding. Wait till next year if you have to.
More importly, why is your house so chilly? Could there be another
reason like inadequate attic insulation or drafts? My reasoning being
that my house has no wall insulation (bricks -> cinderblocks ->
plaster), but I have an attic full of insulation and double pane
windows and no drafts, and it's really OK like that.
All windows except two have storms, and tight ones, but with only an inch
between the panes. There's a large on in the living room that's single pane,
and another in the kitchen. I've put plastic on them for now, almost 6" in
from the glass. The attic's got 12" of the pink stuff. I've been gradually
prying open outlets and other access points, but I still can't get a sense
of how much insulation's in the walls. Doors are tight.
This one is easy - get the R value of whatever particular product you are
looking at. Sheets will generally be much less than blown in insulation.
As another poster mentioned, it will likely be a world easier to blow it in
from the outside, where you can just cork the hole and put siding over it -
vs redoing perhaps 1-200 holes all over inside the house in your sheetrock.
I have 1/2" insulation under steel siding, with no insulation in the walls.
The siding thing helps, but there is still a definite temperature gradient
you can feel inside the house in the hottest of summer and coldest of winter
days. I have ceiling fans in every room now as well as a whole house fan,
which made a big difference in overall comfort. Colorado. I'll likely
never blow anything into the walls. Sounds like an epic. I have trouble
seeing how it would pay off in less than 10-15 years.
1/2' white foamboard is R 1.75 The pink it is R2.5 for 1/2" . Blown
in at 3.5 inches will be alot better. But what will you use Cellulose ?
It can make your house a mess with future dust. Icynene foam would be
the way to go 3.5" of foam would be R 12.25
Cellulose would be my choice as it is 1/3 the cost of the rigid sheets but I
also plan on airsealing every crack to eliminate any dust or air
BTW, if you are in Canada the government will provide a grant based on the
difference pre/post retrofit energy improvements done to your home. I just
had my 'pre' test done and have the potential to go from a energuide rating
of 37 to 77 which will result in a rebate of $2100.
Depends on what your siding is. Mine was wood which I removed,
removed 50 year old tarpaper, put in 4" insulation and recovered house
in tyveck then put wood back up then vinyl. Lots of work (mostly for
my 15 year old son) and done in sections.
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