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.
While we were waiting for the shotcrete crew, we continued on some side jobs. One of which was insulating the skylight curbs and protecting them with stucco. Detail on our mix recipe, etc. later, but first, the video.
The Video
The Mix
Here, we used the scratch stucco recipe of
5 buckets (25 gallons) of sand
94 lbs (1 bag) of portland cement
17 lbs (1/3rd bag) of hydrated lime
We mixed this all dry and then used buckets of the mix, mixed with water (about 20 cups) using a drill mixer. After applying the stucco (it naturally forms a layer about 3/8ths of an inch thick), we used a “scratch” tool to give it texture so the second layer would grip it well. Then we left it for a few weeks to cure and watered it often to increase the strength during the cure period.
The recipe for the brown coat was very similar, except with 10% more sand and lime to weaken it a little bit. You want the brown coat weaker so that if it tries to shrink as it cures, it will crack instead of cracking the scratch coat off the wall.
Before applying the brown coat, it is a good idea to wet down the wall. Otherwise the moisture from the fresh stucco is sucked into the scratch coat and it is difficult to work with.
After applying the brown coat, we continued to water it for another couple weeks, again to improve the cure and the strength.
Improved mix
As I mention in the video, along with our improving stucco skills, we also experimented with the mix and found that adding a quart of thinset after mixing in the water really improved the workability of the stucco. It also improved the stickiness (important for ceilings) and gave it some waterproof characteristics also.
The Gallery
Again, sometimes the easiest way to tell a story is as captions on pictures.
The skylight concrete would have leaked a lot of heat. So we needed to wrap them in insulation. But first we needed some wood to screw the insulation too… Necessity is the mother of invention.
This side of the skylight needed more insulation because it included some vertical ducts. I decided I would need to extend the electrical box a little. This was not enough.
In one of the first attempts, it became clear that the electrical would be too recessed.
So, I ended up using a bunch of outdoor box extenders… If it looks stupid, but it works, its not stupid?
Another view of my stacked electrical.
The outlet after we got the stucco around it
Eventually, we covered the wood tops of these with copper…
When you are burying a house, one of the tricky bits is to keep the dirt from spilling where you don’t want it… Like into the doorways. I have a number of retaining walls planned for this build, and, just to keep things interesting, I have designed each one a different way. This section is about the “Heavy Stone” wall by the back door/patio. More details below, but first… the Video
The Video
Cost
I had assumed that those concrete blocks were the cheap way to build a retaining wall and the fancy quarried sandstone was the expensive way. Of course, I probably still would have used some real stone… However, when I looked into it, At least for the cost of the stone, the real stone was cheaper. Of course, that doesn’t factor in things like the cost of the mortar, which was about 5$ per level on my wall, so still not too bad. The real cost of building a wall like this is time… Those precast concrete block walls probably wouldn’t have taken me nearly so much time, but no regrets on choosing to do this one the hard way.
Engineering
Retaining walls often fail. Keys to keeping this one from going down included…
Wide heavy stones (heavy stone is actually what they called this size at the quarry) that are substantial and want to stay where you put them.
Leaning the wall back against the earth load. Before the earth can tip your wall over, it would first need to straighten it out. Gravity helps you keep things as they are.
Curving the wall against the earth makes it a lot harder for the earth to tip it over, just as it is harder for a mug to tip over than for a domino. Making the wall concave helps even further because the loads against it are in compression, something that the stone handles with ease.
Behind the wall, I had plenty of drainage. Drain gravel, landscaping fabric and HDPE corrugated/perforated drain tube were working to make sure that water pressure never gets a chance to build up behind the wall.
Layers of carpet were also used in the dirt behind the wall. This “geo-textile” idea is used by highway engineers to keep dirt from shifting under ramps. I would have liked to have used more layers, but some is better than none.
I watched lots of videos online about how to build a retaining wall that lasts. I recommend anyone who is planning to build there own do the same, and don’t be tempted to take shortcuts.
The Gallery
Here is a gallery of pics with detailed captions.
Here is the delivery. I paid 80$ per pallet, plus something (like 120$?) for the truck to deliver all the pallets.
Here are some more standard concrete retaining wall blocks. If you check the top right, you can see how many linear ft you get per block and calculate how many square ft of wall you would get per dollar. When I compared this with the cost of my quarried sand stone, my sand stone was about half the price.
Before I could bury the garage, I needed a retaining wall, but before the retaining wall, I needed some stucco over these fox blocks… This is just the scratch coat.
Partway thru the stucco job, I checked to see if the camera was still on. This is apparently how I look after a couple hours of night stucco work. (after finishing my regular work day and driving out to the site).
To get a gentle curve, I put down a 20ft long piece of 1/2 inch PVC going thru the marks I had made earlier. Then I put down mortar and started laying blocks.
After a few rows, the wall was already looking interesting and I was already learning.
After the wall was a few blocks high, I back filled for drainage. I also covered this all in landscapers fabric to keep the sand out. Actually, I came back later and filled the whole area with drain gravel, it is easy to use too much when you have a skid steer bucket and order by the dump truck.
After dark it starts to get harder to find the right stones. This evening I probably only got 3 layers in.
The 3rd evening, I got another 3 layers in before it was too dark to find rocks…
The rocks were all aligned against the front of the wall, but the back looked considerably messier. To sort that out, I used my mortar sprayer to shoot mortar over the back of the wall and fill all those cracks. I did it at several stages, this was the first. No pics of the actual shooting because I was busy at the time.
More progress… By this point, I had most of the basics down and things were moving along nicely.
Another pic…
Once the wall reached a certain height, I put these “benches” up against it. We had first made these for the ICF blocks.
Sometimes the kids seek out the camera to get a self pic or just wave at me.
Kids love climbing on walls. However, it can be a problem if the mortar isn’t set yet. This day it was before we started on the wall though.
You can see we have extended the platform. I also added wooden blocks to make it easier to scramble up, but I usually used the ladder.
Random pic
We named our dog Sandy to fit in to the site better. She loves getting up high and looking around.
Sandy chilling on the wall while I worked…
This is how it looks from the ground. I plan to add moss, creepers, etc.
