Things are really zipping along on-site, thanks to some ingenious sequencing work by our Project Manager, Mike.
Here is the progress update in photos and a video.
Insulated Concrete Form (ICF) foundation walls are wrapped with self-adhered waterproofing membrane. 4″ of additional rigid foam insulation is being installed on the outside of the ICFs for a total of just over 6″ insulation on the exterior side:
Here we can see the exterior rigid insulation on the foundation walls and 6″ of rigid insulation topping off (and surrounding) the footings:
View from the back yard:
Below grade plumbing is installed; gravel is laid and protected with poly in preparation for pouring the below slab spray foam:
Spray foam was applied on Monday and Tuesday of last week (in four “lifts”, or separate applications):
We added 6.75″ total for R-40 below slab. The product is Heatlok Soya, which claims a more environmentally friendly blowing agent than previous generation products. It’s very sensitive to weather during application and curing, but the weather gods shined their temperate, dry smiles on us this week.
Spot checking the total thickness:
Here’s a short video of the application process:
Tubing was then installed for the in-slab hydronic radiant heating system. This was Thursday:
Tubing spacing is ~12″ in most areas; tighter in the baths, and generally more widely spaced than in a non-Passive House due to the low heating load.
And by Friday we had a poured slab – two slabs, in fact; one for each side:
We kept it watered between weekend rain showers to encourage an even cure:
I think this means we can no longer call our project “the hole”. If we aren’t careful, pretty soon we’ll be calling it a house.
Hi Christy: it’s been wonderful to see framing this week and the superstructures beginning to take shape!
I’d been confused over the past month by what looked at first like a regular concrete-walled basements being filled in with insulation and then topped with concrete! So the houses sit at grade on top of about a 4 ft. insulated foundation? I presume this means that basements sitting on a simple 6″ slab are losing a ton of energy earthward?
Thanks Rolf!
Foundation walls and footings are wrapped in insulation, and we actually use the rigid insulation as the forms into which the concrete is poured, so unlike wood forms, they don’t need to be removed afterward and they have the added benefit of stopping thermal bridging between the cold earth/cold air and warm interior. The slab on grade floor is poured on top of 6″ of spray foam. The spray foam is non-structural and its purpose is also to stop the transfer to heat between the warm interior and the cold ground.
And yes – most older homes, and even many new ones, are built with the floor slab poured on gravel/dirt with a sheet of poly between. So yes – lots of energy lost and cold feet! Nice in the summer, not as nice in the winter.