The Walden Effect: Farming, simple living, permaculture, and invention.

Planning a concrete foundation for a new room

Slab on grade

As you can tell from Mark's post, we've decided to put the floor of our wood-stove alcove at ground level so we can use concrete. This is a new building endeavor for us since lugging concrete back to our old core homestead just wasn't happening! So I spent a while researching to figure out the nuts and bolts.

Words are so important in projects like this, and here are the relevant ones for this project --- we're building a frost-protected shallow foundation (a subset of slab on grade aka monolithic slab). Basically, by insulating the outside perimeter, this type of concrete foundation dramatically reduces the depth and complexity of the required footer.

Frost-protected shallow foundationIn our case, we only need to go down 12 inches and to use insulation with an R value of 4.5 around the perimeter (which equates to 1 inch of Type IV expanded polystyrene). If you live further north, you might need to add horizontal insulation sunk into the ground outside the perimeter of the foundation as well. This document walks you through all of the calculations.

There's lots more to plot out. But this should carry us through the digging stage!

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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I know in our area, we would have to have permits and inspections to build something like that. Heck we had to have permits to have the foundation waterproofed. (we have a neighbor who hired a reputable company that failed to get permits and their project has been shut down at the exposed foundation state for 2 months now). Whats it like in your neck of the woods?
Comment by Rebecca Thu Oct 11 09:57:29 2018
Rebecca --- We asked about that last year at the courthouse when we went to register our trailer. They told us that we didn't need any permits for an addition, but that they will cruise by from time to time and assess the new square footage and add that onto our property-tax bill. So it sounds like we're good...until tax time.
Comment by anna Thu Oct 11 15:24:37 2018
I'm sure you are aware but be sure to put a vapor barrier under your slab.
Comment by Brian Fri Oct 12 16:31:08 2018

How about permits on the installation of the wood stove and pipe? What sort of inspection for the home owners insurance? I know on your last place, you said you did not carry insurance (as an old trailer in a place the fire department could not access was pretty much something no insurance company would touch)

I have known others that were told that you simply can not put a solid fuel stove in a manufactured home and be covered by home owners insurance.

Comment by Eric Sat Oct 13 09:04:00 2018

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