Adobe Floor - Top Layer

OK, I've done as much work as I can do before installing the kitchen cabinets, so it's time to lay in the finished layer of adobe floor.

First, one final effort to stabilize the cracks.  I filled the few remaining
void areas with dry sand/clay powder and wet out the entire crack.  Then I  traced
the cracks with a fat popsicle stick, pressing down as hard as my fingers
would allow.  Last, I pounded the crack with a short stick to densify the material as
much as possible.

The pour progressing nicely.  Note the plastic on the walls to protect
against splatters.

Friends had helped me pre-mix 4 batches in the mortar mixer the day before.
(The recipe was 1 bucket clay, 2 3/4 bucket masonry sand, 1/3 bucket chopped straw.)
The goal was to install the entire top layer in one day to avoid having joints show
in areas poured on different days. I ended up needing a total of 8 mixes, but because
this was Monday, I had no help available to parallel process mixing and troweling.

It ended up being a 14-hour day, but I got it done!  Here, is the floor a week later
after drying out.  Unfortunately, it dried out too much.  It was still a little too wet to burnish
on Friday; I was away for the weekend; and this was how it looked on Monday before I did
the burnishing.  I had to use the paint sprayer to re-wet the surface, but it was still
not as good a job as if I'd been able to do it a couple days earlier.

Still a little wet after burnishing, so I walked on the foam boards
to avoid denting or scuffing the surface.  Luckily, there were no
issues with the painters tape damaging the clay wall plaster, so the
plastic came down without drama.

My Cinderella moment: if your hand fits the print in the floor, you own the house!

Change of Season

Saturday was one of those gorgeous late November days you dream of having on a weekend: sunny, upper 60's and light wind.  Friends and I spent the bulk of the day happily tackling several tasks on our sailboat.  Until precisely 4:23, when the weather signaled that it was time to quit for the day.  We could hear the wind coming with the cloud bank, and practically instantaneously, the wind increased from a near calm to 30 mph gusts that whipped debris into our fresh paint (damn!).  The temperature dropped 10-15 degrees over the next 30 minutes.

So how is this relevant to the house?  Earlier that day, the interior temp was in the mid 60's.  Sunday, was a brutally windy day (gusts to 40 mph), with a high temp in the mid 40's with mostly cloudy skies.  The house sat un-visited with the windows closed and the heat off.  Monday morning, with the wind still gusting to 30 mph and overnight lows around freezing, I came in around 7:30 to find the interior temperature at 57 degrees.  But at least the sun was out!  By 11:00, the passive solar brought the temp up to more respectable:

I guess the framers were right when they said I'd be able to heat the place with a candle!  Perhaps the more noticeable experience is stepping inside and hearing the noise of the roaring wind diminish to virtually nothing!  The house has no creaks or other indication of the nasty weather outside.  And all thanks to simple stuff like sand, straw, wood, clay and paper!

Adobe Layer 2

After dealing with cracking in the first layer of the floor, I wanted to refine my sand/clay ratio, so I tried three more samples at 0.83:1, 1:1, and 1.25:1 rations.  Here are the results after 17 days of drying:

Sample 1

 #1 Obvious failure: too much clay caused it to shrink and crack.

Sample 2

#2 Not too bad, but still a few cracks.

Sample 3

#3 Almost no cracks. Is this the one? I thought I'd try a fourth mix with still more sand to see.

Sample 4

#4 Formed one week after sample three, this one had cracked pretty significantly after only 10 days. So the winning recipe is 1.25 parts sand to part clay.

Most of the first day was spend in the bathroom, sloping the floor to drain to the shower drain and getting a level surface near the toilet. There is still a 1/2” layer of lime plaster to go on top, but I wanted to be relatively precise so that layer can be relatively uniform in thickness. I also wanted to practice creating an attractive, sloped surface.

Here is the main room after day two. Things are moving along much faster with the 1 1/2” layer as compared to the 4” layer! Hopefully the dry-time will be less. Even though the house is closed up, my desiccant dehumidifier appears to be doing a great job of sucking out moisture and warming the room.

Radiant Tubing

I am SO looking forward to experiencing radiant heat!  Think about it: warm feet, nearly constant temperatures with low energy input, no filters to change, no noisy and uncomfortable air blowing out of ducts, no worry about whether there is mold growing in your ducts: the advantages are many.  And in a house this size, it is so simple: There is only one run of 250 feet of pipe, so no manifold and network of thermostats.

The  1/2" diameter PEX tubing was pretty easy to install, even though my friend and I were near the bottom of the learning curve.  (This would be a tough task to accomplish solo.) We spent a couple hours learning that the 1 1/2" tapcon screws were having trouble holding in the adobe base layer, which is noticeably softer than concrete.  Solution: 3" course-thread deck screws driven straight down with no pilot hole.  Not one of those has pulled out.  True, we didn't pull the tubing into quite as small a radius as we might have otherwise, but I don't think there will be any downside.

The only place were we doubled on clips up was where the tubes transition from the floor up the wall to the heater/pump assembly.  You can see the blemish in the adobe where one of the tapcons pulled out.

So next step is to bury the tubes in a 1 1/2" layer of adobe.  That thickness makes it easy to use 2x3s laid flat as screed boards.  The entire adobe assembly consists of the base 4" layer, the next layer at 1 1/2", and the 1/2" finish layer for a total of 6".  That's a lot of thermal mass!  So I'll basically set the thermostat once in the fall and leave it untouched until the end of spring at the end of heating season.

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....