Earth sheltered homes normally get very scaled down heating systems (some even skip them entirely). Where I live, a heating system is required for occupancy, so rather than get an expensive furnace that I would hardly use, I decided to go with an inexpensive “on demand mini boiler” hot water radiant system. I got quotes for install that were as high as $60,000, but figured I could do it for a small fraction of that, so I decided to pull my own mechanical permit and do this myself. I read a couple books and planned it out. Then I bought the manifolds and supplies from PexUniverse.com (less than 400$ for the basement).
We got it all installed and inspected (our first mechanical inspection) and then had Dysert Concrete handle the actual pour of the floor.
Installing the radiant floor was easy, but some of the recordings didn’t work out, so the final video is shorter than usual. You can read the story below for the details that wouldn’t fit in the narration.
The Video:
The Story:
I started with working out the layout on the computer. Building code requires that no circuit be longer than 300 ft, and most experts recommend that you balance the lengths of the radiant tubes, so you definitely want to plan it out ahead of time.
I tried a number of different plans that ran the tubes thru the hall to the various rooms, but it was just too inefficient and cumbersome to get things “zoned” well that way. In the end, I decided to drill some 5/8ths inch holes thru the base of the mechanical room wall to simplify the layout. With the right tools (DeWalt hammer drill and a long 5/8ths inch bit), that was pretty easy.
We had leveled out the pea stone after the “underground inspection”, but David helped me do some final leveling of the peastone and then Zack helped get the 6 mil plastic down. This plastic is important for keeping water vapor from the ground out of your concrete floor and is required by building code. It also helps keep the radon out, etc.
Six MIL?
A mil is not a millimeter. Six MIL is six thousands of an inch or roughly 0.152mm. Before most English speaking countries switched from the imperial measurement system to metric, they would have called it a “thou”, based on the Germanic route word for “thousandth”, but for some reason, America decided to go “romantic” language based with this one and called it a “MIL” instead (based on the word for “thousandth” in languages like French or Italian). This is a similar etymology to how the rest of the world got the word “milli” for the Metric system, hence the similarity.
We don’t use “MIL” much in the USA, except for quantifying thin film thickness.
Since it is difficult to imagine things in thousands of an inch;
1 MIL = grocery store bag
2 MILS = Garbage Bag
3 MILS = Husky Contractor Bag
17 MILS = Pond Liner
35 MILS = Credit Card
JigSaw Puzzle
David tossed us some sheets of insulation and we got started on the jigsaw puzzle. My rooms are unusually shaped and since they didn’t actually stock those shapes at Home Depot, we cheated by cutting pieces. We started with measuring, but usually ended up trimming each piece iteratively until it fit. We taped all the pieces together and shoved trimmings into any gaps along the wall. Not too hard, but certainly more time consuming than a square room might have been. This probably wasted about 15$ worth of insulation, so not too bad.
Radiant tube
I marked the radiant tube layout directly o n the insulation based on that balanced plan I had carefully worked out on my computer. I used piece of scrap wood marked with the right size increments and a can of upside down surveyors paint. In addition to basic tic marks to follow, I also painted in the end loops so the whole plan would be pretty easy to follow.
Stapling the Pex tubes down was easy and fun, Sherri and I took care of most of it, but the boys were very eager to try it themselves. I imagine it would have been quite a lot more difficult (and much less fun) without that commercial grade tool we used. The tool cost quite a bit (~200$) but is very well built and I will use it a lot… I also plan to sell it and recoup most of the money at the end of the project anyway.
Connecting the pex to the manifold was straightforward and easy. There are some simple little brass connector bits and you just tighten a nut to hold it all together.
I got the Manifold, Pex pipe, the Pex stapler, staples and the pressure tester from “PexUniverse.com”. I had looked at lots of other sites (including sites that put it all together for you, such as Radiantcompany.com), but this one had the best prices and the best hardware. There are also easy to find “coupon codes”.
John (my brother-in-law) and Zack helped me finish off the third loop.
My sister Bonnie was in town and mostly helped me with the ICFs (another post/video), but she made it into this video by helping me to fill the tubes with water so they wouldn’t float in the concrete. I had been trying to pour it from the bucket into the funnel, but she had the idea to siphon it from the bucket, which was much easier and didn’t get us as wet.
