Saturday, our kids each had soccer games, one after the other. Each of my boys won their games (3 to 2 and 5 to 3). By the time the games were over, it was mid afternoon, we dropped them off with their grandparents and headed out to survey the basement. We were using a builders level that I rented, again. We had to do the job again because all the previous stakes were dug up during the excavation. Well, I should say most were dug up. Sherri had run some extra stakes further out so that we could re-establish the location of the center of the house. The excavators had been careful not to disturb those markers.
When we got there, it was kind of cool to be able to drive up our new driveway… Its the little things ;^)
We started with the long line that Sherri had marked out before the excavation. We tied some masons line between the stakes that she had placed 50ft on either side of the center (the excavation was about 60 ft across). We tied a plumb bob to the mason’s line at the middle point and let it hang into the excavation. The sand was also very soft and rough, so I spent some time flattening the area, especially around the hanging plumb, with my 10” tamper. I then positioned my marked concrete paver (90lbs) centered under the plumb and lined its etched angles up with the mason’s string overhead. Then we setup the builder’s transit over the paver (I finally have that setup process figured out after three rentals). Again, I used the overhead string (and the lines etched on the paver) to orient the transit. It took us about an hour of setup before we placed our first stake, but once we did, the rest went fairly straight forward. Since most of the key points for this design are positioned radially from the center, we just needed the transit for the angles and a measuring tape for the distances. This marked out the centers of the edges, then we offset these stakes by one foot (half the width of the footing) to get the true outer corners. In one corner, we use some Pythagoras (3-4-5 triangle) to square things up. We also put a lot of “extra” stakes in to make the curved shape clearer and topped it off by tying string along the perimeter of the footings. We actually had brought surveyors paint, but it didn’t work well on the sand.
The pit had not been excavated far enough and I had to do some manual digging along the way. The soft sand was easy to dig (I did all the work barefoot and pretended I was at the beach) but as I dug, the sandy wall would cave in and give me more to dig. I couldn’t throw the dirt out of the hole, so I tried tossing it “out of the way”. But I didn’t put it “out of the way enough” and I had to dig some of the same dirt again when I got to the next stake. Sherri thought that was funny. There were a few areas that had so much sand I just gave up and stuck the stakes in about where they would be. We called the excavator to come back and widen the excavation. That was a bit disappointing because it meant we would need to delay the start of the footings. Anyway, we got it all staked out by 9:20 PM (just before it got dark), but it was probably closer to 10:30 PM before we completed the long drive back and picked up our kids (an hour and a half later than planned), so we appreciate that my in-laws were merciful and hope they will still help us out next time ;^).
Hopefully the Excavator will go back and take care of the over-dig without disturbing these stakes or the centerstone marker (paver) too much and we can get to work on the footings. I found out that my footings guy uses a “Total Station” builders transit. It has a computer that does all the trig for you. We will let him stake it out next time. I just need to figure out how to transfer my drawings into the right format.
So, at some point, I decided that I wanted to build myself an earth sheltered home. This is not like saying I would like to build a colonial or a bungalow or something that has some know design DNA, or that uses known systems and processes… This is a wide open endeavor with a wide range of possibilities and even more unknowns. I have always been an Architecture buff, so it would have to be nice looking and functional. The engineer in me wanted to build an “engineered house”, what ever that is… I wanted it to be light, but authentic, and a bunch of other vague ideas that would have left any architect scratching his head. Of course, this wouldn’t just be my vage want list, I had a wife and kids who were also giving vague input. My kids wanted tunnels that connected things impossibly (they were not worried about the engineering or cost). My wife’s wants were harder to nail down, but she knows when she doesn’t want something ;^). But everyone was pretty supportive of the overall idea, so I started trying to add specifics to the vision…
Of course, I started by searching the web for other examples (check out my links page). The range was quite wide, from free-form (curvy) shotcrete vaults without a straight line in sight to more “practical” homes with concrete block walls and simple flat roofs. Some basically just buried Quonset huts (maybe a nice cottage idea some day). I have a big folder full of pictures in my computer. I wish I could share them all here, but getting permissions would be too much pain. Instead, here is a google image search, and here is another. The variety is amazing.
Many of the photos came with detailed blogs about their construction. Many were home builders who kept their budget low and did all the work themselves. I did like that idea, but I am full time employed and too busy to build my own home by hand. I am willing to spend a little more (not mortgage phobic) and wanted something more architecturally interesting. You could also see that many had a lot more money than I did (Bill Gates lives in an earth sheltered home), so I won’t be on that end of the spectrum either. There was also a strong contrast between those that were built without any compromise on the scientific principles (no north windows, brown cement floors, insulating shutters, tromb walls, etc.) and those that were built as art, without any consideration for the scientific principles. I wanted to stay married, plus I am a little artsy myself, so I plan on compromising where I need to. For instance, I plan to have a number of windows on the north side to capture the view even though I know they will leak precious heat. I also plan to have rugs on my floor although they inhibit solar gain into my storage mass…
I shared these ideas and pictures with my wife in an “agile” way, trying to get as much input as possible. For instance, i found it interesting that my wife really liked the concrete block or “ICF” idea because she liked the simplicity of the Lego-like construction method. I also discovered that she thinks about thinks like curtains very early in the design process… ;^) So, we initially co-imagined a rather rectilinear cement home (but with fibonacci proportions) with an undefined roof type (research pending) covered in some unspecified thickness of earth…
We cut these standard room sizes out and arranged them on the dining room table
For the actual layout of the home, I got some plan books and looked at single story homes that were about 2400 square feet. I took the room sizes from those and made a bunch of scale room tiles. Sherri and I printed these out and shuffled them around endlessly as we talked about design concepts.
- How do we divide the public and private areas of the house?
