Information about design and construction of earth sheltered homes and a journal of my own progress

Rebar and lath for the bedrooms

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Posted on May 6, 2016 by

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.

 

 

Running Septic Lines

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Posted on May 4, 2016 by

We needed to hook up the septic side lines to run from the bedrooms and garage to the main central line coming from under the basement.  The original plan had these running under the house, but the plumber suggested that it would be much easier to run the line outside the house completely…  At some later point, we also decided to run the bedroom electrical along this outside line.  Of course, this all required some digging.  Gota love that nice soft sand.

The Video

Some details

The Stack:

The bedroom septic line had a further run and needed to be below frost depth, so it connected at a lower point on the stack.  Then I connected the garage line at a higher point.  However, I thought it would be a good idea to slope it more and get deeper than I had to…  Some plumbers say that you shouldn’t slope too much because the solids and liquids will separate and you will have clogging problems.  I have done my research and determined that was not true (just a plumbers wives’ tale) so I didn’t mind sloping it more.  However, after making the stack connection with the Y-pipe shown in the video, I decided that I didn’t like the angle of the connection.  Basically, these pipes are designed to connect at closer to perpendicular or maybe 5 degrees off.  My original connection was maybe 20 degrees off.  It was probably sealed, but it didn’t look great and I didn’t want to take any chances.  I ended up cutting off that Y-connection and extending the stack so i could connect at a higher point with less slope.

The Shortcut:

The plumbing and the electrical in the bedroom wing both connect in the laundry room, very close to eachother so they can exit from the same hole and follow the same trench…  However, I didn’t measure conservatively enough and although the electrical cables could reach the panel, I was worried about being a few inches short of making final connections, so we ended up digging a short cut trench for the electrical cables. At least we could still re-use about 2/3rds of the trench.

The Electrical cables:

Earlier, I had experimented with other kinds of cable, running thru conduit. This time I was using cable that was certified to be directly buried.  It was still in conduit where it came out of the garage (because it is not certified to be encased in concrete and because I didn’t want a potential leak above the floor anyway), but then came out of the conduit below the footings level.  I basically wired it according to above ground code with the required depth below the footing and bushings, etc. After burial, it will only further exceed code.

Gallery

Just some pics…

Front Steel Columns

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Posted on April 28, 2016 by

In this segment, we mark and place the front columns and the curved I-beams that form the framework for the entry and green house sections.  Most of the time-lapse footage was lost some how, but I did have some pics…

The video

Surplus Steel

I bought the columns from the surplus steel place in my area.  The cost was low enough that I didn’t mind a few imperfections.  No regrets and I will probably do it again.  I did put tape over the holes to keep wasps from moving in.

Trouble with the Forks

When I bought the skid steer, the guy who sold it to me said he also had a beat up set of old forks that I could have for 200$.  New forks cost 3 or 4 times as much, so I told him to send those with the skid steer even though I hadn’t actually seen them.  At first, I just noticed that the back board was a bit damaged.  After using them, I also noticed that the two forks were actually different thickness (miss-matched set) and had bent slightly differently and I was having trouble holding things level.

We didn’t worry about the back board, but my father and I fixed the “uneven” issue with some torches (and lots of patience) to heat up one of the forks so we could bend it to match the other.

But all that time, I was using the forks to lift heavy things, so I didn’t notice the 3rd issue…  When you apply loads the other way (pushing down on the forks), the locking mechanism is supposed to hold them in place.  However, the top ledge that holds the locking mechanism in place had been slightly stretched upward and increased the tolerance by maybe 1/4th of an inch, and that was enough for the mechanism to actually detach when the load was pushed the other way.

While setting the second I-beam, The beam got hooked on the bent back shield and wouldn’t let me lower the forks.  Since this flipped the load direction, it also shifted the locking mechanism down 1/4th inch relative to the forks and they detached from that top edge.

With the load direction reversed, the forks detached from the skidsteer

Those Forks are a few hundred pounds of heavy steel, so rather than just let them fall off and possibly damage something on the way down, we strapped them to the quick attach mechanism on the skid steer so we could still lower them carefully.

The final fix was to weld 2 pieces of angle iron across the top of the quick attach mechanism to remove the gap so it won’t be unlocked by a reverse load.

Final view. There will be windows under most of those Ibeams and a Front door under the left most one. Earth covered in grass, etc. will be above.

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