Road Limits for Tiny Houses on Trailers

Building a tiny house on a trailer is one way to avoid certain limitations that are often unavoidable when building on permanent foundations. For example, while building codes can be a great guide for building a safe home, I’ve never heard of a planning department expressing any desire to examine a tiny house on a trailer.

It makes sense actually – tiny houses on trailers can move to and from different communities; who would inspect them? The truth is tiny houses exist in a grey area between traditional houses and travel trailers.

Size

But this scale of home is not entirely without limits. If you want to be able to pull your house down a highway without a special permit, it must conform to certain size limits. In most U.S. states this maximum size is 13.5-feet tall, 8.5-feet wide, and 40-feet long – 65-feet maximum including the tow vehicle. Extra care must be taken to squeeze the house into this semi-trailer sized imaginary space.

Below is a simple drawing that shows how quickly everything adds up. You can instantly see why so many tiny houses have roof pitches that are no steeper and 12/12 (45-degrees) and walls that are a bit shorter than 8-feet. At first the design challenge seems daunting, but as you browse through all the different homes people have built, you can see that there is still quite a bit you can do within the box.

Weight

Commercial travel trailers are designed to be lightweight and aerodynamic. Tiny houses are typically built from heavy building materials, like normal houses. This can make it much more comfortable to live in year-round but every foot in length adds-up and increases the requirements for the trailer and tow vehicle.

For example, a Tumbleweed Fencl is about 19-feet long and weighs just shy of 6,000 pounds empty. Add your belongings and you might start pushing 8,000 pounds. Now theoretically double the length to the 40-foot road limit – you could be talking about a house that weighs 16,000+ pounds, which would require a really big pickup to tow. This is not unthinkable of course, they build pickup trucks that can pull trailers that size; but it is an important consideration to make before committing to that scale.

Freedom

Building tiny houses on trailers can provide a lot of flexibility and freedom; but like every design challenge, it doesn’t come without trade-offs. While you may not have to talk with building inspectors, you are pretty much on your own to build a safe and strong home on your own.

It’s best to use building codes as guides and add extra reinforcement like earthquake and hurricane straps – after all the house will encounter 60 MPH winds and road vibrations. For some this may sound adversely challenging – to others it sounds like music to their ears. In either case try starting your design process from these practical size and weight limits.

If you decide to build a tiny house I’d love to share your story here on Tiny House Design. I also strongly encourage you to get a free blog at WordPress.com or Blogger.com and journal about your experience. We’re stronger together.

71 thoughts on “Road Limits for Tiny Houses on Trailers

  1. Steve W. says:

    Mike, you must have been reading my mind! Thanks so much for the article and diagram. I was wondering how high off the ground typical trailer flatbeds are — certainly don’t want to tow something higher than the 13.5 foot limit and wind up with a partially missing house!

    I’m also really looking forward to that upcoming “ultralite” design you’ve been tinkering with. Perhaps that would allow for a lighter and less expensive trailer then?

    I’m hoping to finally get started on my own “tiny house” project by sometime next year. My goal is to be able to cook, do laundry, have enough storage for my stuff, and have a friend or two over for lunch, all in around 100 square feet — difficult I know, but not impossible! I’ll keep you posted — and thank you so much for being such an inspiration to us, your readers! You’re one person who’s really got me excited about going forth with my project!

    • Keith Wolfe says:

      We stopped at 32 feet, not because we had they limits in mind, We were just thinking of the swing as we would travel with her. While she sits mostly all the time, the two trips we have made with her fishing was a real blessing for my son and I. We use the loft for him and the first floor bedroom for myself (handicapped). The point of the whole was to replace a cabin that has been in our family for generations (it was just beyond repair after 120 years). You will run into somethings you did not think about!

    • james m murphy says:

      Thanks for the info, i wont go higher than 13.5. and no wider then 8.5. I am getting ready to build a caboose as long as i have some room uptairs ill be good, Can you give me any pointers on building the most ridid structure possible. i will be living in it in the long run. I’m also looking for floor plan designs, I need a full bath, full kitchen and a nice big comfy bed lol. any input will be great thank you. Hopefully i’ll get the shell done before winter, I have to strip the 26 foot camper down to the frame so it will at least be work in progress.

