Tiny House Dimensions: What Size Can A Tiny House Be Without Breaking The Law?

tiny house dimensionsOne of the first questions I asked when building my own tiny house was how big should a tiny house be? There are several ways to answer this question, but it really comes down to whether you’re going to build your tiny house on a trailer or on the ground.

Most people want a tiny house they can tow down the road to travel or move if the need arises. So the focus here will be on tiny houses built on a trailer.

The Height Of A Tiny House: 13.5 Feet Tall

The Height Of A Tiny House

How high a tiny house can be is really governed by the height limitations of the Department of Transportation (DOT). More specifically, you want a tiny house that can fit under bridges and overheads while you drive down the road.

Most bridges on your major highways and on many side roads are built to have a clearance of at least 13.5 feet. That means you’ll want to consider building your tiny house just shy of that to be on the safe side.

My friend drove his tiny under a bridge where the sign stated it was 13.5 feet tall, but since it’s construction, had been repaved. My friend ended up pealing his ridge cap off his tiny house because of it.

The Width Of A Tiny House: 8.5 Feet Wide

The Width Of A Tiny House

The width of a tiny house is also dictated by the DOT if you’re on a trailer. In most states, you need your trailer to be less than 8.5 feet wide or you’ll need a special wide load permit. Understand that this measurement goes from the two widest points, which is usually your wheel wells. You should measure from the outside of the fender or tire to the opposite side of the fender or tire.

My suggestion is that you build your tiny house to be as wide as you can, but account for any roof overhang that might stick out. Build around the wheel well so that you have just enough insulation around it to maximize internal dimensions.

The Length Of A Tiny House: Up To 30 Feet Long

The Length Of A Tiny House

Here’s the really important thing to understand about tiny house dimensions. Because our height and width are constrained by the maximum size set by the DOT, if we want to increase our square footage, it means we have to extend the length of the trailer because we can’t build in any other direction.

Another element to this is your tow vehicle. In most cases, your maximum length will be 53 feet minus the length of your truck. Trucks suited to tow a large tiny house are typically 20-23 feet long, so your tiny house can be up to 30 feet long.

I should also note that the DOT primarily uses weight as its primary determining factor of upper limits. If your truck and tiny house on a trailer is over a gross vehicle weight (GVW) of 26,000 lbs, you’ll require special permits and a CDL driver.

Tiny House Square Footage

Tiny House Square Footage

Tiny Houses can range from 60 square feet up to 400 square feet when built on a trailer. Of course, you can build bigger if you build on a foundation. Typically your tiny house can be up to 8 feet wide inside, so your length will be the main variable that impacts square footage.

You’ll notice that a lot of tiny houses tend to be around 200 square feet — that’s because most people don’t want to have to tow a really big trailer. A 24-foot or 26-foot trailer is very cumbersome to tow, and since most people are pretty nervous about that size, going bigger isn’t very practical.

Also consider that the higher the square footage of a house, the larger the tow vehicle needs to be.

Here is a chart of the various trailer dimensions and their corresponding square footage sizes:

Trailer Length Trailer Width Square Footage
8 8 64 sq/ft
12 8 96 sq/ft
20 8 160 sq/ft
22 8 176 sq/ft
24 8 192 sq/ft
26 8 208 sq/ft
28 8 224 sq/ft
30 8 240 sq/ft
34* 8 272 sq/ft
36* 8 288 sq/ft
43* 8 344 sq/ft

*Gooseneck trailers only

When Do I Need a CDL To Tow My Tiny House?

When Do I Need a CDL To Tow My Tiny House

A Commercial Drivers Licenses (CDL) is required based on a few rules such as size or weight. While this is set by the federal government, it’s left up to individual states to set their own standards and oversee licensing.

