Foundation Slab

It was an exciting time at the site on Thursday! Starting at 8:30am, I got to see four large cement trucks navigate the narrow streets into my driveway to pour out the slab for the foundation.

The pour begins:

There's no turning back now! We can't even drill into the concrete after it has set because it would risk puncturing the embedded piping. Also of note in that picture is the 40ft coil of copper wire (lower right) leading to a Ufer ground setup in the foundation. That'll hook into the electrical box of the house. Here you can see the contractor directing concrete from the tube in the sky:

At the recommendation of the architect, we had "Seattle Sidewalk" pigment added to the mix to darken the slab. He said that concrete color matching is an inexact science, and he's had good results with that color in the past. It looks good in the photos!

Once the last concrete truck drove away, the troweling process began:

I was told they were out there until around 6pm. I can't wait to see what it looks like after it has cured! Next up are the retaining walls for the foundation.

Foam, Rebar, and PEX

After the gravel, the next step was to lay down a vapor barrier and cover the entire footprint of the foundation in a 2" thick layer of foam panels. 

Next step - take rebar...

...and tie it up in a grid.

Those red tubes you see there is PEX for the hydronic heating system. It's tied to the rebar.

All the pipes feed into the mechanical room of the house:

After this work gets approved by the city, it can be buried in 8" of concrete. This will hopefully happen later in the week!

Grading and Gravel

With the side sewer line installed and buried, it's time to focus on the foundation of the house. There's quite a bit that goes into creating it. The first step was to flatten and compact the ground. Next, the plumber installed the sewer pipes that lead to all the drains in the house.

After that, they brought in and compacted a 12" layer of gravel across the entire surface. This is to add stability and proper drainage to the ground.

While I was on site, I saw them prepare for the next step:

They're unloading 2" rigid foam panels. Those will be laid across the entire surface of the gravel in order to insulate the foundation from the ground. This will prevent heat from escaping the house through the foundation and will make the bottom floor seem more like a normal room, unlike a typical cold basement.

That truck also has a bunch of rebar. This will be installed above the foam layer to help strengthen the 8" thick concrete slab.