Building A Tiny House On A Foundation – What You Need To Know Before You Build

When I built my own tiny home, I hadn’t really considered building a tiny house on a foundation. But in recent years, more and more people are skipping the trailer and directly building a tiny home on a foundation.

I get many questions about what it costs to build a tiny home on a foundation, what the legal struggles are around building codes, and why you might or might not want to consider this option.

Can You Build A Tiny House On A Foundation?

Absolutely! You can build a tiny house on a trailer or a traditional foundation. You could even have a basement foundation for your tiny house if you plan to build on permanent land.

When you start building your future tiny house, you’ll need some type of supporting permanent foundation to rest the house on and build off of, unless you’re building on a trailer for mobility. There are several types of tiny house foundations that you can consider for your build. Each type has pros and cons, but all will be able to support your tiny home.

Tiny House Slab Foundation

A slab foundation can be one of the easiest tiny home foundation options and learning how to build a tiny house foundation from concrete is simple for beginners. A concrete slab foundation is a simple pad made by first creating a wood frame called a form. Then you fill the form frame with concrete to form a slab. In some instances, you’ll lay in rebar or wire mesh to reinforce the pad, but that isn’t always necessary. Typically, a 4-6-inch-thick slab is all you’ll need to start building your tiny house; make sure you preplan any drain lines. In low-lying southern states, concrete slab foundations are pretty standard in the construction process.

Tiny House Vented Crawlspace Foundation

Wondering how to build a crawlspace foundation? A vented crawlspace is formed by short walls that you build your house on. Typically, footers are poured around the edge of your foundation, and walls are built on those about 2-3 feet tall. A vented crawlspace foundation works great because you can run all your wires and plumbing in the space. If there is ever an issue, you can crawl under your home to get access to fix them. Your crawlspace walls will have some vents in them to allow for moisture out. The downside is that tiny house crawlspaces (or any crawlspace for that matter) are typically dark, dirty, and can lead to moisture issues.

Tiny House Sealed Crawlspaces

A sealed crawlspace is basically a mini basement as the foundation for your tiny house. The sealed space differs from a vented crawlspace because instead of being open to the outside environment via vents, you seal it off and condition the space as part of your building envelope. The sealed crawlspace is my preferred tiny house foundation method because we cut down on potential moisture issues, keep bugs out (mostly), and can use the space for storage! Typically, these will be built using the same walls surrounding the outside, but then a floor is poured in after. Make sure your contractor insulates and installs a vapor barrier!

Tiny House Basement Foundation

This is one of the most expensive tiny home foundation options, as you’ll be building down into the earth, which requires engineering. The additional square footage gained for extra storage space or additional living space is usually very affordable but brings with it more hoops to jump through. Make sure you check with local building codes about egress and ensure you have a contractor that properly drains, seals, and insulates the basement. Basement finishing is critical to avoid flooding in bad weather and provide that excellent storage tiny house owners always need.

Skids Or Runners For A Tiny House Foundation

Skids or runners are another tiny house foundation option that serves as a semi-permanent foundation but is also somewhat mobile. These are simply large timbers placed on the bottom of the house that act as runners to drag the house on. The tiny house skids are usually made of lumber, or sometimes steel, which gives you the best of both worlds.

Tiny House Piers or Tubes Foundations

The last type of tiny house foundation is a footing placed in a grid pattern into the ground with a bracket on top; this bracket connects to the underframe of your house. These piers are rows of poles laid out in a grid with large timbers running between them to form the sub-floor framing of your home. They’re ideal for sloped lots where tiny house placement options are a challenge and can be an excellent choice for DIYers.

Cost To Build A Tiny House On A Foundation

One of the significant expenses associated with a tiny house on wheels is the trailer, costing between $3,000 and $6,000 for the trailer alone. A simple slab might only cost you $1,000-$2,000, including labor. So right off the bat, you’ll be saving a pretty good chunk of change by skipping the trailer and opting for a tiny house foundation.

That said, you’ll have to make sure you’re complying with all applicable zoning ordinance regulations, which can incur additional expenses. With a permanent foundation, if things go poorly with the city, you can’t just pick up and leave. Building permits for your house project will vary based on your location, but nationally you’re looking at an average of $1,200 for all your permits to build your house. Add to this that they’ll most likely require you to have a water line and sewer connection, which is always expensive. My city charges a whopping $11,582!