Type of License Description Vehicles You May Drive
Class A CDL Required to operate any combination of vehicles with a gross combination weight rating (GVWR) of 26,001 or more pounds, provided the towed vehicle is heavier than 10,000 pounds. Tractor-trailers (also known as Semi, Big Rig or 18-wheeler), Truck and trailer combos, Tanker vehicles, Livestock carriers, Flatbeds. Most Class B and Class C vehicles, depending on endorsement requirements
Class B CDL Required to operate operate any single vehicle that isn’t hitched to a trailer (commercial trucks that have an attached cab and cargo area with a combined weight greater than 26,000 pounds, as well as trucks with a detached towed cargo vehicle that weighs less than 10,000 pounds). Straight trucks, Large buses (city buses, tourist buses, and school buses), Segmented buses, Box trucks (including delivery trucks and furniture trucks), Dump trucks with small trailers. Some Class C vehicles with the correct endorsements.
Class C CDL Required to operate a single vehicle with GVWR of less than 26,001 pounds or a vehicle towing another vehicle that weighs less than 10,000 pounds, or transports 16 or more passengers, including the driver. Double/Triple Trailers, Buses, Tank Trucks, HazMat Vehicles

Tiny House Trailer Dimensions

Tiny House Trailer Dimensions

An important part of this equation is understanding that the trailer you build your tiny house on is another limiting factor. If you can only build up to 13.5 feet tall, you actually have to subtract the height of the trailer to determine the interior useable space. Also account for wall and roof thickness in your calculations.

What this means is that for every inch of trailer height, you’ll have an inch less of space inside. The biggest determination of trailer height is your trailer style, of which there are three main types. Keep in mind the numbers below are averages and you’ll see some variations between manufacturers.

Utility Trailer Dimensions For A Tiny House

Utility Trailer Dimensions For A Tiny House

The most common trailer style to use is a utility style trailer. These are sometimes referred to as “bumper pull” or a “drop axle trailer.”

tiny house utility trailer

A typical utility trailer is around 13 inches from ground to bottom of trailer, 18 inches from ground to top of trailer deck, and 25 inches from ground to top of the wheel well.

tiny house utility trailer dimensions

Your common utility trailer will be exactly 8.5 feet wide from the outside of the wheel to the outside of the opposite wheel. Your wheels with wheel wells will typically be 15 inches wide, giving you an inside dimension of 72 inches between the wheel wells of your tiny house trailer.

tiny house utitlity trailer width dimensions

Popular Utility Trailer Sizes

Trailer Size Description
8 feet x 20 feet One of the most popular sizes because of its ease in transporting for tiny house dwellers who intend to spend a lot of time on the road.
8 feet x 24 feet This popular size allows more livable space while staying close enough to 20’ to still be comfortable to tow.
8 feet x 30 feet For those who have a family or prefer more room inside your tiny home, this length allows for more livable space while still being relatively easy to pull. Typically preferred for folks planning to live full-time in their homes.

Gooseneck Trailer Dimensions For A Tiny House

goosneck trailer dimensions

A gooseneck trailer uses a fifth wheel attachment point to tow with and is characterized by the hitch going up, over, then down again for towing. People like these because they’re a bit easier to tow and make tighter turns.

gooseneck trailer for tiny house

The other advantage to these is that you can build over the arm of the gooseneck, allowing you to have a longer tiny house. Normally you’d have to subtract the length of your tow vehicle from the maximum of 53 feet. Since the gooseneck actually goes over the truck bed, you regain some of that space.

The downside to goosenecks is their trailer decks are often thicker (but can hold more weight). Your typical gooseneck trailer will measure 17 inches from ground to bottom of trailer, 32 inches from ground to top of the trailer deck, and most often the wheel wells are flush with the deck height, so the top of the wheel well will also be 32 inches from the ground.

tiny house gooseneck trailer dimensions

Your common gooseneck will be exactly 8.5 feet wide from the outside of the wheel to the outside of the opposite wheel. Your wheels with wheel wells will typically be 15 inches wide, but built into or even under the trailer deck, giving you a full width of 8.5 feet since there are no wheels to block your building on it.

tiny house gooseneck trailer width dimensions

How Much Living Space Can You Have In A Gooseneck Trailer Tiny House?

