There was just enough decent weather left in the season to prep and shotcrete the walls around the perimeter of the central circle. We had to start with the formwork, and since these walls had simple curvature (rather than compound curvature), we decided to use OSB board screwed to vertical steel studs. Of course, rebar was added in and tied. I’ll get into details and lessons learned later in this post… And there is always a gallery of pictures at the end, but first, the timelapse video.
These MarinoWare steel studs I have been experimenting with are a bit of a mixed success. They are great for holding the formwork, rebar, electrical, etc. And I like to think that they provide some reinforcement for the concrete. On the negative side, the shotcrete crew were not always able to properly encase them and possible voids in the walls along these studs probably reduced the wall strength and provided a path for water to channel. I wouldn’t call them a total failure, but I have decided not to use them in this same way for the central tower. Instead, I will brace that formwork from the outside. I will continue to use these studs for the South wall because the design there has these outside the concrete, supporting the rigid insulation formwork.
Screwing into Steel Studs
Pre-drilling would just take too long and it would probably drive you crazy trying to keep the boards aligned to get the screws thru the pre-drilled holes. Self-tapping drill point screws are what you need. They should be long enough to get thru the form materials (3/8th inch OSB in my case) and still bite in nicely to the steel. In places where you put an extra layer of OSB (such as to thicken the joints), you will need an extra 3/8ths of length. Also, to save money, you want to use the shortest and smallest screws that will work. Finally, the key thing is the head… I recommend the Hex-Washer-Head because it will be held securely by your driver without any slippage or cam outs. Do not buy Phillips head screws, you will seriously regret it.
Personally, I ended up mostly using TEKs #10 x 1 in. Zinc Plated Hex-Washer-Head Self Tapping Drill Point Screws that cost about 4 cents each. If you can get them in bulk, you can probably reduce the price to half that.
Plumb and Braced
For some reason, the camera kept moving on to the next area before we would complete the important job of plumbing and bracing each section of wall. However, that step was important and worth a small section here. The walls had some natural stability because of the curvature, but we still needed to brace them against the force and vibration of the shotcrete and they were not always naturally plumb. On dirt, we could just brace with a 2×2 or 2×4, screwed to a block on the wall and then screwed to a stake. However, for most of this job, we had to brace on the concrete deck and didn’t want to attach the bracing to the deck and risk damaging our radiant tubing… The solution was to place a board on the deck, screw the diagonal brace to that, and also screw a horizontal brace and tie it back into the wall. This worked pretty well.
In one location, the wall was out of plumb and took some serious pulling to try and force it plumb. Some combination of the boards, studs, and rebar was fighting against us. I ended up just using a strap and a come-along to pull it. Part of that strap is still embedded in the concrete wall, but at least it is plumb.
I get a lot of negative comments from people saying that it is “against code” to weld rebar. In reality, the building code has about 85 pages devoted to welding rebar. The code talks about what types of Rebar you can weld (mine has a little “w” on it to indicate that it is weldable), diameters (most welding rules don’t kick in until #7), what types of welds you can do (butt joints are not acceptable), pre-heating, exceptions based on engineering approval, etc. I was going to get into it a bit here, but it is probably better to just suggest you read up on it yourself.
While I agree that the heat treatment that comes from welding does influence the ductility and other material properties of the steel, in certain situations (some of my situations), it does make things much better. I know what I am doing, everything is inspected, no need to worry about it.
Here is where we put some of the pics we took during this period…
from time to time, I’ll just take a photo of my screen so I can have the measurements handy in my phone… Some times it is faster than trying to transfer a proper screen shot…
The Hex Head screws are much much better
For us, this build is pretty focused work. But while we are out there, the kids will often find time to play or read a book in some odd place.
Working on the side wall in the guest room. We had this one shot from the kitchen across the basement stairs.
Me setting up the camera in the kitchen…
I think I may have kept too many pics of David setting up the camera…
Sherri gets goofy some times…
Joe working on the dining room wall.
David Setting up the camera. He likes this job.
Here my father is working on the wood forms and my mother is tying rebar… Probably not the retirement they expected.
Sliding the rebar into the short wall section.
For this little side wall, we put in all the rebar pieces and then cut them down to size.
David setting up the camera for a shot
David was climbing around on the tower steel and took this interesting pic of Hunter walking thru the site.
Another shot of the playroom apse before it got started. You can see all the steel arches leaning against the rigid insulation in the background.