Then we pressurized the system (according to building code) so we would know if anyone punctured the pipe before the concrete set.
Concrete
Concrete day arrived and the guys started with putting down some six by six wire reinforcement. This was left over from the garage floor and will help prevent cracks from growing. It also helps protect the pipe and keep it all down under the concrete.
The concrete was pumped in from overhead (renting the pump truck cost ¼ of the job, but was well worth it in terms of making things go easier), and spread level. They came back an hour later and hand troweled it smooth.
Costs
In all, I paid less than 1$/sft for the insulation, radiant tube, manifold and supplies, then 3$ for the concrete work plus an extra ~500$ for the pump truck and ~1100$ worth of concrete… So, not bad.
I hope to get the “quad deck” in soon so we can put another concrete floor over this basement.
This video could have been about a lot of things… It could be about appropriate ways to get you kids involved in construction… Or about how I tried to hire for this basic task so I could focus on the trickier parts of constructing my earth sheltered home…
But in the end, the worked needed to get done, so I got my 10 year old to start on it one afternoon after work/school. David is a pretty good worker, but I didn’t mind him taking breaks (lots of breaks) with the bee bee gun. On another cool spring day, I went out there with my younger son. Generally speaking, they are very different personalities (Michael is also younger and therefore less suited to digging or working independently), but I was still pretty proud of how well Michael worked. He also enjoys the bb gun, but he actually spent most of the evening with me working on the rib forms (a separate video). On each of these evenings, we took a break to go walking (and shooting) in the woods.
That Saturday, the whole family came out. While I was working on welding steel arches (another video entirely), the rest of them got to digging. My wife, Sherri, did the majority of the excavation until the bedroom footings were completely uncovered.
I took the following Monday afternoon off work and came back out. This time, I managed to hire some students to excavate while a friend helped me with welding. These two teens were scratching their heads as they uncovered my footings like archaeologists with no idea of what layout to expect.
Side note here… I had some trouble with my generator (mentioned in another video) we ended up taking the carburetor apart, etc. It turned out the carb was fine. The oil level was just a tiny bit low and the “low oil” sensor was “almost” shutting things down as the oil was drawn up into the engine.
It took the teens several hours to clear the footings. My wife thought that was money well spent. Next I had them switch to clearing all the bracing wood out of the basement. We ended up moving it away with the skid steer. I offered them a 3rd job, but they were pooped and decided to go home instead.
Now that the wood is out of the basement, we can try to get these teens back to help clear the concrete slag out of there.
At the moment, the construction schedule has 3 main paths.
1) On the east side, we are getting the steel arches rolled. We can start to erect those after the excavator comes in and sorts out the grading issue, but they are waiting on the frost laws to allow them to carry their heavy equipment on the roads.
2) On the west side, I am getting the Quonset hut ready as a work shop to build the wooden forms for the precast concrete ribs.
I probably have a months worth of work on each of these sides before the paths converge on the middle.
3) In the middle of the house, I need to get in these steel posts that will support the ring beam that will eventually support the precast concrete ribs that will eventually hold up the steel arches and shotcrete that will form the radial vaults.
This weeks video is about setting up the posts for the center section.
The Video
The Story
I’ll put the story in here to provide a little more detail and to make it text searchable for Google ;^).
Working backwards:
In this region of the earth sheltered house, the load from earth above (not shown) is directed, by the radial vaults (made of heavy shotcrete over steel arches), down onto the precast concrete ribs.
On the outside edge of the house, these radiating concrete ribs (which weigh almost 5000 lbs each) are sitting right on 4’x4′ concrete pads made of strong reinforced concrete 1 ft thick. However, at the middle of the house, the high end of these ribs are set into a central tower made of shotcrete (which will carry most of the final loads) over a steel skeleton (which will carry all the loads during construction before the shotcrete is in place). This image also shows the QuadDeck ICF floor forms. When concrete is poured over these, it will help lock the steel posts into position.
The load of those 10 heavy ribs runs thru the ring beam and down the structural steel columns into the shotcrete basement wall below.
The 3D CAD model shows a nice flat surface where these pipes attach to the top of the basement wall.
The reality is that the shotcrete guys did not do a great job of squaring off the edge of this wall, probably because it was 9 ft tall and hard to reach. I needed to fix that. I setup some cardboard forms to the level the wall should be at and backfilled with hydrolic mortar. It was thin enough that it was pretty much self leveling.