Length of Bed: Trailer Size Length of Goose neck Total Length of Trailer Total Livable length
12′ 8 20′ 19′
14′ 8 22′ 21′
16′ 8 24′ 23′
18′ 8 26′ 25′
20′ 8 28′ 27′
22′ 8 30′ 29′
24′ 8 32′ 31′
26′ 8 34′ 33′
28′ 8 36′ 35′
30′ 8 38′ 37′
32′ 8 40′ 39′
34′ 8 42′ 41′
36′ 8 44′ 43′

Popular Gooseneck Trailer Sizes

Trailer Size Description
8.5 feet x 26 feet The most popular size, a 26-foot gooseneck allows for 33 feet of livable space since the extra length will ride above the vehicle pulling your home.
8.5 feet x 36 feet This is the maximum length for a gooseneck trailer. With the additional living space sitting above the hitch, a tiny house of this size will actually have 43 feet of livable space and 44 feet in total length.

Deck Over Trailer Dimensions For A Tiny House

Deck Over Trailer Dimensions For A Tiny House

While it is an option, a deck over trailer isn’t too popular because of how much vertical height you sacrifice, eating into your inside dimensions for living space. However, some people like this style of trailer because it makes for a simpler building process where you don’t have to worry about building around wheel wells.

tiny house deck over trailer

As mentioned, the downside to deck over trailers are that their trailer decks are much taller to go over the wheel well. Your typical deck over trailer will measure 24 inches from ground to bottom of trailer. It will measure 30 inches from ground to top of the trailer deck. Finally the wheel wells are under the deck, the wheel well right under the bottom of the trailer member, so the top of the wheel well will be 24 inches from ground.

tiny house deck over trailer dimensions

Your deck over trailer will be exactly 8.5 feet wide from the outside of the wheel to the outside of the opposite wheel. Your wheels with wheel wells will typically be 15 inches wide, but built in under the trailer deck, giving you a full width of 8.5 feet since there are no wheels to block your building on it.

deck over trailer width dimensions

Popular Deck Over Trailer Sizes

Trailer Size Description
8.5 feet x 20 feet One of the most popular sizes because of its ease in transporting for tiny house dwellers who intend to spend a lot of time on the road.
8.5 feet x 24 feet This popular size allows more livable space while staying close enough to 20’ to still be comfortable to tow.
8.5 feet x 30 feet For those who have a family or prefer more room inside your tiny home, this length allows for more livable space while still being relatively easy to pull. Typically preferred for folks planning to live full-time in their homes.

10-Foot-Wide Trailer Dimensions For A Tiny House

10-Foot-Wide Trailer Dimensions For A Tiny House

These trailers don’t differ too much from the above style trailer other than measuring 10 feet wide or more. If you decide go with a tiny house that is 10 feet wide, you’ll need to have a special oversized permit to transport it. You might also be required to have a CLD driver with flag escort vehicles depending on the state.

A typical trailer built to be 10 feet wide will be done in the style of a utility trailer. You’ll find that these trailers are typically around 13 inches from ground to bottom of trailer, 18 inches from ground to top of trailer deck, and 25 inches from ground to top of the wheel well.

10-Foot-Wide Trailer For A Tiny House

Your common utility trailer will be exactly 10 feet wide from the outside of the wheel to the outside of the opposite wheel. Your wheels with wheel wells will typically be 15 inches wide, giving you an inside dimension of 90 inches between the wheel wells of your tiny house trailer.

Tiny House 10-Foot-Wide Trailer Dimensions

Popular 10-Foot-Wide Trailer Sizes

Trailer Size Description
10 feet x 26 feet One of the most popular sizes because of its ease in transporting for tiny house dwellers who intend to spend a lot of time on the road.
10 feet x 30 feet For those who have a family or prefer more room inside your tiny home, this length allows for more livable space while still being relatively easy to pull. Typically preferred for folks planning to live full-time in their homes.

Tiny House Interior Dimensions

Tiny House Interior Dimensions

As mentioned, the biggest determination of your interior space will be from the deck height of your trailer, then of course your trailer length. Since you can only build up to 13.5 feet tall, you’ll have to subtract your trailer deck height and then also account for wall and roof thickness.