I separate out these jobs, but they often overlap. On this day, I was working (For ANSYS inc) from the site because the stucco guys were working on the garage. In the evening, I probably switched to welding the playroom apse or something like that.
I originally set everything up around this middle post, then I welded the outer edges in place.
To form the apse, I had to weld the thicker rolled steel arches to the thinner galvanized steel studs… It doesn’t have to hold forever, just long enough to be encased in concrete. It took a little practice to be able to weld the different materials reliably. I did little patches like this ever few inches along each edge where they met.
This looks like it was from my timelapse, but the rest of the video was lost… It happens sometimes.
This is one of those pics that happens when your 10 year old is just walking around with a camera.
Welding the rebar
apse steel ready
Apse steel from above
Outside of the guest-room wall. We shot the walls from the outside to try and avoid messing up the deck.
The inside of the guest room forms.
We try to avoid it, but occationally we are all working within a very narrow distance of eachother…
For some reason, Hunter likes to pose for the timelapse… Just while he is walking by in the middle of the shoot. The easter egg photos are mine now.
Friends playing while their parents helped out…
The north side, ready to shotcrete.
This gap between the back of the kitchen wall and the Quonset hut will be filled with a lot of earth.
This pic is trying to show that I cut away the fox blocks and drilled the horizontal rebar into that wall to tie everything together structurally.
The connection between the guest room wall and the mudroom…
Underground homes come in all shapes and styles and budgets… Here is a very nice example designed by Scott Allen Architecture and built into the side of a cliff in the harbor…
This is not what most people think of when they hear “underground house”…
If the picture above doesn’t look much like an underground house, let’s try looking at it from the front. Imagine pulling up this driveway and just seeing this glass box instead of a house…
The “front door” of the Cliff house… The grass is above the living area below.
Here is another view showing access from the front yard down to the courtyard below…
This is a “sunken” courtyard, at least relative to the front yard.
You may need to go back to the first pic to see how these areas all fit together. My younger son couldn’t wrap his head around it. He kept saying, “so they are just pretending it is underground, but its not, right?” It is really beautiful home. If you want to see more, check out the architects site.
Even with all that glass, I bet the concrete structure and protection of the cliff keeps things relatively calm inside during a storm.
I am guessing they were not as focused on efficiency as I am, but still, it is a really cool example of the flexibility of earth sheltered homes.
This past year was different to the previous ones because we finally started bringing in other professionals to share the plan with. Confessing what I planned to do made it all more real. In exchange for bringing people in, I had to relinquish some control, which was also a bit of a stress for me. But I have to admit that having someone else do all the work of drawing the elevation views did free me up to think about details…
I some times think of it as “paying for friends to talk about stuff you like”, kind of sad and it didn’t really work out as collaboratively as I had hoped. And since I am paying most of them, I could never really trust their affirmation that I was sane ;^).
The plan had been to start construction during Q3, 2012. It didn’t work out, primarily due to delays with the engineer (who slowed down the architect because he was waiting for the architect).
If those delays had a silver lining, it was that they gave us more time to figure things out and time to set aside even more money for the build. It also gave me time to meet Scott who was building his own earth shelter near Battle Creek and I learned some valuable things there. I guess I will just keep right on learning things and improving the design, but at some point, I would like to start building and let the mistakes fall where they may. My wife and I just had a little discussion about what could put off our plans to start in 2013… That list of hurdles may be a good New Years post. In the mean time, here is our year end update…
I went to the architects last April with a pretty complete idea of what I wanted to build. I wanted help with the construction drawings and I wanted to get some perspective and collaboration. The drawings are coming, and I certainly appreciate how delegating that task has freed up my time for details. Collaboration (which I define as “talking thru ideas to come up with a better than either of us would have come up on our own) was elusive, but they did add a few good features to improve the design.
For instance, I had originally designed the front of the house with three concrete sunshades, but the architect combined them into a single one that really helped unify the front of the house. He also improved the way the hall passed the sun room for better flow, adjusted the extent of the two smaller vaults for better rhythm and a few other things. Some times, these changes caused problems that were left un-fixed… For instance, the combination of changing the way the hall went thru the sun room and adjusting the location for the end of the vault over the sun-room left us with a very undefined ceiling and load paths that hung in mid air. I asked them about that for months without an answer.
