The Video:
My time-lapse camera is pretty basic and has a manual focus. I had it set to 8ft instead of ∞. Easy mistake ;^). But here is the slightly out of focus video anyway.
The Story:
I was not able to be on site when the crew setup the formwork and rebar for the garage slab. When I did see it, I realized it would need to be redone. Engineering had been done by 2 different engineers… The first was the engineer that I had hired to do the entire project. He specified rebar every 24 inches across the slab. The engineer from SteelMaster specified 6×6 WWR (welded wire reinforcement). I decided to do both. The guys who assembled the footings were only looking at one of the drawings, so they just put down the WWR. In addition to adding rebar, I wanted to add a vapor barrier, rigid insulation and radiant floor pex also…
First, I waited for the plumbers to come and do their work roughing in the garage bathroom. While they were working, I removed the large sheets of welded wire reinforcing and bent 40 peices of repar to put into place. After the plumbers were done their work, I tried laying it all out myself. However, I soon realized that positioning 16×8 ft sheets of welded wire is really a two man job. I decided to phone a friend. Aaron was willing to give me a hand early Saturday morning.
We started by excavating away a couple inches of sand in the areas where we planned to place the rigid insulation. At nearly 27$ per sheet, I didn’t want to insulate the whole slab, but I did want warmer feet in the bathroom and workshop areas.
We cut and laid the insulation carefully around the plumbing for the bathroom. And then in an “L” shape where my workbench would be…
Then we unrolled a 20ft wide sheet of 6mil poly to use as a vapor barrier under the slab and under the footing all the way around. Here, we are lifting the rebar in the footing to get the plastic underneath it.
The poly sheet was 20’ wide, so we had to do this in two overlapping pieces… Which Aaron taped together.
Initially, we had rebar chairs down the middle, but they were too tall so we had to remove them later.
I measured out and marked the 24 inch intervals for the rebar using surveyors paint.
Then we laid the rebar, using small bits of insulation as spacers. We put the 6×6 WWR on top of that.
Lastly, I brought out some pex pipe for future radiant floor heating… The pex was much longer than I needed for the bathroom, so I made a last minute decision to swing a loop out past my workbench… I secured it to the Welded Wire Reinforcement ever few feet.
The last thing that needed fixing was the wooden board that had been put in place as a keyway for the quonset hut. It had been installed too shallow and had been put in the wrong place (even though I had clearly marked where it should go). We decided to let the experts fix that mistake on the day of the pour.
The Mistakes
- Perhaps I should have excavated a bit more before placing the rigid insulation. It seemed OK at the time, but after adding spacers, rebar, WWR and radiant tubing, I wished I had it an inch deeper.
- I may regret adding the pex loop thru the shop… It may end up making it difficult for me to heat that bathroom adequately without also wasting heat in the shop.
- I only tied off the pex every few feet. But later, when we added the concrete, many sections floated to the surface. The crew pushed it back down again, but then later they didn’t want to cross cut the back half of the shop. Of course, cracks formed along where the PEX tube was too close to the surface.