Planning the Foundation
The foundation you need depends a lot on what you are going to use your small house for.
Before you plan your foundation, you should plan your location. If you haven’t already, Flood-proof by Planning the Location >
Slabs are the normal thing in some areas. All of the wiring and plumbing runs through the walls or ceiling. Slabs are lower to the ground, so less steps. You have to have relatively level ground. If the ground is unstable, the slab may crack and you will have serious problems!
Our 2-car garage and workshop is on a slab.
Piers can be a great option for a small house that is built on site, but are not recommended for a modular house or cabin. They can easily be pushed over during delivery. Our Classic Manor New Day Cabin was installed on piers. We bought the model from Home Depot’s parking lot. They disassembled it and moved it here.
We pulled the permits and they sent two huge Russian men with picks and shovels to dig the holes. Once they got down deep enough, the inspector came out and checked and signed off. Then they put in rebar and poured cement. Called another inspection and it got signed off. Then, they brought our house in pieces on a flat bed. The floor was secured to the piers and it was anchored. I don’t remember how many inspections we had along the way, but it is still only an outbuilding. It was not possible to pull the permits for the model to be a residence.
An earlier project, that we were unable to get permits for, was going to be put on CMB-piers & runners, a sonotube foundation. Sonotubes are a glorified cardboard form to create a concrete pier.
If your zoning permits, you can put a small house on blocks, like a mobile home. The block is just used to level the building. Then it has to be anchored. The house could later be moved somewhere else.
A basement is the most expensive option to build, but if you are thinking about value and square footage, a smaller house on a basement is going to give you twice the square footage. You can finish it later. Where we live, as long as it is over 7’ high, a finished basement counts as part of the heated living space in the home. This allowed us to re-fi a house with a much higher appraisal. Some companies will put a small modular cottage or cabin over a full basement.
If you are just putting in a small house for storage, you can level it on blocks on gravel. You will never get a certificate of occupancy, though. You will probably never be able to pull permits and retrofit this to add to your considered square footage as anything other than an outbuilding.
Full Concrete Block Foundation with Crawl Space
Amish Made Cabins recommends a full concrete block foundation with crawl space.
This is a good idea, because you have access for repairs later.
Meadowbrook Cabin (our home, built from a log cabin kit) is also on a concrete block foundation with crawl space.
This is their requirement for the foundation:
- Concrete block foundation can be no more than 4 block high
- Concrete pads ground level down center
- Foundation should have anchor bolts – 2 at each corner and 1 every 6’
- Anchor bolts can stick up no more than 1 ½”, so the cabin can slide across the 2×6 treated plates
- Foundation should have pockets for the 4×6 beams so they can sit flush with the treated plates