After the excavation, the concrete company poured the footings. They essentially just poured the footings in the hole that was dug. It needed to be a minimum of 30 inches below ground to be below the frost line. Otherwise when the ground freezes during the winter, it would heave the building to and fro. The footings were a minimum of 18 inches wide and 12 inches thick.
A few days after the footings were poured, they formed the foundation wall and then poured the foundation wall. The wall was about 24 inches high so it would be about 6 inches above the ground.
After the foundation wall we had to prepare the ground for the slab. The slab only needs to be 4 inches thick and I don't want to pay for more concrete, so I ordered a bunch of gravel for structural fill to bring it up to grade. My first order of gravel I ordered 5 yards. I must have underestimated by quite a bit, so a couple days later I ordered 6 more yards (the delivery truck holds a maximum of 6 yards). Something was wrong, though, because we got more than twice the amount of gravel on the second order than the first. I told them that, but they insisted they gave me the proper amounts. Oh well. It would be nearly impossible (and highly inconvenient) to prove for about $80-$100. So I dropped it.
In the woodshop portion of the addition I am putting in-floor radiant heat. That meant that it had to be ready for the slab pour. So I ordered several 4'x8' panels of "blueboard." That is 2" thick styrofoam panels meant for insulation. I couldn't believe how sturdy those boards are. I could easily walk on it without it tearing or denting. The foam is to ensure that the heat from the radiant tubes doesn't go into the ground, but instead is directed up toward the room. On top of the blueboard we put some wire mesh (about 10 guage - too thick for wire snippers to cut). We then tied the radiant tubes back and forth all over the wire mesh. The wire mesh is really just meant to hold the tubes in place during the concrete pour. Because the tubes are filled with air, they could float to the surface if not tied down. Then we raised the wire mesh off of the blueboard with some cut pieces of brick. We really want the radiant tubes suspended in the middle of the slab, not the bottom.
The radiant tubing ends in a manifold that was encased in a wooden box in the concrete. None of the copper of the manifold is supposed to touch the concrete because the concrete would corrode the copper. Later I need to hook up the manifold to a pump in the house and an extra hot water heater. Because this is an outside application, I will need to have an anti-freeze solution in the tubing and hot water heater. Some radiant systems just use the hot water from the existing hot water heater, but that doesn't work for outside applications.
As a side note, at work we recently met with someone who built a very nice home on a hill overlooking Salt Lake Valley. The builder has not finished the home. Three weeks ago he promised us that he would have it done in two weeks. (He has been promising this for months, I guess.) The last major thing he has to do is his driveway, and he is putting in radiant heat in the driveway so he doesn't have to shovel the steep 150 foot driveway. He started telling me the costs of putting radiant heat in the driveway. He said it would cost a minimum of $50,000. Good thing I had just priced this out. In fact it would only cost about $15,000, even if you had a pro install it. If he did it himself, it would cost about half that. It was nice to be able to call him out. Unfortunately, the bank will probably own that nice radiant-heat system.
Well the concrete worked out pretty well. We actually has started framing prior to the slab pour, but once the slab was in, it was much easier to work there.
