COB & ON: Concrete Pour

A lot has happened since the last post! After having sat in front of the computer for 3 weeks while my finger recovered, I was just itching to get back to the site (and the computer has been terribly unappealing since). Below is an update of the last week and a half of work...

This is what the site looked like during those three long weeks of recovery:

Last Saturday, I was blessed with the presence of my friends Dylan (my sister's neighbor) and Ariel (a student at NC state). We did a pretty good job of transforming the site in the previous photo to the site below. It also took a good chunk of Sunday to finish all the details of the excavation, and get it down far enough below ground level. Dylan and I dug until 11:30 PM on Sunday night, with worklights (and a delivery of pizzas).

This past monday, my first official employee (ever!) showed up. Jeremy will be working with me on most Mondays and Tuesdays over the coming month. He has had a great deal of experience with conventional construction in California, and also has done some strawbale work in Virginia. He convinced me that we should install "batter boards," which is the system of posts and strings that you can see in the photos below:

The whole idea with the system is to locate a level, "square" (meaning perfect 90-degree angles) rectangle. Most people do this before digging the footing trench.

Below is the footing form that Jeremy and I made for holding the poured concrete. The footing is essentially a thick, wide, concrete perimeter that will hold the weight of the house.

Because the ground is sloped, I designed the concrete footing to have two levels (like a terrace, or step). Here is the part of the form where the one level transitions into the other:

I got one load of gravel in my little truck, and then decided that it would be a ridiculous waste of time and gas to drive back and forth to bring the additional loads that I needed. So I ordered a big truck to come dump a big pile of it for me to conveniently take from. The gravel will be used for drainage purposes - underneath the footing, beside the footing, around the retaining wall out near the sidewalk, and so on. Whereas clay expands and seals itself off when it gets wet, gravel creates a whole community of little negative spaces through which water can drain and safely leave the underbelly of a building.

As the house footing project was beginning, I simultaneously decided to take down the retaining wall in the front of the lot (as it was old, poorly crafted, and falling over). I was able to push over all of it just using human power and a 5-foot, steel dig bar. You can see the remains of it up on the lawn.

After knocking down the old, it was time to make space for the new. This was another couple days (and nights) of digging.

This past Tuesday, Jeremy and I began building the form for the retaining wall. Every single retaining wall in this neighborhood was built vertically (and are all seemingly about to fall over any minute), so I decided to design the wall so that it tilted back against the earth at a 15-degree angle. Think about how much easier it would be to push over a wall that's standing in a vertical position, versus trying to push over a wall that's leaning against you. In the first scenario, you just have to tip it enough to let gravity take over. In the latter, you have to overcome gravity just to get it to vertical, and only then will you be able to heave it over. This is the challenge that I am setting for the earth behind the wall.

I continued working on these forms through the week...

It is important to get all of the details very tight and clean, so that I can eventually get the forms back off after the concrete is poured (and reuse the wood). If they aren't built meticulously enough, then concrete can seep out and entomb the wood for all of time with its gray, cold grasp.

Dylan volunteering some form work, in his I'm-going-to-the-moon jacket. The trapezoidal shape of the form around which he is working will be the space in which I will build stairs (probably concrete with brick steps):

The form is ready for concrete (finished the morning of the pour - phew!):

The night before the pour, Dylan and I again got out the worklight, ordered pizza (and beer this time), and set up for a long night of gravel-dumping and rebar-setting. I never ended up getting a great photo of our work, but here is one that my brother-in-law, Doug, took the following day of both Ian and the rebar (the rebar is the steel rod sticking up out of the gravel - it acts like a skeleton inside the concrete, so that if the concrete breaks or shifts with the earth, it still holds together).

My future digging partner in action!

The truck has arrived. It's quite a logistical nightmare to figure out how to pour. It's especially stressful because of timing. The truck can only stay for so long (so that the concrete doesn't set up inside of it). The chute can only reach so far. The truck can only back up so far. And so on...

On the afternoon of the pour, I had more help from Dylan, and also had my friend Danielle out (she's the builder of the two-story cob house that I have featured photos of before), and also my nephew! Doug generously offered to pick up Ian from school to take him on a personal field trip to see the pour. He's a big fan of heavy machinery - diggers, trucks, you name it. Below, Dylan and Danielle are pulling the concrete through the form.

For the second tier of the pad (which the chute couldn't reach), Dylan and I devised a wheelbarrow plan, involving two wheelbarrows and a precarious ramp.

First, the truck would fill the barrow.

Second, the driver would lift the chute (and stop the flow of concrete), and I (or Dylan) would begin pushing the barrow underneath the chute (through a shower of concrete droppings), and up the ramp. By the end of the pour, my hat was covered in concrete, as was my left arm, my shoes, and my whole backside.

And thirdly, we would strategically pour the material out wherever it needed to go (or, in some particularly stressful instances, we would tip the barrow and spill the concrete all over the pad where we didn't want it - you can see one of my spill spots in the photo below, to the left of me).

For the retaining wall pour, I adjusted the chute to the right length and angle, and then the driver was able to slowly drive the truck along the road and pour as he went. Danielle held a sheet of plywood across from the chute the whole way, to re-direct any escaping concrete down into the form (like a really stressful game, almost).

9 yards of concrete later, and the pour is complete!

Today I began to remove the forms, which was very much akin to the feeling of opening christmas presents when I was seven. Tiana, below, is one of the neighborhood kids who have been consistently interested in visiting the site to check on the progress of things.

And the footing after the form has been entirely removed. I was really pleased with how the pour went, despite how rough a start we had (for any number of reasons). I will admit that it was probably the most overwhelming building experience I've ever had (aside from certain teaching experiences), but was very satisfying to get mostly right.