I am thinking about using blown in cellulose insulation for new
construction: walls, attic as well in floors between first and second
floor and between first floor and basement. I have a lot of pipes and
wires so I suspect blown in cellulose will provide better value then
fiberglass batts which hard to put around so many obstacles.
Has anyone done this?
What's the cost of blown in cellulose vs fiber glass batts?
What's the best way to apply it to walls and floors? I saw video when
they blow it to wall open cavity then use some sort of screed to
screed excess flush with walls. What about floors? If I blow it to
ceiling will it stick and not fall down?
I heard most places who cell cellulose insulation rent the blower for
free. Does HD or Lowes rent it? Can one man operate it?
Not cellulose. The stuff you see squirted into an open wall is polystyrene
foam (think Great Stuff).
Sprayed foam has superb insulating qualities (R=6+/inch) and not cheap.
Fiberglass is about 2/3rds (R=4/inch) the insulating qualities of foam.
Cellulose has about the same R-value as fiberglass, but is typically applied
in a thinner layer resulting in an overall lesser R-value than fiberglass.
You can't easily use blown-in cellulose on a wall. To do so, you have to
finish the wall, open a hole, fill the cavity, then patch the hole. One hole
per stud. After that, the cellulose will settle with time and you'll end up
with only 3/4 of the wall insulated.
In your case, I'd recommend fiberglass batts and a sharp knife to mold it
around pipes and wires.
Actually, they do indeed do cellulose based blow in insulation in open
wall cavities and screed off the excess flush with the studs. The
cellulose is I think lightly dampened for application and I suspect has
some light tack binder added. At any rate from what I've seen it works
well and should be much easier to fish wires through later if needed
than the spray foam or fiberglass batt insulation. For new construction
I still recommend installing strategically placed conduit since 3/4" PVC
conduit is very inexpensive and installing it in new construction will
take all of one evening and cost $20 or so.
Why do you need conduit? To hold blown in insulation in place? I
thought for this purpose to staple PE sheathing (which needs to be
done anyway for exterior walls) and then blow insulattion through
holes in each cavity.
No, he is right - spray cellulose IS used - a LOT in some areas.
Polystyrene foam is NOT sprayed in place. Urethane foam is.
Personally I don't like the cellulose, and prefer the urethane foam.
There is standard wet applied cellulose, and stabilized cellulose -
both of which seal quite well and do not suffer from settling - as
long as they stay dry after application. Both require a minimum of 24
- preferably 48 hours drying time before covering with wallboard.
Stabilized cellulose is generally used in ceilings and on the bottom
He is NOT talking old school blown in, or "loose fill" cellulose.
This stuff goes in wet and sets up like a combination of felt and
That works too - but does not seal air or sound as well as spray
cellulose - which does not work as well as spray urethane foam for the
same job, but costs less and is easier to remove if required for
Since all the walls are open, I'd price pro-applied spray foam as well.
Superior insulation, and it acts as its own vapor barrier. Probably
higher up front cost, but quick payback in heat/cooling costs. But why
insulate above basement, unless it is gonna be finished living space and
you are looking for sound deadening?
When i had my 1400 sq. ft house done it was about 20% higher for the
entire job, done by the pros, than what the material alone would have
cost me to do fiberglass myself. It's NOT that much higher. A dollar a
square foot for 12" of it in the attic and .75Cents a square foot for
wet sprayed 3.5" walls.
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When I was running the numbers a few years ago, dense pack cellulose in the
walls and pro pink blown loose fiberglass in the ceiling ran about 25% more than
what batts would have cost. The cellulose has superior insulation, air
infiltration and noise reduction properties, so that was worth it to me.
Sprayed open cell foam was about 3x the cost of batts. Would have loved to get
it, but couldn't make the numbers work. I did buy Tigerfoam and did the
underfloor in one corner of the house later. The guys who do this for a living
earn their money, believe me. Working with that stuff in a crawl space is not
There is a newer hybrid approach where you foam the wall cavity first with a
very thin coat, then fill the rest of the space with fiberglass batts. Gives you
the airseal of foam and some R value but reduces the material cost at the
tradeoff of the extra labor to install.
I've done it several times. For the walls you'll want a wet sprayed
application before the wall board goes on. You'll need to have that
professionally done. As for the attic, you can blow it your self, but
it'll take 10 times as long as the pro guy. And a foot of it up there
should only run you about a dollar a square foot. As for the wet spray,
the last i paid was 75 cents a square foot for 3.5" walls. It's well
worth the money if you can't afford closed cell foam. I'd use the
cellulose in the attic even if I did foam the walls.
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