In the previous post, we added the first layer of dirt over the home. In this next step, we add the “umbrella” layer to keep the first layer of dirt dry and warm. The umbrella is made of layers of rigid insulation and billboard vinyls and topped with a pond liner and carpet. Of course, I’ll try to give you some details into the practical construction of this umbrella, but first, the timelapse video.
The Video
Not so easy
When I read John Hait’s book oh PAHS (Passive Anual Heat Storage) he talks about coming up with the umbrella idea because it made it easier to cover the dome in insulation. So I guess I thought it would be the easy part and didn’t really put as much pre-thought into the install as I have for other aspects of this home. However, I was very wrong. It was not easy and don’t let the video make you think it was.
The first challenge was getting the pieces to stay where you put them. This was hard enough on the flat spots and only got more and more challenging for the steeper slopes. I tried a number of things like using wood stakes (I used my table saw to cut a 2×4 into wood weges that were 1/4 inch thick and 6 inches long and pushed them into the sheet to give it traction). The stakes helped with the first layer, but I couldn’t use them on the second. Tape helped a little, but was often foiled by the tiniest amount of sand or moisture. I even tried sliding the insulation between layers of vinyl, but that was difficult to do precisely.
The second challenge was getting the shapes all cut just right. It was enough of a hassle to cut away for the skylights, etc. But dealing with trying to fit rigid rectangles to the compound curvature of a hillside as the sand shifted under your feet was incredibly frustrating.
Then we added the billboard vinyls, which wasn’t too bad. Gluing them with the HH-66 was also pretty straightforward. But once the vinyls were on, the insulation became more difficult to manage. If the underlying layer shifted, it was very difficult to get back exactly how you wanted it (butt jointed with no gaps). It also became much much harder to add the next layer of insulation. Even walking on it was difficult in the steep areas and we kept sliding off. Normally, I would have considered the slide as fun, but it wasted time and messed up the insulation again.
Getting the giant heavy pond liner up there (hardly shown in the video) was also a challenge and dragging it messed up the underlying vinyls and insulation. Pretty stressful actually.
Then the carpet layer helped… It was pretty good in terms of ease of install and its weight actually locked in the underlying layers pretty well while also making it easier to walk around. Most of it was in pretty decent shape and some of it was even brand new (trimming from an install?), but some of it was gross. I recall one had fingernails and other nastiness on it as if it had been stripped from a repossessed home where the evicted tenants were not big on cleaning (I assume people that disgusting were evicted ;).
Regrets
In the end, I had a few regrets.
Primarily, I wished I had put a bit more insulation right up against the vertical sides of the building. It would have been easy to add it there and I wouldn’t have had to worry so much about it after the dirt was added and those steep sections were just so much harder to insulate.
I also wished I had dumpster dived for a couple more carpet loads. It was clear to us that carpet prevented erosion. We only had erosion in the spots that had no carpet. You could see that the erosion stopped in nice square shapes along the edges of the carpet layers. We ended up coming back and adding carpet to those spots, but it was much more work later then it would have been before adding the final dirt.
I am not yet sure if I will regret not putting more insulation. As I said, it is about running out of time and money. Did I insulate enough? Was it thick enough? Did it go out wide enough? Even John Hait says he didn’t think he went wide enough. I think I am OK there, but wonder if I will regret not spending a bit more on insulation at this stage.
Silt Fence
The silt fence was a county requirement with a fine of several thousand dollars if it wasn’t installed after excavation. The regulations include that it should be installed correctly, which requires a trench first so the bottom of the fence can be buried to actually catch any silt that runs off the site. To do this, there is really nothing better than a little tractor with a plow. I highly recommend it to save hours of annoying digging.
One other pro-tip is to screw a piece of scrap wood as a furring strip to the stapled side of each post. Those staples don’t last long and it is much easier to add a strip of wood now that will hold the fabric in place permanently. Or maybe you prefer to go back and fix the fence every few weeks.
Gallery
A gallery of pics… A bit light for this section because no one was feeling like taking pics and it was also difficult to get any good angles on the umbrella anyway.
John chilling for a moment during the hard afternoon.
Sherri on the steepest and trickiest part of the slope.
The little plow from the tractor did a great job forming the trench for the silt fence. Thanks again to the Roe Brothers for loaning it to me.
David was a trooper helping me out that day.
Dumpster diving is fun 😉
Sherri Holding on tight to my belt as I leaned over to put in the screws on the underside of the ledge. It wasn’t something I asked for, but I appreciated the caring 😉
We put lath over the insulation so that a final layer of concrete (stucco) would stick to it.
Building up the layers on the little edge walls.
Sherri glued most of the joints.
We glued the vinyls together with HH-66 vinyl cement. It basically melts them together with a chemical bond.
Follow the instructions and the glued joint is stronger than the rest of the vinyl.
