HINT: It’s NOT this!
On a scale of 1 – 10: How critical do you think the cabin foundation is?
Let’s just come right out and be clear that the foundation is easily THE MOST important phase of your off grid build.
Today we’ll cover how we built the foundation as well as the reasons we went with this particular design.
If you’re new to The Off Grid Cabin then welcome aboard the adventure as we build our very or solar powered home off grid in Nova Scotia Canada.
We’re sharing every step of this one of a kind build with you as well as a host of other off grid goodies!
Enjoy the adventure and hey… if you found it fun, informative, or entertaining be sure to help us out by sharing this post with your social media peeps or this Pinterest Pin!
There are several different foundation designs we’ve seen used for off grid homes.
They range from simple footing and pier designs like ours al the way to fully poured concrete basements or crawl spaces.
Here is a look at several different foundation designs ranging from simple to complex.
1. Cement Pad with Cinder Block Footing and Beam
2. Poured Concrete Footing with Pier and Beam
3. Cement Sonotube with Pier and Beam
4. Poured Concrete Raft
5. Poured Strip Above Ground
6. Poured Strip Below Ground
7. Poured Basement and/or Crawl Space
There are pros and cons to each of the foundation designs.
However, it came down to four factors that determined our choice.
- Overall cost of the build ($20K)
- Limited time to build the cabin (we had 15 days total)
- Ease of build for just two people
- Limited access to the remote build site (we had an excavator for one day)
Our foundation design is both incredibly economical and effective at creating a rock solid building platform.
It is especially easy to build in an off grid location and with a limited crew. Mostly it was just my Dad and I.
Heavy machinery is expensive to bring in and the soil type may not always conducive to you building a fully dug out basement.
A poured foundation, or even a cement pad, can cost thousands and take weeks to build.
Again, a cement truck may not even be able to access your build site. They certainly couldn’t on ours.
Our foundation was simple to design and quick to build.
TIP: Our floor design (1″ rigid foam core sandwiched between 3/4″ PT plywood) provides an excellent thermal break from the cold harsh winters of Nova Scotia and creates a strong and rigid building platform.
When built properly, your foundation will easily last the lifetime of the cabin and most importantly, will allow you to keep your off grid home level and rock solid always.
Previously we began to lay out the footings to prepare for what lay ahead today.
Be sure to check out our #1 Secret For The Perfect Foundation
Today we finish installing those footings, build the main support beams, and begin to frame the floor joist.
All this will finally give us a good idea of just how cozy our off grid home is going to be.
We leveled 12 spots on undisturbed soil using 2 bags each of crusher dust where the 24″ X 24″ cement pads will be placed.
On top of those cement pads we’ll place 8″ cinder blocks side by side and place the main support beams on top of a piece of pressure treated spacer.
TIP: Never directly contact wood that is not pressure treated with the concrete or cement blocks/pads. The moisture from the concrete can be drawn up into the wood, and after a period of time the wood will rot. You can maintain separation using PT spacers like we did or use an appropriate gasket made from soft plastic or foam.
Initially we used 4 cinder blocks on each pad (2 on top of 2) but we found that was a little too high to our liking.
Leveling the ground with sand (crusher dust)
Getting the ground perfectly level is critical in ensuring the remainder of the structure is level, won’t shift, and allows for every beam, board and joist to line up perfectly.
My Wife helping level out the ground.
The whole family worked together to build our cabin.
Below: Laying out some lumber scabs to ensure the pads are all the same height.
Below: Here’s a panoramic view of our build site.
We used 16ft long 2×8’s quadruped up to make up the three main beams that will support the floor joist.
To fashion the beams we over lapped the 2×8’s making sure to use construction adhesive and nails the full length of the beam. When we had two layers built we simply overlapped another row of 2×8’s and repeated the process until we had four layers.
TIP: We used DAP Subfloor Construction Adhesive whenever we needed to build our beams or put down subfloor. One can of this expanding foam is equal to 8 tubes of regular construction adhesive!
Below: These are the 9 footings that will support the three main support beams.
Each of the three main support beams are free floating on their respective cement block without anchoring them down.
This allows for the footing to shift (with the change in seasonal temps) “if” that happens at all. If the beam was anchored to the footing, and one footing was to shift, the cabin could experience a shearing force and may cause a weak point in the footing and/or structure.
By allowing the beam to ride on-top of the cement footing the entire building can slide on the foundation to prevent unwanted forced from occurring.
Now to be 100% clear when I say “shift” or “slide” I’m talking millimeters here. Please do not misread that and think your home will be sliding around like skates on ice! Our cabin foundation hasn’t moved whatsoever over the past three years. That’s going from +30 in the summer to -30 in the winter and being built on our gravel/soil foundation.
A Superior Tool for Speed and Efficiency
Without a doubt THE BEST single purchase we had before tackling this build was this Dewalt Cordless Framing Nailer.
You’ll hear me go on and on about this one tool throughout the build but I honestly cannot give it enough praise.
You may wonder why we would spend the money on something like this when we could have just used a goodl old hammer and nails?
It was a massive time saver, shaving days off the overall build, and allowed us to nail in places we just would not have been able to swing a hammer.
3 more pads will be placed between the floor joist and the tent in order to support the 3 – 6″x6″ PT Posts for the front deck.
You can see we reduced the height by one cinder block on each pad and separated the beams from the cement with a few pieces of pressure treated wood.
Bellow: These are the footings we will use for the three 3 – 6″x6″ PT Posts that will support the front deck.
We used 2×6’s 16″ on center for the floor joist and we will top the floor with 3/4″ tongue and groove OSB.
On top of that we will put down 1″ think ridgid Pink Styrofoam to act as a thermal break and then top that with more 1/2″ OSB.
Completed the basic framing for the floor joist.
The pressure treated beams give a sneak peek at the size of that patio.
The front deck will be 20′ x 8′ and use 3 – 6″ x 6″ posts used to support the front edge of the deck roof.
Today we finished up the footings, the three main support beams, and began to frame the floor joist.
Finally we get a good idea of the floor space we’ll have and how cozy our 20′ x 24′ cabin might feel like.
In our opinion, this is by far the best method for building a small cabin foundation with our soil type, climate and location.
While each off grid build situation is different remember there are several general considerations when building the foundation for your home.
- Ground type (gravel, soil, rocky, slab, tree roots)
- Ease of clearing the land
- Overall footprint
Next time we finish up the floor joist, put in the 3 – 6″x6″ pressure treated front deck posts, and ensure the entire foundation is level and square before we put down the first layer of OSB.
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Are you ready to tackle your own off grid foundation?
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