[Greenbuilding] [BULK] Re: Cellulose settling/blowing

Thu Jul 27 19:19:33 CDT 2006

Lawrence (no, I'm not George, sorry),

I don't understand: are you trying to loose-fill a cathedral ceiling? 
What keeps the cellulose from just tumbling down into a big pile, and 
leaving the peak uninsulated? I must be missing something. What pitch 
cathedral?

Keith

Lawrence Lile wrote:
> George, 
>
> Wow, you've been around a bag of cellulose a few times! 
>
> Here is an installation problem:  I have a cathedral ceiling, 24" deep
> roof truses, and ventilation planned for above the insulation layer.  My
> installer proposes to have the sheetrock installed except for a 12" gap
> at one end of the ceiling, and cover that with a net, then blow
> cellulose into the space from one end.  I'd like to have about 14" of
> cellulose when I am done. Does that sound reasonable? So you can't dense
> pack it, because the space is too deep.  It is bound to settle, because
> it isn't dense packed.  How will they know if they are applying the
> right depth of insulation?  
>
> --Lawrence 
>
>
>
>
> -----Original Message-----
> From: greenbuilding-bounces at listserv.repp.org
> [mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of George J.
> Nesbitt
> Sent: Thursday, July 27, 2006 1:59 PM
> To: Greenbuilder list; George J. Nesbitt
> Subject: [BULK] Re: [Greenbuilding] Cellulose settling/blowing
> Importance: Low
>
> So as a "Professional" installer of cellulose I have the following to
> say about cellulose settling.
>
> If you look at a bag of loose fill insulation (Cocoon) for attic
> installation you would blow it in at 1.4 lbs/cuft density to a depth of
> 12" to achieve R-40, and it would settle out to 10.8". Settling is not
> an issue for attic insulation as long as your final thickness is the
> minimum (otherwise you blew it at too low of density and didn't achieve
> your R-value).
>
> For wall installation you install it at 2.6 lbs/cuft, R-13 with 2x4,
> R-19 with 2x6 (retrofit Cocoon dry pack installation). If you follow the
> manufactures specifications for walls you will get settling. Typically
> (hopefully) this is installed using 1-1/2" holes not more that 4' apart
> (vertically) in every stud bay, and the nosel is stuck into the hole and
> the wall is filled. You might not get around every obstruction and the
> density will be greatest near the hole. I have opened walls (on my
> parents house that I had filled by a subcontractor 10 years before) and
> found a large gap at the tops of the stud bays (holes at bottom of wall)
> either from settling, or not fully filled. When you have a gap in
> insulation it has an effect far greater than its area. So a 1 or 2% gap
> reduced the insulation value 15% or so.
>
> There are two reasons for dense pack cellulose, 1st is to eliminate
> settings, 2nd to reduce air infiltration. Dense pack requires that you
> install at 3.5 lbs/cuft or greater density (I have read that 3.2 is ok,
> but probably about the minimum). Because some of the fibers in cellulose
> are very fine, it fills some of the holes in the walls. When you do a
> blower door test to measure the air leakage in a building before and
> after retrofitting walls with cellulose you will see a measurable
> reduction in air leakage (even at lower densities). If you blow in
> fiberglass you will not see a difference. So how do you install dense
> pack cellulose? you use a bigger hole, 2 to 2-1/2", one per stud bay,
> you insert a 1 or 1-1/4" interior diameter stiff vinyl hose up the wall
> (drilling from the bottom seems to be the best method) and fill the wall
> removing the tube slowly to prevent clogging the hose.The equipment you
> get from Home Depot, or Lowes, or a rental yard is typically not
> powerful enough to get this density. I have a 20yr old Force 2 blower (I
> got it free, $5000 new), but I am only able to get up to 3.2 lbs with
> this method (I don't use a vinyl hose yet, might help), it only has one
> blower, a machine with 2 blowers is probably the minimum. Don't assume
> you installer is doing dense pack, I don't know anybody in my area that
> does it other than me.
>
> Cocoon 2 Stabilized Borate Formula for wet spray installs at 2.6
> lbs/cuft, but because of the glues settling is not an issue as far as I
> know. If you add to much water it doesn't fill around obstructions as
> well. I just learned that the glue is either gar gum or wheat, I have
> problems with gluten (contained in most grains) and need to find a
> supplier of borate only, no glue cellulose insulation.
>
> I haven't done any blow in batt (netting) jobs, but I suspect that you
> can't blow it dense pack without blowing out the netting, or interfering
> with Sheetrock unless you strap the walls. An alternative method is to
> hang the rock and dry blow dense pack after, but before finishing taping
> and mudding, if you want to avoid wet spray.
>
> I have herd good things about Johns Manville Spider spray in fiberglass,
> formaldehyde free, although it probable has an acrylic binder.
>
> The problem with batts is they are typically installed poorly. Gaps top
> and or bottom, compressed in width, don't fill the depth of the cavity
> fully, gaps because not cut around electrical wiring, plumbing,
> blocking, kraft faced batts create a gap at the Sheetrock that allows
> convection currents (even if you face staple and don't inset staple so
> the sheetrocker can find the studs).
>
> You will almost always get better quality from a blow job than from
> batts, even if you get some setting on average it might be better than
> the average batt job. The best batt job is still 10% worse than a spray
> blow in job.
>
>
>
> Keith Winston wrote:
>
>   
>> Hi  Jefro,
>>
>> Many, if not most, cellulose suppliers will supply, often for free, a 
>> blower when you buy a lot of cellulose. Beware: the cellulose to fill 
>> your entire 9.25" wall for an entire house will be a LOT of cellulose.
>> You should look to get it delivered. In which case you might have to 
>> rent the blower separately. Which may not be a bad idea, since the 
>> rentals are sometimes better units.
>>
>> Lowes often sell cellulose around here (Home Depot doesn't), and 
>> they'll give you a cheap rattly little blower. BUT: at one of their 
>> stores, they have a trailer they'll rent you for $40/day, with a REAL 
>> blower in it (and enough room for a fair bit of insulation, but still 
>> only 1/10 of your whole house, probably). You have to make sure you can
>>     
>
>   
>> park the trailer close enough that the hoses will reach everywhere you 
>> need to get to. Otherwise, most freebies and rental units are portable,
>>     
>
>   
>> and can be rolled into position (some are heavy, mine is around 200 lbs
>>     
> I think).
>   
>> A medium-sized house might take a 40' trailer of cellulose. Have at 
>> least 2-3 assistants for blowing, it'll go easier. You probably won't 
>> have a recycler (a big vacuum) so someone will be hauling bags of 
>> overblow back out to the truck/blower regularly.
>>
>> Keith
>>
>> Jefro wrote:
>>  
>>
>>     
>>> Does "DIY cellulose" mean renting a blower and installing cellulose 
>>> into cavities on one's own?  I didn't know that was a possibility.
>>>
>>> We are building a home this fall using cellulose inside a 9-inch 
>>> cavity built from a 2x10 plate and a double 2x4 wall.  We have been 
>>> planning to find an installer to use wet-blown cellulose.  I am very 
>>> interested to hear about other options, although I do have concerns
>>>       
> about settling.
>   
>>> Please continue to discuss!
>>>
>>> thanks
>>>
>>>
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>>
>>     
>
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-- 
Keith Winston
Earth Sun Energy Systems
3927 Madison St.
Hyattsville, MD 20781
301-980-6325
keith at earthsunenergy.com
www.EarthSunEnergy.com