If you live outside city limits in a rural location where you can’t get traditional utility hookups, you’ll need to drill a well and install a septic system. Read more here about how I installed septic on my land.

Many people, myself included, choose off-grid options like a compost toilet and solar panels because they’re more affordable in the long run. The most significant financial benefit of off-grid options is that you don’t have any bills to pay after the initial cost. Being pushed to more affordable options meant I had to step outside building codes and thus become an illegal dwelling, which then led me to choose a trailer with wheels, so I could move if I needed to.

You can see that while you’ll save some money on the trailer, you’ll have to spend a lot more to comply with building codes and local regulations. After that, building the house will be about the same for the rest of the details. Compared to building an average-sized new construction home, the average cost of a tiny house on wheels or any type of foundation is still far more affordable.

Pros and Cons of Building A Tiny House On A Foundation

There is a lot to consider when it comes to building a tiny house on a trailer versus building on a foundation. Tiny homes have been traditionally built on trailers, but that doesn’t mean they have to be. Here are some of the pros and cons of building a tiny house on a foundation:

How Do You Build A Tiny House On A Foundation?

The primary connection between the house walls and the foundation is built on a pressure-treated sill plate, which is just a 2×4 or 2×6 laid on its broadside. Between the top of the foundation and sill plate, you want to use a gasket to act as a capillary break between the concrete and the wood, seal the joint for air and prevent bugs from getting in. I usually recommend using a foam gasket with some contiguous beads of acoustical caulking because it will make sure that the connection is always sealed tightly.

You’re going to need to anchor the sill plate to the foundation itself with anchor bolts. Sometimes these are laid when pouring; other times, people drill holes and add them after. Your local code enforcement will have specific requirements on the type, spacing, fasteners, and more, so check with them first.

Once you have your sill plate installed, sealed, and anchored, you then use that as your bottom plate of your wall framing. Consider how you’re going to run your floor joists when you pour your foundation. A good contractor will help you work out all the details on this front. Below is an excellent diagram of this process. If you like these details, my book, “How To Build A Tiny House,” is loaded with 160 custom diagrams with details like this.

Tiny House On A Foundation Design Ideas & Photos

Here are some great tiny houses built on foundations to help you get some inspiration for your own home. Keep in mind that your local municipality will have specifics on building codes concerning details, building methods, and sizes you’ll need to comply with.

Orcas Island Cabin

This is a dream cabin of only 400 square feet built by Vandervort Architects that I’d love to stay in myself. A simple house with rich woods on an island in the Pacific Northwest.

Escape Cabin

This one is a personal favorite because of the large screened porch and the smart bedroom layout. This small house on a foundation is around 400 square feet and is built on a steel frame, so it can be transported in a pinch. Check out this house and others from Escape.

Muji Hut

I have personally thought about building one of these on my land — the simple design is super minimalistic while still having a lot of functionality. A simple room with a bed and a heater is all you need for a weekend getaway. I figured I could have some hidden storage in one of the walls and a simple outdoor shower off the back.

The Rocker

Viva Collective designed this with an innovative L-shape that allowed for a great deck to be added. This shows that you don’t need to be confined by a trailer, and the results can be stunning!

Shipping Container Trio House

This is an interesting shipping container home that is made up of three different containers. Shipping container homes are growing in popularity as an affordable home option. They can be had for a few thousand dollars and provide most of the structure of the home.

Should You build A Tiny House On A Foundation?

In the end, I think you need to decide if you’re willing to jump through all the hoops and deal with the red tape of building your tiny house on a foundation. Having a legal house is peace of mind, but that comes at the cost of extra permits and requirements.

Many people opt for a trailer because it skirts most of those issues and expenses, but a tiny house on a foundation is an excellent option for those who want a tiny house outside the normal trailer footprint.

Your Turn!

• Trailer or foundation, which do you choose?
• Which of these tiny home foundation options sounds most appealing to you?

By Ryan Mitchell on July 6, 2021   /   Tiny House   /   17 Comments

Tags: Construction, Design, Tiny Home