Picking a Type of Foundation
A brief summary of things to consider when picking a type of foundation for your cabin.
The start to building any kind of structure is building the foundation. The type of foundation you pick will depend on a number factors including the type of ground, slope of the ground, environmental conditions (water and temperature), building codes, and budget. Here is a brief review of these factors and how it pertains to our cabin build (take with a grain of salt as we are by no means professionals).
Type of the Ground
When we say type of ground we are referring to what the ground is made of, for instance sand, rock, peat, topsoil, shale. But I am also referring to the characteristics of your ground, does it retain moisture or not, is it generally hard or soft?
Our ground is made mostly of large rock and shale. The ground is very hard and compacted, making it near impossible to dig or excavate even with heavy equipment. Directly behind the cabin footprint is a large rock, and bedrock is present less than a foot underneath the ground where the cabin will go. Our ground does not retain moisture, meaning after rainfall the water does not stay on top of the ground but percolates and runs off the surface.
Slope of the Ground
We used an excavator to level the ground by eye. Although the land looks level the front of the land is actually several feet lower than the back of the land. We are building a 26’ x 46’ foundation so there will be a significant amount of work to bring the foundation to the level. Certain types of foundations, such a concrete pad or footing requires either more leveling or more concrete work, making it a more expensive option for large cabins on uneven land.
The climate can be a big factor in picking building methods and materials for many parts of a structure build. Freezing and fluctuating temperatures, like we have here in Canada, are a consideration. During freezing and melting, the water in the ground will expand and contract causing the ground, and whatever is on it, to move. Well drained soil, and building below the frost line can help prevent movement of the foundation in these conditions.
Moisture in the form of water and snow is the other major environmental factor. Wood that is exposed to moisture is at risk of rotting, if there is significant rain or snowfall in your region you should ensure that wood in the foundation is not exposed to moisture. In our case wood is kept off the ground with concrete pads, lumber used near ground level is pressure treated.
Since we are building a cabin not located within a town we do not have any by-laws to follow. Our land is remote and does not have electricity, water, or government roads so the federal building codes will act as our guide. We consult building codes to ensure we have sufficient support.
You should always to check that your plan complies to local codes, as this may affect the type of foundation and materials you are legally allowed to use.
All the other factors may help you determine which type of foundation may work the best, but ultimately the best foundation is the one you can actually build. If money wasn’t a consideration for us we would of probably picked a Styrofoam form concrete foundation, insulated and solid. But we are trying to build the entire cabin for less than $15,000…. So not really an option.
After weeks of research and talking to friends and family we decided a pier and beam style foundation would work. Because we have solid ground the piers shouldn’t move too much and we will be able to have a level foundation for a fraction of the cost.
Initially the plan was to use telephone poles or 8x8” lumber, driven vertically into the ground to the bedrock, and supported with cross members for stability. We soon realized the land was too solid to dig down, so we changed the plan to cement pads to rest our piers on.
Then it was suggested by friends and family (who've built their own cabins), that instead of poles or lumber extending vertically from our cement we should stack cinder blocks or pressure treated lumber horizontally on the cement pads for stability. The cost would be greater (picture a Jenga tower of lumber vs a vertical pole), but it would be more stable and also easier to adjust the height. The picture below shows the foundation style we settled on.
We luckily found a great deal on used cinder block from a local farmer. Recycled materials at less then half the cost, that is our favorite! We purchased all they were selling, enough cinder blocks to complete about half of the foundation. In addition to cinder blocks we used new pressure treated lumber, and a recycled gift. My dad had replaced his cabin's foundation a couple years earlier and he had kept several wide treated logs/railway ties, thanks dad!
Now that we had cleared our land and planned our foundation we could finally get started with the good stuff!
Subscribe to follow along with our cabin build, and start reading about how we built our foundation here.