[Greenbuilding] Cellulose blowing tools/techniques

[George J. Nesbitt]

Insulating open stud walls with cellulose.
There are many ways you can do this.
    1. wet spray, not a do it yourself job for most. You need equipment 
beyond just the blower that will cost $1000+/-, and you aren't likely to 
rent. This is best left to "professional" crews and equipment. Don't use 
cellulose with ammonium sulfate, you get  ammonia gas when you add  
water. It is also corrosive to metal (truss connections). Use a borate 
only formula. Some cellulose comes with glue in it, and others you have 
to add with pumps and sprayers. The problem with the glue, wheat, I am 
allergic to gluten (in wheat and many other glues). Cocoon has 3 
formula's, none of them good for me. Cocoon 1,black bag, loose fill, 
ammonium sulfate. Cocoon 2, green bag, stabilized, ammonium sulfate and 
wheat glue. Cocoon 2, blue bag, stabilized borate formula, wheat glue.
    2. Dry spray, Home Energy had an article in the May/June issue on 
these methods, better for the small insulation contractor or do it 
yourself.
    A. Glue and staple fabric to walls, insert fill tube, fill to 
3.5lbs/cuft or greater, use roller to flatten insulation. The glue 
prevents the insulation from getting between the fabric and the stud 
which would interfere with the drywall. I don't recommend poly, we don't 
want a vapor barrier where it can be a condensing surface (inside or 
outside surfaces). The fill tube (as Bob said) allows you to fill at a 
consistent high density. The roller will flatten the insulation so it 
doesn't stick out and hold up the drywall. I have not tried this method 
yet, batts would still be easier and less expensive to install, although 
not quite as good in performance.
    B. You can temporarily screw drywall, foam, or any other rigid board 
product on the walls and use it as a form for blowing. This might be 
more work than using fabric. This would allow the inspector to see the 
insulation before you drywall. I have not used this method.
    C. If you drywall, or have existing cavities, there are several ways 
you can do this.
    C.1. Drill 2" to 2-1/2" holes in each bay, insert fill tube, and 
fill (as bob said). I do this all the time (ok, when I can). You need a 
powerful blower, more so than you can probably rent (especially from the 
home despit), and blowers are not common rental yard equipment (they are 
similar to the home despit machines usually). My 20+ yr old Force 2 
blower can get to 3.2lbs/cuft, ok, but I would like to get closer to 4lbs.
    C.2. I have a HVAC contractor who insulated his house by himself. He 
drilled 4" holes, filled the cavity, and used his hands to pack the 
insulation, filled more, and packed until full. I have done this with 
roof/ceilings, but not walls.
    Material coverage, you can't use the coverage chart for attic loose 
fill, to low a density, 1.6lbs/cuft +/-, you need 2 to 2-1/2 times as 
much. Multiply the sf of walls by .75 (9.5"), then subtract for the 
framing (plates, studs, blocking) and multiply by 4lbs, this will give 
you the weight you need and then divide by weight per bag, and you will 
get the number of bags.
    The only (west coast) manufacturer that I know of of Borate only 
cellulose is in Idaho, truckloads only (600 bags?), but then again you 
might need that at 9.5" thick walls at 4lbs/cuft plus the roof.



Jefro wrote:
> I have been following this thread with grave interest, as I am in the 
> same position---about 3 or 4 weeks away from installing cellulose into 
> my 2x10 wall cavities.
>
> As I see it, I have three options if I want to do the job myself---and 
> given the financial realities of house building, I will be doing it 
> myself.  I'll be using Cocoon cellulose, which is manufactured about 150 
> miles from home, and installing with a rented blower.  This will be a 
> dry install.  Options are:
>
> - sheetrock first, drill holes and install as a retrofit per manuf. 
> instructions
> - install poly netting and blow through it, and hope for the best
> - sheetrock the lower half of the wall, fill with cellulose, then do the 
> same with the upper half
>
> I can see advantages and disadvantages to each method.  Will probably do 
> a test run using each method on a couple of different wall sections 
> first, to see which goes fastest and which seems to fit most densely and 
> thoroughly.  I'll also do a "settle test" by drilling holes at the 
> ceiling in a couple of months and topping off where necessary.
>
> For the third method, I wonder if it would be advantageous to forego the 
> blower, just sheetrock up 4 feet and dump the stuff into the well, and 
> then compress or tamp down by hand before adding the top layer.  Any 
> thoughts?
>
> BTW, I estimated about 105 "bags" of insulation per the manufacturer's 
> recommended coverage.  (They list for horizontal blowing, mine is inside 
> vertical walls so I added 10%.)  The hardware store rents the blower for 
> free if you buy enough insulation.  That means that ALL of the wall 
> insulation to fill 2x10 walls in a 1600sf two-story house for approx. 
> R29 walls, will cost about $1100.  That beats fiberglass by a long, long 
> margin, though of course doesn't count the roof. 
>
>
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