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.

Insulation Preparation

The exterior walls are 12" thick.  The inner 2x4 studs are filled with Light Straw Clay (LSC), and the remainder of the 12" will be filled with blown-in cellulose insulation.  Lowes makes it easy: buy 20 bales of Green fiber insulation, and you get free use of their blower.  Like most tasks, there is a fair bit of preparation that needed to happen in order to streamline the process.

Most notably, the light straw clay only extends up to the bottom of the I-Joists that form the ceiling, so I needed to add blocking to seal off the cavity at the ends of the beams.

I nailed plywood panels in using wooden cleats, top and bottom.  To avoid having to measure precisely, I just left about 1/8" clearance all around and caulked them tight.  That took care of the north and south walls.

The east and west walls were easier, since I could just nail up luan plywood strips to the studs (that's the reddish strip on the left of the photo).  The 1x2 straps below the luan will support the drop-in ceiling panels, and they do double duty by giving a clean line for the luan to butt up against.  

For the most part, the stud cavities were filled from the outside via holes in the exterior sheathing.  The one exception was that the areas under the windows were more easily accessed from above.  I bought a GreenFiber Nozzle to reduce the 2 1/2" hose that comes with the blower to 1".  They even sell plastic plugs that make it super easy to plug the 1" holes.   Those are the white circles, with the window on the left of the photo and the 2x4 LSC inner wall on the right. 

I supplemented the GreenFiber nozzle nozzle to help me control the direction of the cellulose as it is blown in.  All I did was cut off the last 3" of the nozzle (after filling in under the windows) and duct tape it to a 1 1/4" diameter long-sweep 90 degree electrical conduit elbow.

I had to determine how far below the top plate of the walls to locate my 2" diameter hole so that the nozzle would point up above the Light Straw Clay.  The magic number was 7 inches to the center of the hole. 

This allows me to blow up to fill in the area between the I-joists and behind the blocking I described above. 

 It's also desirable to point down and towards the plywood.  Since the LSC can be rough, I prefer that jet of insulation to hit the smoother plywood since the straw might tend to catch the insulation and leave gaps below.

It was a hectic day when it came time to buy the insulation and haul it along with the blower machine to the house!  For better or worse, I don't have any photos or videos of that process since we were pressed for time.  More on that in the next installment,.

Sheathing and Windows

This day involved the most overt progress since the framing went up back in July!  The sheathing went out without any drama, thanks to pre-planning by the framers to place studs 2' apart.  But first I had a little work to do to fill up some cavities in the studs that were too narrow for me to blow in with cellulose.

It's pretty low-tech: stuff the gap with rigid foam and use spray foam to seal it in place.  Once the foam dries, I sawed of whatever stuck out.

Big excitement when the windows and door arrived!  Note the sheathing in the background, closing in the Light Straw Clay.  (Finally, I won't have to worry any more about a driving rain re-soaking the LSC.)

Here is my idea for a termite shield: I screwed a strip of the trim material below the sheathing.  The TruExterior, manufactured by Boral, is made up of recycled fly-ash and resin, so no insect will want to eat it.  It is dimensionally stable and immune to water damage, so it will do double duty to protect the exposed bottom edge of the plywood.  So the only thing a bug will see from the ground is cedar (which is naturally insect resistant), TruExterior, and concrete.

All the windows are in!  Ready for insulation.

Adobe Floor Preparations

There are several layers that need to be installed before I can start with the adobe:

Four inches of pea gravel.  The discoloration is due to the gravel being slightly damp from the previous day's rain.  Note the hand tamper: that was a lot more work than I'd anticipated.  If the space had been bigger, I probably would have considered renting a gas-powered tamper.

The next layer up is the 6 mil polyethylene vapor barrier.  However, before I installed that, I pre-fit the first layer of foam (1-inch thick) and cut holes for the pipe penetrations.  This photo shows how I used the foam as a template to know where to cut the vapor barrier for the pipes.

With the poly in place and stapled up the wall, I taped the vapor barrier around the pipes using Zip Tape.  I don't have a picture, but the corners are folded like Christmas wrapping but on the inside.  Since the goal is to make the poly as air-tight as possible, it's better to avoid cutting: hence the corner folds.

This shows the second layer of 2" foam in place at the other group of pipes.  At R-5 per inch, this provides a total of R-15 under the radiant slab.

Practically done:  The joints have been taped, and spray foam has been added around the pipe penetrations.  The last thing to do is glue the side foam panels down and tape the side joints.  It was only a matter of a couple hours until the first load of adobe mix was flopped down and leveled.  More on that next....