What is a House?

It’s raining, and I’m waiting. Waiting on things to dry, to cure, or just to f***ing get here already. Either way, I’m waiting.

PAUSE ll

I mentioned in the last post that I needed to measure down 28” from the top of my finished basement floor (or “slab”), to find the bottom of my basement footing. If you know anything about residential construction, you were probably like, “why the hell is that 28”? Does this asshole have a 2’ thick slab?” No, relax. But also, get used to my house confusing you. Just trust that there are good reasons for its quirks. After all, I didn’t design it.

But let’s back up and get on the same page. What is a “slab”, anyway? Or a “footing”? What is a house?

A house is a dwelling. A shelter with a water and weather-proof envelope. It’s got modes of ingress and egress, sources of natural light, and usually running water. It’s usually got a heat and/or cooling source to condition the interior space, and often, places to prepare and cook food.

Thanks Captain Condescension, but that’s what a house does, not what it is.

Ok, fine. A house is a series of assemblies, designed to withstand various entropic forces (water infiltration and the associated fungal decay, wind loads, seismic activity, and frost heaving) and transfer the weight of those assemblies to the soil beneath in a way that is stable.

Let’s start from the ground up.

All houses have a “footing”. A footing distributes the weight of its load to the ground in such a way that it doesn’t just sink into the soil. This is generally achieved by having a wide surface made of a strong material (i.e. reinforced concrete). This lowers the lbs/sq ft of the load on the soil. For example: imagine pushing your finger into the soil an inch vs. pushing your palm into the soil an inch. You’d have to push WAY harder to get the same lbs/sq ft required to depress the soil with your palm. Different soils require different widths of footing depending on their soil bearing capacity, and the weight of the house.

On top of (and hopefully attached to) the footing is the foundation. The foundation transfers the load of the floors/walls/roof to the footing, as well as withstanding the lateral (sideways) pressure of the soil around it. In the case of a house with a basement, the foundation is probably the walls of said basement. In the case of a “slab-on-grade” home (i.e. no basement) it may be as simple as a thicker slab around the edges of the building footprint. Up here in the frozen North, where our winters are long but our spiders are small and mostly benign, our foundations are designed to keep that footing below the frost line. Here, our soil can freeze down to 4’ below grade. When it freezes, soil expands because soil is usually 25%-50% water. Anything on top of that soil in gonna move. As a rule, you don’t want a house to move. So, you want that footing to sit below the frost line. The foundation keeps the footing down low, while lifting the first floor up to the surface of the soil.

Now, you may be looking at that picture and thinking, “that footing does not sit 4’ below the soil surface”. Accurate, but it’s still below the frost line. How, you ask? Because we’ve raised the frost line. How, you ask? By insulating the soil underneath the footing. How, you ask? By using foam. How, y—— just…can I finish? Please?

We’re using a system called a “Frost-Protected Shallow Foundation” (FPSF). This mouthful of a strategy originated in Scandinavia (probably) and uses insulation around the footing and foundation to raise the temperatures of the soil beneath it. Soil is a heat sink; the warmer, deeper soil, a consistent 55ish degrees, will lose heat to the cooler soil closer to that cold, cold wind. Soil is also a furnace; the microbial activity within it produces heat, even in winter. Finally, a house (even a well-insulated one) will always lose heat through its floor and walls to the soil around it. By wrapping our soil in a foam blanket, we can keep it from freezing, even though it’s only 18” from that cold, cold, wind.

Isn’t that a lot of foam? Yes. Doesn’t foam have a huge environmental cost? Incredibly. Isn’t foam pretty expensive? Increasingly. So why not just drop the East wall footing down 3 more feet into the earth? Well, it’s complicated.

First off, concrete has its own costs, both financial and environmental.

Secondly, the FPSF allows us to keep the footing in the same plane all the way around the house. Which made forming and pouring it a much more beginner-friendly task.

Luther Inspection

Forming, pouring, screeding, floating and footing barrier (blue fabric) installation were infinitely easier for a newbie like me thanks to all the perimeter footings being in the same plane.

Ready for Crete

The 2” of foam under and around the footings provide a thermal break and create our FPSF. The Form-A-Drain system of perforated PVC gives both water and radon gas an exit pathway so they can’t destroy our house and lungs, respectively.

Pushing through at the end of a long day. That was a REAL tasty beer that night.

Also, the plan was always to wrap the footings in foam to create a “thermal break”. A thermal break prevents heat from flowing through a good thermal conductor like concrete, metal, or wood, (known as a “thermal bridge”) and out into that cold, cold wind. This will save us energy when heating our home. More energy than it took to produce, package and ship the foam here? Probably not, but we’re doing it anyway, Perfect and Good being enemies and all. Further North and we’d have to add significantly more foam in a horizontal sheet extending outwards to adequately insulate the soil. We’re in a sweet spot here; by simply wrapping the footing and foundation in 2-3” of foam, we get both a good thermal break and an FPSF.

Of the 67,000 tough choices we’ve made so far, this one I feel pretty solid on. Combined with Nudura Insulated Concrete Forms (ICFs) for the basement walls, and the REMOTE wall system for our above grade, wood framed walls, we’ll have a nice, cozy, lil’ house. I can live with the trade offs we’re making, especially when I think about those winter days where the sun is shining on the dark living room tiles and the masonry heater is giving off the warmth of the morning fire and the smell of baking bread.

Also, I’m tracking my hours for this build. Just the time I spend on the site. Doesn’t include any planning, coordinating subcontractors, ordering materials, nor does it include any of Danielle’s labor our any of our helper’s or subcontractor’s time. But you gotta start somewhere. 4 weeks in and here’s what we’ve got.

Through Week 4: Week of 9/5/2022

We broke ground on August 16th, but for the first 2 weeks I couldn’t do anything.

Hard to believe this was almost a month ago…Winter really is coming, and fast…

The first of many scoops!