[Greenbuilding] Cellulose settling

Thu Jul 27 11:16:55 CDT 2006

I'm no loose fill expert, but I have read my Heisenberg.
I wonder if the "experiment" might not have inadvertently skewed the
"results" by introducing a factor not found in the standard case: the net.
My guess is that the net would be prone to sagging outward (away from the
cavity) under the conditions/pressures Laren outlined, facilitating movement
or expansion + slumping in a way that drywall would not. This is just my
speculation.

Reuben Deumling

On 7/27/06, John Salmen <terrain at shaw.ca> wrote:
>
> Had a chance to look at an installation done for a homeowner who was in
> the
> building industry (it was done with a net - drywall off) - at 6 months
> there
> was 6-8" settling and the owner topped it off - at 12 months it was down
> 2".
> Original installer did everything to spec. for density of installation. It
> was done this way as the owner wanted to ensure a properly insulated wall
> and didn't trust the material.
>
> A void is inevitable - the material spreads to fill and settles under its
> own weight, it isn't pixy dust.
>
> John
>
> TERRAIN E.D.S.
> 4465 UPHILL RD
> DUNCAN BC
> CAN V9L 6M7
> PH 250-748-7672  FAX 250-748-7612 CELL 250-246-8541
> terrain at shaw.ca
>
> I had three pieces of limestone on my desk, but I was terrified to find
> that
> they required to be dusted daily, when the furniture of my mind was all
> undusted still, and threw them out the window in disgust --Henry David
> Thoreau
>
> -----Original Message-----
> From: greenbuilding-bounces at listserv.repp.org
> [mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of John Straube
> Sent: July 27, 2006 8:07 AM
> To: greenbuilding at listserv.repp.org
> Subject: [Greenbuilding] Cellulose settling
>
> I agree with Loren -- there are no facts to support the contention that a
> DIY dense pack will be a problem.
> It is pretty hard to screw up dense pack cellulose or even damp spray
> relative to other types of insulation. DIY insulation is almost always
> installed better since the installer really cares and spends lots of time.
> Weatherization people from all areas of the country who insulate homes and
> then infra-red camera inspect constantly tell me that cellulose installs
> better than any other practical insulation based on real-life inspections.
> Some fibreglass products are now appearing that are blow-in and spray in
> (eg
> JM Spider)to solve some of the poor quality install issues FG has.
>
> Dr John Straube
> Associate Professor
> Dept of Civil Engineering & School of Architecture
> University of Waterloo
> Waterloo, Ont., Canada
> www.civil.uwaterloo.ca/beg
>
>
> -----Original Message-----
> From: greenbuilding-bounces at listserv.repp.org
> [mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Laren Corie
> Sent: Thursday, July 27, 2006 10:07
> To: greenbuilding at listserv.repp.org
> Subject: Re: [Greenbuilding] was Diminishing returns / obsessingover
> bridging
>
>
> "Lawrence Lile" <LLile at projsolco.com>
>
> > DIY blown-in cellulose, installed between existing studs
> > and not done by a pro will probably settle and have gaps.
> >
> > --Lawrence Lile
>
>     I have seen no factual basis for such a statement.  There have
> definitely been bad blown-in wall installations, by unscrupulous pros who
> have cheated homeowners by using too little material. However, there is
> nothing to suggest that a DIYer would ever short himself, when the only
> way
> to tell that the wall cavity is full is that the blower stops moving
> insulation and the hose buckles.  You simply fill the hole until it won't
> take any more insulation. Cellulose will naturally
> settle to roughly 1-1/2 lbs/cu ft density.     It gets blown into walls
> at between 3.25 and 3.75 lbs/cu ft. So, it is packed in way tighter than
> its
> natural settling density (like a spring, or foam rubber in a cushion).
> Vibration will not cause it to settle. It does the opposite. It will cause
> it to expand into every tiny area. Since there is far more cellulose in
> the
> wall cavity, than its natural settling density, it simply can not slump.
> It
> would be highly unusual for any area of a wall cavity to remain empty when
> that same cavity was filled with insulation.  Locating the holes is not a
> complicated task.  A hole near the top, and another near the bottom, will
> give even enough packing for no slumping to occur in normal height walls.
> Taller walls simply get an additional hole. Since the insulation value of
> cellulose is in the fibers, instead of in the gaps between, there is no
> loss
> of R value by increasing the density over that used for loose fill
> installations. At either its loose fill density, or the 'dense-pack'
> density, the R value is around 3.7-3.8/in.
>
> However, there has been evidence that some foam insulations
> can lose their bond with studs, leaving gaps where air can pass.  This is
> why gaskets are beginning to be used around windows and doors, instead of
> foam fills. This loss of contact should not happen with 'dense-packed'
> cellulose, even in
> narrow spaces, where there might be frame movement.
>
> -Laren Corie-
> Natural Solar Building Design Since 1975
> www.LarenCorie.com
>
> -LittleHouses- http://groups.yahoo.com/group/LittleHouses
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