Blowing in the Cellulose

As I mentioned in the previous post, I have no photos of me and a helper blowing in the cellulose.  It's no big loss, since the process was not terribly exciting from a visual standpoint.  My helper stood by the machine, cutting apart the bales and roughly breaking up the compressed material as it went into the blower's hopper.  Occasionally, theses chunks would create an archway over the paddles that feed the blower, and he had a stick at the ready so he could stir the cellulose and break up the arch and let the chucks fall down.  At the advice of the store employees, we kept the blower door 1/2 open, which controlled how much cellulose traveled through the hose (the airflow is not adjustable).

We did experiment opening the door further to speed things up, and the hose promptly clogged.  Lesson learned--it is a major hassle to unclog the hose!  In our case, the hose had been cut and patched in two locations, which created pinch points to initiate the clog.  We untaped the sections, beat the hose repeatedly, and raised it up to shake out the loosened material inch by inch.  All told, we probably spent an hour unclogging the hose and repairing it.  Two person-hours wasted!

I manned the nozzle, and it was probably even less exciting to watch.  I pretty much stood there and slowly twisted the nozzle while pointing it down into the cavity in an attempt to distribute the cellulose evenly and avoid having it hang up on the Light Straw Clay (LSC).  It's easy to tell when the cavity is filled up to the nozzle since the sound of the machine would raise in pitch.  It's very similar to the sound change when the hose on your vacuum clogs.

Since the stud cavities are interconnected via the thermal break between the inner and outer walls, there was a fair amount of material that would blow into adjacent cavities.  Sometimes, dust even blew out the adjacent fill hole.  For this reason, I would fill all the lower holes in a section of wall before moving to the upper holes.  In the upper holes, I'd start by pointing the nozzle down, and at the first sign that the level of cellulose had risen up to the nozzle, I'd rotate the nozzle up into the the cavity above the top plate (see photos in the previous post).  Once that area was filled, I'd slowly back out the nozzle and sweep it around to make sure there were no remaining voids.  As the nozzle was just about to emerge from the hole I'd signal my helper to turn off the blower.

It ended up taking about 7 hours to blow in 35 bags.  I was left with a bunch of 2-inch holes that were plugged with cutouts made with a 2 1/8" hole saw.

 The plugs were held in with temporary duct tape so the building inspector could see inside if he wanted to.

 After he signed off, I used construction adhesive to glue in the plugs to make them water tight and airtight.  The adhesive has been strong enough to withstand stapling on the tar paper and nailing in the shingles, with only one that came unglued.

Oh yeah, and on the same day we did this, the spray foam people installed the closed cell foam in the attic.  I have mixed feelings about the spray foam.  Its certainly not a natural building material, and it's expensive.  But it is an ideal insulator in so many ways: something around R-6.5 per inch, it seals out all air infiltration, moisture cannot condense in the insulation so it won't mold, and there is never any settling or other potential installation defects that significantly reduce the effectiveness of batts.  In this house, where I expect to be up in the the attic regularly, I thought it was the best option.  If I had an attic that was not going to be lived in or used often, I would blow in cellulose on the attic floor and just live with the 12-15 inches of depth that is required to comply with the IBC insulation requirements.