Foundation System

I have drawn this detail so many times, and never really understood how it was built… until now.

Click to enlarge.
Click to enlarge.

It is a standard foundation detail; one taught in school. However, I learn by experience, so it took building it to finally make sense.

The most confounding part of the detail was how the vertical rebar managed to stay in place, as the concrete footer was poured. It turns out, to be much simpler than I imagined: the concrete is poured, and THEN the pieces of vertical rebar are set into the footers. Fresh concrete is firm enough to hold rebar in place. I for some reason thought that concrete had a similar consistency to water, but its fluidity is incomparable, plus the aggregate in concrete helps keep rebar in place, and as it dries it becomes solid.

Week Two Recap: we dug the trenches, laid the continuous rebar, and placed chairs, spreaders, and vertical grade pins.

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Next, we poured the concrete footer.  This process began by spraying the trenches with water to slow down the concrete dehydration.

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We had a big group of guys there, and we needed every one of them.   Steve was controlling the pump arm; Gato was working the hose. Harvey was shoveling concrete into places the hose couldn’t reach. Bruce and Greg were tamping the concrete down to level. Juan was at the tail end making the surface smooth. I was taking pictures, and my dad was telling us all to “¡Jale´ Jale´!”

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The large concrete pump arm can reach 100’ feet – to the furthest corners – so we didn’t have to fill those trenches manually. The whole footer took us about two hours to pour, including placing the rebar. We were done by 9am.

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Gato and Harvey (the Masons) then went around the perimeter and placed the vertical rebar every 48” to support the CMU (concrete masonry unit) stem walls. They knew exactly where they wanted them.

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That all happened on Friday – end of week two.

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Week Three Recap:

Last week was incredibly productive and once again changed my perspective on the scale of the house. When we cleared the sagebrush I was concerned with the house being too small, and now that the CMU walls are in place, the house is starting to feel large again (the model always felt “big” to me). Last weekend I spoke with another woman, who worked in construction, and she mentioned, “ Throughout a project, certain phases will expand and contract space.” I was comforted to hear it, because so far it has been a wild ride, but apparently not unusual.

On Monday, Harvey and Gato set the “leads,” which are the CMU corners. We started with the corners, because they have to be exactly square and set at the right elevation, as the rest of the wall is dependent upon those being perfect. Harvey is sooooo good at this! His trowel and masons level are extensions of his arms; it is mesmerizing to watch.

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Staged block around perimeter of continuous trench.
Staged block around perimeter of continuous trench.

On Tuesday we filled in the walls. The guys let me lay two blocks – it was extremely difficult, and required ambidexterity. Needless to say, they had to redo my work.

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Almost done!
Almost done!

Wednesday, we had off. I forget why. Probably to let the blocks set.

Thursday, we poured concrete into the cells of the CMU block walls. This didn’t require as many people as the footer, and we used a much smaller hose. It was also a quick job.

Group effort.
Group effort.
Smaller concrete hose on ground.
Smaller concrete hose on ground.

At this stage we had to insert anchor bolts, every 6’ around wall, while the concrete was still wet. The anchor bolt, will anchor the framing to the foundation wall, once we get to that stage in the project.

Triangles drawn on block demarcate anchor bolt placement.
Triangles drawn on block demarcate anchor bolt placement.

And on Friday, Bruce and I had the pleasure of taping 2” rigid foam board to the exterior foundation wall, and then back filling it with dirt. Foam insulation is required by code, and is effective for preventing heat loss through the foundation.

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P.S. What my dad does when he is not being the Boss:

Ed meditatively chopping wood.
Ed meditatively chopping wood.

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