[Greenbuilding] Cellulose blowing tools/techniques

[George J. Nesbitt]

Jay is right.
 If you use a hose to fill the cavities it might be hard to consistently 
pack them, and hard to keep the hose in a given cavity unless it is 
ridged (witch it should be). The fabric wouldn't be a thermal bridge. 
Not having filled double walls before with dense pack cellulose I am not 
sure if, or how much of a problem this would be.



George J. Nesbitt wrote:
> 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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