Last year, we got started on the steel structure. This year (2016), we got all the rebar and lath up in preparation for shotcrete. First, the video… Then some info, but mostly a larger picture gallery than usual.
The Video
Details
Statistics
This process took from 2016-05-05 to 2016-07-26, so nearly 12 weeks of the calendar. Of course we also worked on other things during that time (such as the garage which will be a separate video). Specific to this bedroom wing, we worked (at least for a couple hours) on 26 different days. The time-lapse camera (which I ran pretty faithfully) recorded 77,653 images. At one every 5 seconds, that means it was running for 388k seconds, or 107 hours. If we divided that into 8 hour days, it comes to about 13.5 days. About half the time, I was there by myself, 1/4 of the time with Sherri, and the last quarter Sherri and I had other help (Hunter, John, Bonnie, Joe & Jessica (my parents), Dan, Ethan and the plumbers).
If I had turned all 77,653 images into video at 29.97 frames per second, it would have been a little over 43 minutes of video. I edited that down to under 10 minutes (less than 1/4). In some cases, I edited out scenes, in others (such as that last interior wall), I just ran the speed of the video up to x900. You are welcome ;^)
Rebar Chairs
We added rebar chairs to stiffen up the assembly and prevent “bounce”.
It is important to leave some space between the rebar and the lath for the concrete to completely encase the rebar. To achieve this, we made sure to tie the lath on loosely (leave room for a couple fingers). this works pretty well for the roof because the weight of the concrete will push the lath down and away from the rebar, but no further than the wire ties. However, in the walls, the concrete can “bounce” the lath and then fall off the wall. After seeing my setup, the shotcrete guy asked me to stiffen up the walls by adding rebar chairs where the lath was bouncy… I had these chairs left over from the quad deck floor and they worked perfectly.
Welding
Welding was great because it really stiffens up the assembly so you can climb it without fear… and it actually doesn’t take much longer than tying. In many cases, I just tied enough to keep the bars in place and pull any wide intersections close enough to weld. Then I would just weld the rest of the connections much faster than I could have tied them.
The downside to welding is that the heat can actually change the properties of the steel and make it more brittle if you try to bend against the weld… However, in my case, the welds are really just there to keep the steel in place long enough to pour the concrete. After that, it is really the concrete that keeps the steel together (and vice versa). My welds are intentionally shallow, just enough to tack the pieces together without significantly weakening the rebar.
You may find some places have building codes against welding rebar, but if you read them more carefully, they are really talking about cleaning that surface crud off the steel. You get that sort of thing with arc welding, but not with the MIG welder that I use. But in any case, there are no such rules for residential construction where I am building.
Curving Rebar
When you curve rebar, it is always trickier to curve the first and last couple feet. But the middle curves pretty easily. So, I usually curve the full 20 ft long pieces and then cut the nice continuous curve into as many pieces as I can get. If the piece has a 5 ft straight wall before the curve, then I just start curving the rebar 5 ft from the end. I usually start by “over curving” the steel a little bit and then straighten it out to get the final radius that I want.
Gallery
Here is a gallery of pics. Some are just as people started or moved the go pro time lapse camera. Others are just candid pics that went by too fast in the timelapse. There are also occasional cell phone pics in there also. Thanks to everyone who came out to help.
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Photo op after getting the windows in.
A view of the top of the apse after adding the rebar.
Hard to see because it is backlit, but humming birds and butterflies kept getting stuck inside the lath.
The top of one of the interior walls
After getting the first rooms studs in place.
How the bedroom wall studs were attached to the tube steel. The angle cut across the stud was so my drill could reach those screws.
This is the connection for the end of the hall. In this case, the studs were under the tube steel, so the connection was a little different.
A close up view so you can see the stud with the rebar passing thru it and the lath and fabric attached.
Michael reading in his room.
While out there, Dan did some heavier welding also. Here you can see he is pretty happy with the weld.
Here David is setting up the Camera after changing the battery.
Climbing up to get the camera…
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Some times we would turn on the camera and then move it. It would get these odd pics along the way.
Some times we would turn on the camera and then move it. It would get these odd pics along the way.
It took us a while to figure out the first skylight frame, so we were pretty proud of it when we were done.
Hunter checking out the camera… Did I mention that it is a wide angle lens… Not good to get this close ;^)
Putting on the last board and we decided to pose for the timelapse.
After adding the first set of OSB boards. The neighbors must have really been wondering.
After adding the screws from the inside of the skylight, hunter would drop out the bottom… But this time, I took away the ladder.
Here I am holding the boards up on the outside while hunter is inside putting in the screws. This was so I could strip the boards out after the concrete sets.
Michael up in one of the skylights.
Kids just doing their thing.
This shows two skylight towers. On the one, I aligned the fan box with the angle of the tower, and the other I leveled with the ground. Not sure which will look better.
This white tube will allow me to draw the hot air from the top of the skylight back into the house.
View from below so you can see how the rebar is connected to the rest of the structure.
Another view of the skylight curb
The box on the side is for the bathroom fan. It exhausts up thru the white pipe and out.
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David found this 11 inch spotted newt… The largest I have ever seen.
Hunter messing around with the camera. These pics are in the time lapse, but they go by fast.
