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.
Response to Rebar and lath for the bedrooms
Alan says:
Simon, this is another excellent update.
It’s good to see your family involved too. Projects like this are what make kids apply their imagination in constructive ways as they get older.
In realtime, have you begun working on finishing the interior yet?
As always, nice work!
Simon says:
Some bits have “interior”. I would say the garage is pretty much complete except for the ridge cap and the bathroom sink/shower. But other sections do not even have a roof yet and I have not begun to bury anything… It is a slow process.
John Boldt says:
looks good. What is the projected date for shotcrete?
Simon says:
The bedroom shotcrete was done last summer… (I am very behind in posting). I will soon be uploading the next segment though. If you want to skip ahead, look up “Home in the Earth” on Facebook. Our next shotcrete days should be in May. We still won’t be finished construction, but we will be able to bury the bedrooms and garage after that.
John Boldt says:
That is really good news. I think many people do not understand just how much work is involved. Of course, if you had unlimited funds and could simply hire people to do everything, it would be done by now. But who has unlimited funds? I do want to thank you for your postings, as I am considering building an earth sheltered home and I have learned a tremendous amount following your posts. Thank you.