Blown in cellulose in new construction

[ls02]

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?

[HeyBub]

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.

[Pete C.]

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.

[Tony Hwang]

Hi, Moisture is biggest enemy of that and wall? it will settle over time.

[HeyBub]

I saw that, but the "dampened" cellulose takes up to a YEAR to dry...

Good idea about the PVC "conduit" (a regular hunk of PVC should work).

[aemeijers]

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?

[clare]

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 of roofs.

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 papier mache.

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 renovations/repairs/other access.

[clare]

You are not talking about spray cellulose - you are talking blown loose-fill. TOTALLY different process.

[clare]

Most common reason for insulating floors, period.

[Steve Barker]

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.

[Steve Barker]

mostly mis-information in this reply.

[Steve Barker]

About a week actually. Less if the a/c is running.

[Steve Barker]

Wet sprayed cellulose does not settle. Stabilized loose fill (in attics) does not either.

[Robert Neville]

Had this done? Yep. Highly recommended over fiberglass batts. Higher R-value for a given depth, much less air filtration, and excellent noise control.

Maybe 25% more than what batts would have cost.

You don't want to do this yourself. It takes a pro to avoid a crap job or leave voids around pipes and electrical cables. Too dry and you'll lose anything you spray, too wet and you'll create a mold problem.

Those DIY blowers work OK for attic jobs with dry material, but don't do anything close to the pressure needed for damp material in the walls.

[Robert Neville]

If it takes a year to dry, it was applied far too wet. When I had it done to my last house, it was completely dry before the drywall went up 3 days later.

[Robert Neville]

No probably about it. When I ran the numbers it was about 3X the price of batts and the payback even over cellulose was over 10 years. The numbers don't work for most locations.

[ls02]

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.

[Steve Barker]

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.

[clare]

Condoit allows changing or adding wires in fully insulated walls. A lot easier than oking wires through a "stuffed" wall cavity - which is hard enough in batt insulated walls.

[aemeijers]

I was talking about foam, not cellulose.