Foundation Insulation, Temporary Power, and Underground Plumbing Phase I

Dad came up this morning and helped me install foamboard insulation inside the foundation wall everywhere except the two elevator shaft walls, where the insulation goes on the outside so it doesn't interfere with the 12" pit. Stock and Colonial both wanted $35 for a 2" 4'x8' sheet of R10 foamboard, but I got these for $19 at Home Depot.

It was so windy this morning that when I tried to load the foamboard into the van, the wind caught one of them and snapped it in half. I decided to cut them into thirds inside the garage, then take the smaller, more manageable pieces over. The tallest foundation walls were supposed to be 30", so 32" should give us a margin for error, as well as a couple inches to snap off after we scored them along the top of the wall. The form ties sticking out of the walls were pretty easy to just punch through the foam, and held the stuff in place pretty well. With the tops trimmed off we didn't even need the adhesive stuff except on small pieces that didn't have a foundation tie to punch through.

Now I just have to decide in the next few days how to do the floor edges. Here are the options:
1. Leave the 2" of foam exposed and just pour the slab inside it. This provides the best insulation of the options, and would work fine for tile and floating or glued laminate or engineered floors, but doesn't leave a place to attach a tack strip or nail down a wood floor. This is also the easiest and cheapest option.
2. Cut the foam down at at least a 45 degree angle from the top of the wall to allow the slab to touch the wall at the top. This might be slightly better for attaching a tack strip, but doesn't fix the nailing problem for wood floors. This is the next easiest option, and still cheap.
3. Use a base plate 2" wider on the wall framing, hang it out over the top of the insulation, and pour the slab 1.5" higher, inside the base plate. We would still need a plate above the slab level for drywall and baseboards, so we would either have to block it all in or use a double plate. That means the cost of pressure-treated 2x8 around the entire foundation, plus an extra 1.5" of fill. It would be perfect for tack strips and nailing wood floors, but only around the outside of the floor. Hyrum said he normally uses the slab for some process I didn't understand when setting the base plate, but this would have to be in place before the slab, which would be harder. This sounds like the most expensive and most labor-intensive option.
4. Cut the foam down 3.5" all the way around and attached pressure-treated 2x4 along the top of the wall. This wouldn't require anything different for framing, but would require a tool to nail into concrete that I don't have and that Hyrum can't loan me until next weekend. This would be cheaper than 2x8, and wouldn't require any extra fill, so it seems better than option 3.

We also chalked a line around the inside of the foam 14" down from the top for the first layer of gravel, except in the elevator shaft where we need to be 24" down.

Hyrum came up and installed the temporary power pedestal. I didn't seem much of the process, but it seemed very quick. I'll call first thing Monday to schedule an inspection for it.

Jim also came to do the rest of the sub rough plumbing up to 14" below the foundation wall. He connected more 4" pipe to the sewer drain under the porch footings and ran it in 16' to the wall between the office closet and the pantry, then up above where the slab surface will be. Then he and Hyrum and I (mostly Jim and Hyrum) dug another trench under the porch for the water supply. We inserted a 1.5" sleeve that we will run the 1" copper pipe through immediatly before the fill comes, because we don't want it stolen. I emailed the building inspector to ask if the copper needs to be in place to inspect it, and if the sewer needs to be filled with water for testing.

We talked about whether to install a bucket for a future sump pump, and where to locate it and drain it to. We considered the floor of the elevator, but I would have to check with the engineers at the Elevator Company, and since that's also acting as the footing for the walls around the shaft, it might not work. We also didn't want to dig another trench under the porch to drain it. We decided it would probably be best to put it in the pantry, then run the drain out the back where the foundation wall is lowered for the dining room wall. It will need to be deep enough to reach below the elevator pit, since that would be the first place water would appear.

My next task will be to build a box around the elevator slab that will hold the gravel outside the pit back, act as the form for the pad, then act as a form for the outside of the wall around the pit that we'll pour at the same time as the floor slab.