Doing some final gluing with the HH-66
Michael posing for the camera. In the back ground you can see the sand bags we used as weights. Also, the skylight curb got an extra layer to shed water, but its not shown in the video. You will see it in the videos for the final dirt layer.
When you buy a pond liner, they give you a big square. If your pond is round, you cut off the corners. The Roe Brothers (the excavator crew) had kept some pond liner corners from previous jobs they had done and gave some to me. None were large enough to completely cover the roof, but they certainly helped as a bonus layer. The pond liners were definitely more slippery than the vinyls were though.
Keep in mind that the dormers stick out from the actual building underneath, so this is probably covered well enough…
This shot gives you an idea of why it is called an umbrella…
We also built this wall to keep the next layer of dirt off the windows. I think I’ll make that the next video.
David helping me place that last load of carpet.
David messing around for the camera. He lives too close to Detroit.
In order to bury the office apse at the front of our earth sheltered home, I needed to build a retaining wall with a window in it. For this corner of the build, I decided to use CMU’s, Concrete Masonry Units, AKA concrete blocks. We also had to insulate the apse structure.
I may come back and add some detail here. For now, I’ll just post the video and gallery of pics to tell the story.
The Video
The Gallery
Here are some pics to help tell the story.
Sherri getting a selfie
Sherri and I decided to roughly imitate the “American Gothic” paining.
Sherri and I decided to roughly imitate the “American Gothic” paining.
Couldn’t hold the straight face
And back to work…
Camera caught a block drop in mid air and I thought it looked worth keeping.
Michael’s turn to get a selfie
We put 4 inches of XPS between the apse and the retaining wall. This first 4 feet were easy because of the simple curvature.
My mother faithfully working on the insulation dome.
Here Michael is cranking away on the dome. You know this process is decent when an 11 year old kid can crank it out.
Posing with my subway vinyl. In theory, you are only supposed to use these with the image downward, but I couldn’t resist.
We glued the vinyls together with HH-66 vinyl cement. It basically melts them together with a chemical bond.
Perspective…
Here you can see that the insulation layer completely separates the inner and outer walls. The rebar and lath were covered in concrete, ferro-cement style.
It was getting dark by the time I got that concrete up on the eyebrow.
The insulation mosaic was rough looking, but functional.
Go pro caught this fun one as I drove by… I guess I was looking at the camera to avoid driving over the tripod.
While prepping the tower and mezzanine, we also worked on the bedroom eyebrows. It was just too big for one video. More on what “bedroom eyebrows” are after the video.
The Video
Bedroom Eyebrows
Bedroom eyebrows are not some sort of double entendre that only earth sheltered home builders get after a long hard day. They are simply the structures we used to keep dirt off the windows while still having a hilly appearance. You see them in Peter Vetsch earth shelters all the time. However, I suspect (from construction photos) that Peter’s eyebrows are big heat radiators that drastically reduce the thermal efficiency of his buildings. I wanted to avoid that problem, so I needed mine to be thermally isolated from the actual home.
I did this by separating the shotcrete into two phases. After completing the bedroom shotcrete and waterproofing it, I added a saddle of 4 inch thick XPS Foamular 250… This is the kind that can handle 25 psi of pressure and is intended for burial. Above the XPS, I build another rebar framework and put shotcrete over that. Or at least, that is what I wanted to do.
In more practical terms, I used tapcon screws to mount treaded wood 2x4s directly to the bedroom shotcrete. Then I drilled holes in the 2x4s to hold the rebar framework… So there is a little edge all the way around where I sacrificed long-term insulation for a more buildable structure. I have since considered other ways I could have done this and may do it differently if I ever had to do it again, but I don’t think the performance will be too bad. Certainly still better than a more traditional house.
The Gallery
I am tired of typing, you may be tired of reading, so let’s just skip to the gallery.
Various stages of progress
Bedroom south eyebrow rebar
John helping with the rebar above the hall roof
Sherri and I often have end of the day discussions that get caught on timelapse
David was almost 13 and going thru a bit of a goofy phase
Another goofy David Pic
Even Sherri decided to get in on the goofy poses. Maybe it was the heat?
Hunter leaving me an Easter Egg to find. This is the appropriate punishment.
Not to be outdone, Michael also made a number of goofy pics
Michael again
Sherri and David posing for the time lapse cam. They like to leave these little Easter eggs in there for me to find.
Lots of turtles around
Office Apse viewed from the roof of the garage. This big area was going to get a bit water tank, but I ended up deciding it wasn’t worth the money.
Kids playing on the office apse jungle gym
After putting the french drain for the office apse, this time before the shotcrete so we wouldn’t have to deal with any mess
Kids playing on the office apse jungle gym
The eyebrow for the master bedroom apse was the most elaborate