Mid November, my architect mentioned that he thought his assistant had taken care of all our complaints and question and they were almost done… I didn’t think so, so I went thru my emails (over 100 of them) and collected all the un-resolved issues into a ppt slide deck 21 slides long. I mercifully broke things up so that each slide focused on only one sheet of the drawing.
These are sketches of the storm room that I got from the architect. He never explained any of them to me (no collaboration)
Some of the slides were short, such as the slide for the title sheet that simply pointed out an incorrect note about the foundations… but other slides were quite long and detailed and included many points and drawings about various concerns that I had been waiting for answers to… The architects took it pretty well, but over a month later, they are still working their way thru the corrections (and have not actually fixed that silly note on the title sheet) and have not gotten back to me on even one third of the questions.
The design development for the storm room never really got anywhere although the architect did send me a few sketches. Perhaps these designs were not what I was looking for, or perhaps I was just looking for collaboration (an interactive back and forth exchange), but I didn’t like any of them. I wanted something that would unify the design of the house, and I didn’t think any of these ideas did that… Eventually this December, I sat down with my pencil crayons and solved a number of these problems so I could just present my solutions to the architects so we could move forward.
Our architect’s assistant also drew up some quick 3D sketches. We ruled them out for various reasons.
My wife and I met with the architect and his assistant the Friday before Christmas. We showed our latest sketches for the “storm room” (the tower on the top of the house that will let us view 360 degrees of weather), and the structure for the entry and sun room (aka “green house”, but that would be hyperbole). We also discussed our new window list and answered questions about the HVAC layout (ventilation actually). While there, the assistant quickly modeled up something in 3D CAD (rhino3D) for the storm room and also showed us an interesting 3D model of the entry way in order to propose a new feature. We liked his suggestion and are hopeful that the plans will actually be completed within a month or two, at least with the architect.
I am quite a bit more concerned about the engineer since we haven’t heard anything from him in over 7 weeks. I will check up on his progress in early January. The biggest mistake with the engineer was expecting too much collaboration instead of just validation. I am sure it was frustrating for him since “collaboration” is not easy to estimate. Now that I am neck deep, I wish I had been more specific about what I expected him to bring to the team, and I would have expected a lower price tag with that reduced uncertainty.
This past month, we meet again with Marvin windows and Pella windows. Again, perhaps collaboration is a bit too much to expect from a window company… But that really is what we wanted. We originally planned on Marvin because they were one of the few American window companies that produced low-E glass with high solar heat gain. They also had “push out” casement windows that I preferred to the crank outs… And they had very wide casement windows (possible due to their aluminum extrusion construction), french windows, more size flexibility, etc. I totally ignored Pella for my first round, along with other “big box” brands.
Sherri and I never really liked the Marvin reps in our area. Some never did get back to us with a quote (even though I visited several times) and the ones who did were a bit too pushy. We got pretty far into the process with one location (that will remain nameless to protect the guilty). Maybe it was just a generational thing, but we didn’t like their sales technique or how they talked to us without giving us useful information. They used lots of phrases like “of course you want to buy the best”… When I asked about how the features of a window affected the price, they kept saying they “hardly matter”. For instance, I wanted to understand the difference between the cost of a round top casement and a regular casement mulled with a fixed arch top transom… I knew the opening round top window would be more, but I wanted to understand how much more. They went on and on about how I certainly wouldn’t want to even consider the fixed transom option, how it wouldn’t go with the style of the house and that the round top wouldn’t be much more expensive anyway… Well a few days later when I finally got the price for each, I found the round-top was quite a lot more expensive. Again, perhaps it was just their age, but they always acted like getting a price on anything would be a huge amount of effort and I had to come in to see them because it was difficult to get the quotes into an email…
In contrast, the Pella rep was very likable. She understood that we wanted to understand the pricing so we could make good decisions. She also joked that she was a part time marriage counselor a roll we found she was pretty good at. Every time we wanted to know a price for something, she would just enter it into her computer various different ways so we could see the effect. This was enormously helpful. She built the window list on her computer right in front of us. We could see the options she was entering and ask her about adjustments, etc. For instance, while the Marvin rep had hardly said anything about Tempered glass or given us the rules for it, the Pella rep explained all the rules (so we could design around them) and showed us the resulting price difference. When she didn’t know something, she was frank with us and took a note for later…
Some of the windows from our window schedule. The shape of W3 and the width of W4 were only available from Marvin
The quotes we had received from Marvin had ruled out the push out casements (double the price), along with French casements (quadruple the price). We also found out that Pella now had the passive solar gain glass that we wanted. We were down to a couple “special” windows forcing us into Pella… These were a half arch top (W3) and its neighboring 40″ wide casement (W4) (Pella topped out at 35″ wide). Not only would we have to pay the much higher Marvin price for these two windows (x2 for symmetry), but we would need to buy all the windows from Marvin (even the ordinary ones) and it actually more than doubled the overall cost of the window package. Sherri and I liked the look of W3, it was one of the enhancements the architect added when he put the wide sunshade across the front of the house, but it wasn’t worth adding more than $30K to the cost of the home. Neither was having W4 be 40 inches instead of 35.