      • David -Paul says:

        Just a note regarding rigidity google Pythagorean triples the standard vertical stud wall type framework is not rigid.

  2. Sarah L says:

    One thing that I found out when doing some research is that New York state restricts how many pounds you can haul to 10,000 if you just have an average drivers license. Not sure what it is for other states, but it is something to consider if you do not want to pay for an upgrade to your drivers license.

  3. alice says:

    It’s amazing how much you can fit in a space if you design the storage from scratch according to exactly what you need. Once you decide what’s staying the next part is figuring out how to keep it stored but easily accessible. The less you have to move to get at other things the better – keep things containerized so you only have to move 1 piece to get behind it instead of several loose items. You can design cupboards around your storage containers rather than trying to find something later that might waste several of those critical inches. It’s amazing where you can fit a narrow pullout/foldout cupboard that lets you see all its contents without rummaging. A lot of the frustration in small space living is due to poor storage access.

  4. Gretchen Elsner says:

    My boyfriend and I are building and designing a 34′ travel trailer we hope to power by solar. we are used light gauge steel framing to build the walls. the whole structure, after sided etc, will only weight about 3,000. steel offers great strength to weight ratio, and also cuts down on flammables in a vehicle that will contain propane use and also the batteries for the solar system.

    • Scott says:

      I am considering building a trailer abut the same size you are with steel framing. How is your build going?

    • Sean says:

      I know this is 5 years too late, but I was wondering how everything turned out with your 34′ travel trailer. My wife and I would really like to build our tiny house on a 32′ trailer. My only real concern is taking it onto the highway to its semi-permanent location. If I need to, I can have my father drive it since he has a CDL, but I was just wondering if it was very difficult to take on the interstate and how much yours ended up weighing. Thanks!

    • Marissa says:

      my boyfriend and i were also wanting to build a tiny home on wheels. we have a layout but we know we are going to have to really get down to inches and feet and might have to sacrifice some of the design features. how was the build?

      • Allen says:

        Has anyone considered building one out or in a used school bus? You can pick up a good running old school bus really cheap and they can take a good load and I have seen some really good builds set up already out of some. I’ve been thinking of utilizing one myself, and was just wondering if anyone on here has done one yet and if so how well it worked for you? I know that the ones that I have saw the pictures of was really nice and from what pictures I saw listed and read, they wasn’t that hard to convert and they don’t require towing around as they already have a good power plant, engine ready to do the task at hand. Any thoughts on this subject? Thanks, Allen

  5. Steve says:

    I am looking for more info on width allowances for permitted moves. As I see it, the major advantage of building on a trailer is to avoid the building inspectors and not that I want to move all around the country that often! If I wanted to move that often I would just buy a recreation trailer. So, maybe I can build wider than 8’6″ and just get a permit with a wide load escort. How much wider? I am talking about something like how they trailer manufactured home halves, not a full road closure move.

    • Eric Lipinski says:

      Stop at any truck stop and for about 8 bucks you can buy a Rand McNally road atlas. This is a guide for truck drivers.It will have all the laws broken down by state that would affect your heights, and weights. It will tell you where all low clearances and bridges with weight limits and axle limits. It also has the number in each state you need to call for wide loads getting permits and escort vehicles. It even has a map of all the states and some larger cities. Hard to believe you can get all that for just 8 bucks, save a lot of time asking questions to people who don’t know much more than you.

      • Bill says:

        We spent 4 years living, and on/off traveling, in a 37 foot fifth wheel. We are seriously considering turning our trailer into a tiny house. We have found that most RV s are not made for fulltime living. The biggest issue is condensation. We now have roof damage as well as mold. This in a 2006 model that was only used 3 weeks wen we purchased it. One thing we found with under passes and bridges, is that the posted max height may not be accurate due to the resurfacing of the road.

    • Joel says:

      I too have been thinking the same thing Steve. In fact I am in the process of designing a tiny house that will exceed the height and width maximums used by most tiny houses.

