Tag Archives: Electrical

Cutting a side door in the Quonset Hut


Posted on November 24, 2016 by


Back when we did the shotcrete on the Quonset hut, we bucked out a side door between the garage and the mudroom.  Leaving the Quonset intact was important because we did not want to weaken the Quonset structure before adding the wet concrete load.  However, the buck keeping the concrete off this section meant we could cut it out and make a doorway without needing a big concrete saw.  Well, now with the mudroom roof on, it is time to punch the door thru the side of the Quonset.

This segment also covers putting the lights up on the front of the garage.

The Video


The Gallery

Another round of shotcrete forms


Posted on October 15, 2016 by

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.

The Video

Extra bits

Steel Studs

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.

Welding Rebar

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.

The Gallery

Here is where we put some of the pics we took during this period…


Rebar and lath for the bedrooms


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



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 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.


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.