Here is the window arrangement for the front of the house. W3 tucks under the sunshade. It is really a single window with a faux mull (to save money). We decided to save even more money by making it a rectangle. W4, the casement next to W3, would lose 7 inches of width.
We decided to make the switch to Pella. We worked with the rep to adjust our window schedule to standard Pella sizes and tool that list into the architect. One non “brand” change we made was for the 3 part windows at the ends of the vaults (W12)… Each of the 3 sections costs the same price as a full width window of the same overall area, but the wall curvature forced us to break it into 3 sections. The W12 combo of 3 windows was nearly $4K; since there were 6 of these, that would add up to a big headache. We decided to reduce the height and have only the single central arch top for about 1/4 the price.
A CAD drawing of the rib, done by the engineer.
Another sourcing issue was finding a company to handle my precast architectural ribs. I contacted a bunch of companies, but the first round were all concerned that they didn’t have the skill to handle it. They were mostly experienced with highway construction or sewer components. They did point me toward some companies that could help (the key was to include the work “architectural” in my search for “precast concrete”), but I have not received quotes from those companies yet.
The website development is going slow (no blog posts in more than 7 weeks doesn’t help). I did some work on some pages (such as this inspiring one on urinals ;^)). At this point, we have had nearly 7500 visitors from all over the world (check out the map on the right) with a max of 127 hits on Nov 14th.
For some reason, my comment system has stopped working on the home page. I will try to figure that out, but it looks like you can still leave comments if you browse to the post thru the tree on the right.
On the Houzz site, they did a bit on Hobbit homes that I thought I should post a link to…
Oh yea, if you are reading this in your email, that doesn’t work as well as clicking the link and reading it on the website… You get the pictures that way. ;^) I also tend make a bunch of typo’s on my first draft that I catch 10 seconds after I post. The live link includes any updates…
And now the part you have all been waiting for… A gallery of eye candy.
I found this geodesic concrete dome on tinyhouseblog.com, a fun little website. I think shotcrete over rebar is easier, but this seems fun.
This is part way thru construction, you can find more pics on the site, but I thought it looked better here than after they added the shingles.
Malcolm Wells talked about using copper pipe for a trellis, but this is one of the few examples I could find a picture of.
Pella now has “Natural Sun” glass that is perfect for what I need, but it is only on the price list for Canada. Clearly, the weather crosses the border into Michigan, but I had to special order to get this kind of glass.
I like these “kitchen garage” ideas from houzz.com
Hide away ideas from Houzz
Now this is just fun.
I like the bump on this porch and how it accommodates the arch top door… This may be something to consider for my design.
A full passive solar roof
This copper roof gives a hint for how we will do the storm room… I may like to do copper diamond shingles on 2 of the six sides…
Radiused copper seam roof under construction…
We are looking into copper roofs, and where better to find inspiration than the copper architecture awards
I got this from the http://thecarpentryway.blogspot.com
I like reticulated ceilings. I got this from http://thecarpentryway.blogspot.com
After spending a couple days working on our storm room roof design, we needed to see something like this to feel that ours was relatively normal.
Sherri and I are looking for front doors that go with copper roofs… We liked the style of this one.
Just a cool cave house… Not the same as earth sheltered, but we appreciate it anyway.
Thanks to the new Hobbit movie, earth sheltered homes are now available in lego…
I recall this was in northern Europe, but I can’t find its source right now… Not really earth sheltered, but rather plant covered.
I liked this a lot. Maybe along the back wall of the living room.
Just thought this thing was cool, forgot where I got it.
For more precise and simple setup of the rebar, I will use precision curved steel tubes. I plan to use something like these cheap (<5$) scaffold bases to hold it all up.
I put this at the bottom so few will find it, but I here by resolve to create more, but much much shorter, posts for 2013 ;^)