Sherri all tangled up and not looking like it is fun anymore.
All tangled up.
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David getting into the time lapse shot.
Michael getting into the time lapse.
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Michael and I put up the last section of lath, but first I decided to tilt the camera up.
Putting up the last section of lath.
A view of the all after all the lath was in place.
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At this point, we just had one more skylight to rebar.
This is the plumbing for the master bath side. It looks more straight forward than the boys room because the toilet was closer to the exit.
Rough plumbing for the boys bathroom. The pressure tester is on this end for the inspection.
This is the ceiling box for one of the bedrooms. Later we brought the wire in thru the blue ENT tube and connected the ground to the green screw.
We added rebar chairs to stiffen up the assembly and prevent “bounce”.
Our earth sheltered home relies on thin shell concrete to support the earth loads. I do know of large earth sheltered homes with >50 ft domes made of thin reinforced concrete less than an inch thick, but that sort of precision is difficult. My vaults are relatively small (<15 ft across), but will be 6 to 8 inches thick of very strong (>8000 psi) shotcrete. Once that shotcrete has set, it will be very strong, but before it sets, it is very heavy and needs to be supported.
Rather than build a separate frame to support the structure which will later need to be removed, I am embedding a rebar skeleton within the structure that will support it while it cures and then reinforce it for the next few hundred years until its final job is making it very difficult for someone to tear down.
The #4 rebar is spaced 12 inches apart (horizontal and vertical), tied and then welded (mainly because my family is climbing all over it). We then use metal lath on the inside, tied to the rebar, to catch the externally applied shotcrete.
You can see how the shotcrete was done on the basement level in this old post. Due to the mess of shotcrete passing thru the metal lath in our basement, we have decided to add an additional layer of fine fiberglass screening to the bedroom. The fiberglass still needs to be backed by the stronger metal lath, but it should prevent much more (probably all) of the shotcrete from passing thru.
The video
The schedule
I don’t want to go back and look at my gantt chart (schedule) to remember how long this process of rebar and lath for the bedroom wing was supposed to take. Actually, I don’t even think it is taking much longer than I estimated. The real problem is that I work full time (and even spent 2 weeks traveling to Germany for work) and there were other important things to work on (the electrical service entrance, ribs and quad deck floors all took more of my time then expected, those videos will be compiled sooner or later), so I just didn’t get to put enough time into this frame.
Of course, I wanted to push thru and try to get shotcrete up before winter, but then I got thinking about all the other things I had to do first, such as install the electrical conduit and build forms for the skylight curbs, and I decided I had best take my time and do it right.
Strategically, I also decided that if I focused on the electrical and garage instead, it would give me an enclosed workshop space to work on those skylight curbs and other forms over the winter and I would be in a better position to proceed in the spring. Hopefully, that works out as planned.
The Side Stories
Zack
Zack (the teen I met thru the high-school guidance councilor) has been helping me off-and-on for a few months now. Zack has many siblings, mostly little girls, but a couple times he has mentioned that he has an older brother named “Will” that would like to help. Now that we are tying rebar, there is as much work as they can handle, so I told him he could bring his brother. It turned out that Will couldn’t make it, but Zack said he would bring another brother. He didn’t give the name, so I told my wife, Sherri, that I would guess it. I figured they were going for late letters in the Alphabet because they already had a “Will” and a “Zack”, so I predicted that they would use a “Y” or “X” for the next brother. I couldn’t think of very many names that began with those letters, and figured that Yuri was unlikely (in our Dutch/German area), but since they went with Zack, I bet my wife that his brothers name would be Xavier… I was right.
Rotating Mount
Sorry if that rotating scene made anyone sick. At first, I thought those rotating scenes were pretty cool, but I may have run the speed up a bit too high in the final edit. I can’t promise not to do it again because I ended up using that mount a few more times to film scenes for upcoming videos ;^). The mount was basically just an Ikea cooking timer that I added a 1/4-20 nut to the bottom (to fit my camera tripod) and a spare go-pro mount to the top. It makes one full turn per hour. This is the Youtube video that I followed (roughly) to make it. It cost less than $7.
Shock value?
There is one sequence in the video where Michael (my 9 year old) is climbing all over the outside of the master bedroom vault. Moments later, Sherri is doing the same thing to tighten all the wires (note her clearly “Egyptian” stance). Anyway, I thought this would freak out my mother-in-law pretty well, and I kind’a like doing that from time to time, so I rushed that clip thru a mini production and put it up on the Facebook site (which you can join up on the right side of this page). To my disappointment, it didn’t surprise her at all. She either didn’t think it was very high or dangerous or she is getting quite used to Sherri doing all sorts of crazy things to build this house. Oh well.
Generator
My generator was on the fritz a bit in the middle of all this and there were several weekends where it would only start on the rare occasion. It started often enough that I didn’t want to spend hundreds of dollars to replace it, but rarely enough that it really killed efforts to get this rebar up and kept shifting me to other jobs that didn’t require electricity. Eventually, we decided that enough was enough and got a new generator. Of course, we got a bigger one. Suddenly my welder has a lot more power and I can weld that rebar much more quickly, so woo hoo. Anyone want to buy a used generator with a mystery starting problem?
The Gallery
Just some pics and timelapse stills from this portion of the build.
