A Shed Foundation

Tuesday evening it was clear that the bees were settling down, and Wednesday they had completely stopped buzzing angrily around where their hives used to be and were back at work. There was a bit of a heat wave in effect but we decided to press on and work on the shed foundation, anyway. It would have been better to wait until the weather cooled down but we had a number of other scheduling things that made that not work as well.

Foundation laid out

Noel assembled the form, then we moved it into place, squared it, leveled it, and secured it with the stakes. Then we dug out the area of the footings so we could install anchor bolts.

The sprinkler is in the photo because after all that, I ran the sprinkler to settle loose dirt and also give us damp ground to work on. The sand we have here in Alameda becomes loose, fine sand when it's completely dry, which is a major pain.

Foundation formwork with reinforcing mesh

In the morning, I laid down plastic and used some dobies to tie the reinforcing mesh into place. There's no actual requirement for a slab like this to be reinforced, but I think it's a good idea, and especially because it was a really hot day so the concrete was going to be a pain to deal with, anyway (this os foreshadowing).

Noel running the concrete mixer

Noel had a meeting in the morning but after that was over we got to work. I set up the patio umbrella to shade him, and then moved it around all day. That little bit of extra shade makes a huge difference.

bees bearding

It was a really hot day. The bees were bearding on Hive A. The weather station says it hit 92F (33C), which was higher than we expected it to be. And of course we were outside working in it all day long.

And it messed up working with the concrete. See, concrete cures by hydrating: undergoing a chemical process that takes in water and forms the structures that make it strong. But if it's too hot, not only does that make the chemical reaction speed up, but it tends to just dry the concrete, so it doesn't have enough water to fully react. Combine that with us just working slower because we are older now, and we had a bit of a hellish day. Fortunately a couple neighbors came over at different intervals to help us out.

The worst slab I've ever made

And I will freely admit that the resulting slab, while perfectly serviceable for our purposes, is the worst concrete slab -- no, the worst anything made of concrete, and that includes some experimental concrete castings from college -- that I've ever made. It is terrible. That back corner there was the first part we placed and it has what is probably a bad cold joint between it and the rest of the slab. The surface is uneven. The whole thing is a mess. Thank goodness there's mesh reinforcement or it would just fall apart.

We made the decision, after working on the slab for a while, to finish it off with self-leveling concrete, and we'll do that next week. That'll give us a decent floor surface, which will be a good thing in a shed.

(Note to self: for larger concrete projects, no matter how handy the concrete mixer is, it makes more sense to order delivered concrete with a pump than to mix your own. Never do this again.)

posted by ayse on 06/17/21