The next step was to prepare the steel bases. I bought a box of scaffold bases for $4 each, but the (nail) holes were too small to fit the anchors thru. I drilled them out using the lowest setting on my drill press and some lubrication.
Drilling steel requires low speed and lubrication. I lubricated with thread cutting oil. The smallest container I could find was much more than I would need and only cost ~4$, the drill bit was 7$, so I used the lubricant generously in order to preserve the life of the bit. I found applying it directly to the bit was the best way. If the bit started to smoke, I would stop the drill and add more oil. If the speed/pressure and lubrication are correct, long spirals of metal will come off. This indicates that the steel is being cut and not just wearing away the bit.
Then it was time to head back out and mount the bases to the wall. I was using sleeve anchors that require you to drill a hole first, and then drop the anchor in the hole. It is important that the sleeve be completely below the surface. When you tighten the nut, the sleeve is expanded and presses against the sides while the nut pulls what ever you are attaching down toward the sleeve… I was in a rush and didn’t put one of the first anchors in properly. There was probably dust in the hole. But I couldn’t pull it out again either. With the sleeve too high, the nut tightened against it before pressing the metal to the concrete, so it would never be tight. Eventually, it will be under another ft of concrete, so I was not too worried about it, but I put the rest in more carefully.
I was also careful to make sure each scaffold base was level so it would be easier to plumb the columns later.
My steel posts were ready a couple days earlier than promised (a first for me on this build), so I picked them up in my trusty trailer. They weighed about 100 lbs each and put the trailer near its official limit, but it felt like it pulled easily.
The following weekend, my parents visited with my sister.
The mission was to move the steel posts into position on the base plates, hold them steady and level and then tack them into place with my welder. The first one worked pretty well. But the welder jammed on the second one. I couldn’t untangle it, so we had to cut out all that welding wire and re-setup the machine. From then on, I always checked the wire spool every time I moved the welder to make sure that it was not tangled.
This third post was the one on the less stable base, so we added extra bracing to keep it plumb until the concrete is poured around it. We had a lot of experience pluming steel last summer, so everyone knew exactly what to do and it only took a minute or so.
My sister and I both enjoyed the welding, so we took turns welding vs holding… Some times on the same post if it was tricky to access a certain point. The most time consuming part of the process was simply adjusting the scaffolding, etc. so we could reach what ever we needed to reach.
It took us about an hour to get the first 5 posts in, but they were on the side of the circle that was easy to reach. We were expecting the back side, were we had to balance on the wall, to be more difficult, but it was pretty easy too.
After all the posts were in place, I was worried that someone may give these a good push and cause them to shift… Yes, they are welded to steel plates bolted into strong concrete with 3 inch steel anchors, but an 8ft long 100lb lever would probably be able to pry those out.
I wanted to weld the ring beam on right away, but each half was 320 lbs and I couldn’t think of a safe way to get them into position.
So we decided to weld some rebar between the posts as a temporary solution. This was nice and easy and I really liked the look of it, so it will be sad to have to cut most of it off again when we need to put the door bucks in.
I was not sure how far my tank of shielding gas (Ar and CO2 for the MIG welder) would go, so we only did tack welds. That turned out to be a good decision because it ran out just before we were done. Without the gas, the final few welds looked pretty ugly.
After that, we put in some work prepping the shop for building the forms, and I will talk about that another time.
The next step in this center section will be getting in the QuadDeck ICF (insulated concrete form) floor over the basement. I am having a painful time getting that scheduled.
The rest of the steel arches are still being rolled and I will soon start on the forms for the ribs.
We don’t use “MIL” much in the USA, except for quantifying thin film thickness.
Stapling the Pex tubes down was easy and fun, Sherri and I took care of most of it, but the boys were very eager to try it themselves. I imagine it would have been quite a lot more difficult (and much less fun) without that commercial grade tool we used. The tool cost quite a bit (~200$) but is very well built and I will use it a lot… I also plan to sell it and recoup most of the money at the end of the project anyway.
I got the Manifold, Pex pipe, the Pex stapler, staples and the pressure tester from “PexUniverse.com”. I had looked at lots of other sites (including sites that put it all together for you, such as Radiantcompany.com), but this one had the best prices and the best hardware. There are also easy to find “coupon codes”.
