Tuesday, July 1, 2014

All about rebar

Those familiar metal rods are chiefly unseen, but they are everywhere. How they get into the hidden world underneath walls and floors and foundations has always been mostly a mystery to me. I've learned a lot about the process watching Adorno prep the site for the first concrete pour. It's cool enough to share.

Monday I spent 5-6 hours at the site waiting on Comcast. Good news is: I got some good sun (it was really hot up there) and we now have Internet, and since PG&E came today, we now have permanent Internet. I also got to watch Adorno build the infrastructure that will be hidden inside the walls of my house.

Here's how the north Salon wall looked Monday morning:

Here's what it looked like Monday afternoon when I left the job site:

A lot of rebar appeared. The rebar is delivered in a single length; in this case, we got 2 thicknesses, #19 and #25, which is a whopping 1" in diameter, unusual for a residential site.

All of that rebar has to be bent to conform to the shapes of the concrete that they will pour. They also bend it at junctions to create strength at the corners. How do they bend it? Because the whole intention behind this steel rod is that it doesn't bend! Well, they have a machine for that. From what I understand, it used to be a hand-crank, which limited the size of rebar that could be bent. Today we don't have any such restrictions, because the rebar-bending machine is powered by a super-strong motor. Here's the Last Great Rebar-Bender, next to a power-saw rebar cutting tool:

The rebar is placed in the groove between the fixed disk and the movable disk. It is adjusted according to a measurement taken at the base of the fixed disk:

Then you just hit the button (on the far side of this photo) and that killer low-torque motor bends the rebar into a pre-set adjustable angle:

So how does this formed rebar get placed? Here's a good illustration. These guys are laying up the vertical rebar that will reinforce the north wall of the salon. They start by standing up a piece of rebar and leveling it. The guy below holds the rebar with a hand-leveler to make sure it is vertical.

Then the guy at the top places a cube of lightweight concrete with 2 wires sticking out of one side (they come in 6x6 blocks that break apart) with a screw through the outside of the form that he secures to the rebar to act as a spacer for the rebar:

Once he has the bar properly spaced, then he drills another hole through the plywood form and threads a bolt that ends in 2 wires, which he uses to position the rebar so it doesn't move from side to side:

Then he moves on to the next one!

I am fascinated by the precision of the Adorno crew. These guys use lasers, tapes, plumb lines, levels, and all kinds of other instruments of precision, but I watched them over and over again just do this by instinct and eyeball. Look at the wonderful symmetry of the rebar that will form the footing beneath the south dining room wall:

Today they started the curved ramp that will climb 3'8" from the front entry into the public space of the house:

Here's a composite of that curved footing, which is figured geometrically off a single point on the south patio wall:

Lindy was at the site today to do a plan check on several different spots, and Edgar from Adorno measured this one off for us while we watched. It was right on. And the crew just kept working:

This is how it looked when I left:

The Adorno excavation duo was clearing out the pre-existing foundation in the garage. Those chunks of concrete have been there, solid and unmoving, for more than 50 years:

Now they're just like the ruins of Ozymandias:

This is a short week with the Independence Day holiday. We're supposed to get a long-term schedule by Thursday. At present, our finish date is still April 15, 2015.

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