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.

Electrical Rough-In

There isn't too much to talk about that is out of the ordinary here.  One thing I found interesting was that the electrician found it easier and faster to drill holes in the studs to route the wiring, as compared to running them within the 3" gap between the outer and inner walls.  Now that I see it in action, I can see how it's faster to pull through a hole, rather than having to hammer in staples to support the wires.  In the end, it's nice that they weren't pounding on the studs that hold up the Light Straw Clay (LSC).

 Typical wiring.  I took LOTS of pictures of everything since about an hour later, it was all disappearing behind the exterior sheathing.

 With a 3 1/4" deep box in a 3 1/2" wall, there was very little LSC behind the boxes that needed to be cleared away to give access for the wires.  Note the data outlet with the blue wire: he had to cut out the entire back of the box since the wire is so fat and can't be folded up inside like romex.  Mental note: stuff a rag in here before blowing in the cellulose or you'll get a spray of insulation inside the house.  (For the record, I DID remember!)

Sorry that the black waterline is catching your attention, but the intention was to show the neat routing where all the cables enter the service panel.  The fussy guy in me appreciates this attention to detail.  Apparently, this makes a good impression on the inspector too.  He spent more time talking about code issues with the electrician than actually looking at his work.  Another easy sign-off!  Love that!!!

Interior Framing

The interior walls are pretty minimal.  

 This shot shows what it was like to work on foam blocks in order to avoid blemishing the adobe floor.

The floor was too soft to screw into, so the bottom plates are not screwed in yet.  As a result, I have diagonal bracing that keep them aligned.  After the top plates were fastened in, the wall were quite secure and those diagonals were removed.

Ready for the rough-ins!  The bathroom is on the left, and the utility closet is on the right.

For some reason, I'm really excited by the attic.  I guess I just gravitate toward quirky, intimate spaces.  (That may explain why I enjoy camping in tents and cruising on small sailboats!)  It was unnaturally gratifying to cut out the hatch to gain access to the attic.

Drying the Adobe Base Layer

Sorry, I know I'm behind, but as the next few posts will show, there has been another deluge of activity at the practice house.  Here are a few photos showing the drying process for the adobe floor:

After four days, the floor had developed some cracks.  Typically that means the mix was too rich in clay, or that there wasn't enough straw in the mix, or both.  I'll have to fine tune the next layer.

After seven days, a few grains of wheat had spouted, like in the Light Straw Clay walls.  (This was the only cluster of sprouts--there were probably only 20-30 total, with most being a single blade.)

 On day nine, I filled the cracks.  For the larger cracks in the photo, I used a mix of clay and sand in the same 1:2 ratio as the floor and brushed this dry material into the crack.  Using the spray bottle, I wet out the dry mix and used a magnesium float to work the material around to blend the filler in with the two sides of the crack.  The floor was way to soft to walk on, so I was kneeling on 2" thick foam blocks. Note that the clay had been run through a window screen to make sure it was very fine and would enter the crack.  I'm not sure why this photo doesn't reflect the brown color of the adobe, so don't dwell on that.

This shows the floor after smoothing out all the cracks.  Small cracks that couldn't be filled with the dry mix were simply smoothed out with the magnesium trowel after a light spray from the water spray bottle.

After two weeks, the cracks have opened up again, although not as wide as the first time.  This shows the floor as repaired the second time.  I've also just finished the interior wall framing, walking on 2" foam boards the whole time.

While I have no photos, the floor has subsequently endured many trades-people.  After roughly a month of drying, it's now dry enough to walk on gingerly but is still easy to scratch/dent with fingernail or if you drop something onto it.  I didn't think it was fair to ask the contractors to be that careful, so I laid out plywood boards for them to walk on.  They were cool about it, and while the floor's surface is now somewhat haggard looking, it's still in fine shape for what comes next.  Basically, all I need is a reasonably level surface to which I can attach the hydronic heating tubes.  It doesn't need to be pretty at this point.

The Adobe Floor is complete!

Wow, it was a hot week to be lugging around heavy stuff, but the adobe floor is in, leveled, and drying!  A rough calculation shows that I moved around 8,800 pounds of materials, with a little help!  Actually, we moved it twice: once to add the clay, sand, water and straw to the mortar mixer, and a second time to wheel barrow the completed batches into place.  Enjoy the photos:

The first day's progress: four batches.  What's that in the lower right of the adobe?

Cat Prints!  The curious neighborhood feline that likes to visit my barn evidently wanted to see how solid the new adobe material was.  Answer--not very!  Come back in a couple weeks and  it will feel like concrete.

Day two was slow because of all the plumbing penetrations

Moving along on day three, also showing a few tools of the trade.

On day four, a Wednesday, there is hope that I'll finish on Friday and be able to enjoy my Saturday.

And on day five, it's looking like I'll finish easily  tomorrow.

And the payoff... Finished!

It even looks like the photos in the books!

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....