Tiny House Interior Width: 80 inches wide

Tiny House Interior Width

Because most wheel wells are a pretty standard size, you’ll have 72 inches between the wheel wells themselves. If you choose to build your walls above them, you can achieve a maximum of 80 inches wide from the inside of one wall, to the inside of the wall on the other side.

Tiny House Interior Length: Up To 29 feet long

Tiny House Interior Length

The length of your trailer will determine this dimension. A good rule of thumb is to take your trailer deck length and subtract 8 inches (4 inch thick walls times two).

Tiny House Interior Height: 10.5 feet tall

Tiny House Interior Height

Your inside height will be a function of your trailer deck height, minus your roof thickness, minus your subfloor, minus your flooring.

You can have a tiny house up to 13.5 feet tall. Often trailers are around 24 inches from ground to top of the deck, your sub floor is usually 4 inches thick, your flooring is up to an inch thick, and then your roof will be anywhere from 4-6 inches thick from inside finishes to the top ridge cap of your roofing.

I’d suggest also subtracting 2-4 inches as a safety margin.

Tiny House Loft Interior Dimensions: Up To 4 Feet 2 inches tall

Tiny House Loft Interior Dimensions

Don’t forget to check how your design will impact your tiny house loft height. Your main floor in your tiny house can be just barely taller that you are, giving you clearance for your head as you walk under your loft, but if your roof is too thick or you give yourself too much head room under the loft, you’re going to have a very small loft.

Let’s say, after accounting for roof thickness, trailer height, floor thickness, etc., you have 10.5 feet of inside vertical space. If you are 6 feet tall, your loft inside height will be about 50 inches tall. This is because you need to account for the loft floor supporting beams and decking.

tiny house loft

HOW TO SET UP A

TINY HOUSE

LOFT


Typically, your loft is built on 4x4s with a ½-inch piece of plywood on top. On top of that, you’re going to put your mattress, which can be anywhere from 4-12 inches thick. So crunch your numbers to make sure your loft height is going to work for you.

The final thing to consider is your roof style. If you have a standard hip roof, the peak will be directly in the middle of your bed, which is great if you’re a solo person and can sit up right in the middle. The sides of the hip roof will slope down on either side based on your roof slope, typically a 12:12 or 6:12 pitch.

You could also choose to have a shed style roof running from side to side or front to back. You could put the high end of your shed roof over the loft to maximize your headroom there.

Tiny House Dimensions For Canada

Tiny House Dimensions For Canada

In Canada, the size constraints are pretty much identical to those in the United States. While there are some variations between the provinces of Canada, because there is so much trucking between the two countries, they have pretty much matched each other.

Tiny House Dimensions For Australia In Meters / Metres

Tiny House Dimensions For Australia In Meters

I used to live in Alice Springs, so I’ve always been interested in tiny houses in Australia, particularly because housing costs are so insane there.

Centre-axled trailers (legally known as pig trailers) must not exceed 12.5 metres overall. The maximum distance from tow hitch to centre-line of the axle(s) must not exceed 8.5 metres. The rear overhang must not exceed the lesser of 3.7 metres, or the length of the load carrying area (or body) ahead of the rear overhang line.

Legal maximum towing weights in Australia, for tow vehicles under 4.5 tonne, the maximum laden trailer weight is the lesser of that allowed by the tow vehicle, tow hitch, or the maximum trailer mass. This overrides earlier legislation limiting towed weight to 1.5 times the tow vehicle’s unladen weight.

Determine The Right Size Tiny House For You

Determine The Right Size Tiny House For You

As you can see, there are a lot of variables that come into play determining the size of a tiny house, most of which stems from the trailer you choose. The main variable you can control to size your tiny house is modifying the length. A longer house will give you more square footage.

Your Turn!

  • What size trailer are you going to build on?
1 Comment
  1. So, if you are building off site, these are the maximum dimensions you can transport. But, if you are building on a foundation, what do zoning regulations say?

    Seattle allows up to 120 square feet for temporary housing for homeless people.

    I have yet to see the requirements for my area.

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