- How do we keep the TV noise out of other areas?
- Where can Simon’s office go? (I work from home 80% of the time)
- Why do people put laundry rooms by the garage instead of next to the bedroom?
- Do we need somewhere for our guests?
- How can we keep it affordable and make it interesting?
Also, we didn’t like the idea of an entry that appeared to be leading to a bunker. We wanted the functional areas of house to be on one floor, but I liked the idea of a “storm room” like a gazebo/conservatory on the roof that would give me 360 degree views. I thought a zero flush urinal in the boys bathroom would be a good idea. I really wanted a courtyard, but that idea morphed into a more practical green house or sunroom.
We some how expected that we would be entering from the North side (the earth bermed side) and wanted to avoid the bunker look, so we came up with the idea of the entry cottage. It would look like a little house to disguise the entrance to the underground portion of the house. I liked the idea of a modest little cottage concealing the larger home inside it.
We worked out the look of these rooms with extensive notes (in ppt) for each room.
Layout from Nov 2007, featuring the entry cottage and a decent sized courtyard. It also had a lot of small sunrooms… Funny now to look back at this.
By Dec 2007, I had realized that the courtyard wouldn’t work well in our norther climate, and moved it to the south side
By July 2008, we shrunk the courtyard, tilted some rooms (solar angles) and added the start of the rotunda idea. The walls were still straight because I had not yet figured out a roofing plan. I was considering individual square shotcrete domes for each room.
I used my ppt “skills” to record/share our ideas and layouts for each room in a rudimentary, but useful way. We could edit these easily as we tweaked our design.
I really spent the most time thinking about the structure of the house. I was I going to safely hold up all that dirt without spending too much money or having a house that looked like a bunker? I ended up with this idea of a central tower (the rotunda), with site-cast concrete ribs radiating out from it. There would be shotcrete arched vaults between the ribs passing the load to the ribs, which passed the loads to the ground. It was this central “structural umbrella” concept that changed the design from angular concrete block to the more circular layout built with shotcrete. It was somewhat of a Eureka moment for me as I saw it all come together in my head.
From there, I spend few minutes here or there each day for a month researching shapes for the ribs. I ended up looking into the mathematics of natural shapes such as shells or eggs. These had been studied by ancient mathematicians and Renaissance men and there was a lot of information on the web and in books. Since the ribs would need to be cast on site and lifted into place, I was particularly interested in designs that could be drawn in the field with just a piece of wire (or a stick) and a pencil. I tried these shapes (such as the golden egg, a mathematically sacred shape based on the golden ratio) built into arched ribs at many different angles and simulated loading the ribs with an estimated 68000 lbs of load until I eventually settled on a particular orientation of a 2300 year old euclidean 5 point egg design that had the right proportions.
Golden Egg design
“Golden egg” on its side as part of a rib. However, the heights at the ends were not right, so I would need to tilt it up…
Golden egg, 19 degrees tilt, but still not the right proportions…
Golden Egg, 38 degrees, still not right…
I tried a lot of other eggs, the Euclidean 4 point, the Moss Egg, etc. But this Euclidean 5 point egg, tilted at 41 degrees, had the right clearances, proportions and strength…
I created computer simulations for most of the promising candidates and loaded them with the estimated 68000 lbs that I expected they would each need to carry…
Eventually, by the end of 2008, I got into Autodesk Revit where I could CAD up the model in 3D. Now it was getting interesting. We had spent a lot of time discussing each little detail and there was a reason for everything. All the rooms had purpose, even the angles of the windows were designed to line up views thru the house (and even functioned as a solar clock).
An early version in Autodesk Revit, windows are missing, furniture is still sitting outside, but you can get the idea.
At some point, I hit that little button that calculates the square footage. Ouch, 3917 sqft, plus another 1035 sqft for the garage. We could not afford that much house… How had this happened? We had started from the rooms of a 2400 sqft house, but then probably added a few feet with each alteration. We ended up making some drastic cuts to get it back under control.
Our original footprint was much too large, the house had to go on a diet. The purple outline is the original floor area, the white walls are the shrunk down version… At least for a few days… A lot has changed since then.
Then we went out to shop for some land… I will save that story for another day, but the punch line is that the lot we bought had primary access from the south and best views were to the north, so we had to scrap much of what we liked about these these early designs… More on that later.
We started with the long line that Sherri had marked out before the excavation. We tied some masons line between the stakes that she had placed 50ft on either side of the center (the excavation was about 60 ft across). We tied a plumb bob to the mason’s line at the middle point and let it hang into the excavation. The sand was also very soft and rough, so I spent some time flattening the area, especially around the hanging plumb, with my 10” tamper. I then positioned my marked concrete paver (90lbs) centered under the plumb and lined its etched angles up with the mason’s string overhead. Then we setup the builder’s transit over the paver (I finally have that setup process figured out after three rentals). Again, I used the overhead string (and the lines etched on the paver) to orient the transit. It took us about an hour of setup before we placed our first stake, but once we did, the rest went fairly straight forward. Since most of the key points for this design are positioned radially from the center, we just needed the transit for the angles and a measuring tape for the distances. This marked out the centers of the edges, then we offset these stakes by one foot (half the width of the footing) to get the true outer corners. In one corner, we use some Pythagoras (3-4-5 triangle) to square things up. We also put a lot of “extra” stakes in to make the curved shape clearer and topped it off by tying string along the perimeter of the footings. We actually had brought surveyors paint, but it didn’t work well on the sand. 
Hopefully the Excavator will go back and take care of the over-dig without disturbing these stakes or the centerstone marker (paver) too much and we can get to work on the footings. I found out that my footings guy uses a “Total Station” builders transit. It has a computer that does all the trig for you. We will let him stake it out next time. I just need to figure out how to transfer my drawings into the right format.