  6. Steve says:

    FYI, just looked up regulations in Washington state – $10 special permit fee you
    can get a permit to move a “park trailer” which exceeds the standard width(8’6″) limit. A good place to start, if interested, is RCW 46.44.092 – Special permits — Overall width limits, exceptions — Application for permit.(14ft & 16ft daylight hrs max)
    http://apps.leg.wa.gov/RCW/default.aspx?cite=46.44.092
    And FYI, the height limit is 14 feet in Washington State.

    • Doug says:

      Typically there is no special limit based on length unless your total vehicle length (including tow vehicle) is over 60 ft. The biggest requirement is the length and height. However to drive with a standard drivers license there are weight limits and those can vary depending on the state/ province, so be sure to look into it before building

    • Eric Lipinski says:

      Its not the length of the trailer that will require the cdl, its the weight. 26,000 lbs is the most you can weigh, 1 more pound will require a cdl. This is any combination, and the towing vehicle has to be under 10,000. So if you using a truck the is 7000 lbs, you would be able to haul a 19,000 lb trailer. Keep in mind adding fuel to a tank, or more people in a vehicle, will add weight so leave yourself some wiggle room. Trucks have been shut down because they fueled after weighing and hit a scale not thinking about the extra weight. Also brakes, air brakes require an endorsement, this is why a 26′ box truck can be non cdl but a 16′ could require a cdl. This article says 40′ is the max length of a house trailer. It says a tumbleweed that’s 19′ is about 6000 and with belongings about 8000, so figure how much its weighing per foot, 8000/19=422×3=1264, so another 3 feet should bring you to about 9264 lbs… But yours will be different for sure but leaves plenty of room so you should have no problem staying legal.

      • Stephanie Spears says:

        Thanks Eric! Definitely check the weight after loaded with all supplies, furniture, etc, and all fuel and water tanks full. My husband and I were truck drivers and are now considering building a tiny house on wheels (which to us will be like double the space we were accustomed to in the truck, lol). I don’t just want to buy an RV because I want to do it myself. When we were driving, we have been ticketed before for overweight when all we did was fuel after we left the shipper. It’s something that a lot of people don’t even consider. Fortunately, he retained his CDL so we can be a little overweight and still be OK. But as the tiny house movement continues to take off, those who want to restrict them will definitely try to use this as an excuse to pull someone over.

  7. DAVE DUCKETT says:

    CONTRACTORS USE A 1/8 SHEET OF PLASTIC THAT IS VERY STRONG COME IN 4 X 8 SHEETS AND WEIGHTS JUST OUNCES AND VERY STRONG COULD BE USED ON STEEL STUDS BOTH SIDES WITH HARDLY ADDING WEIGHT GARDENER ALSO USE THIS FOR GREEN HOUSES

      • zach says:

        The trailer length is not generally regulated by any state in the US. It’s regulated by the DOT. I’m truck driver and these are basic laws every trucker needs to know. The length that states do regulate are when you haul double and triple trailers and/or are going into cities like NYC that are restricted to 48ft. If on city streets. All states require a CDL to haul any vehicle that has a gross combination weight (truck and trailer weight fully loaded) of 26,001lbs our more. The dimensions are spot on. No greater then 13’6″ tall and 8’6″ wide. If you go over that you will typically need a OD(over dimension) permit to haul. When in doubt call your state highway patrol and will inform you of the regulations you need to be aware of.

        • Tom says:

          The 13’6″ and 8’6″ is good for a class “C” license. If it is over then a Class “A” license may be required and possible oversize load cars included. If the Weight is good for 26000 lbs and over is class “A”. In California and towing RV and Trailer over 65′ requires a Class “A” license. A regular truck and Trailer is limited to 60′. Everyone in California has a CDL – California Drivers License. I guess if other states require a CDL you can always move here and get one. snk. With a class “A” license, a regular truck can haul a trailer pulling a second trailer if they want as long as it is under the load limits of the towing vehicle. I may get one just for the grins of it.

          • Michael Janzen says:

            This size can be towed by someone with a normal drivers licence. I’ve never seen any owner builder build a tiny house so big that it needed to consider length. I have seen park model rv manufactures build this large and larger.

  8. Douglas says:

    What are we building a tank?My home trailer build with 1×1 & 2×2 70 feet x 10 feet. Tiny house 8×18 building ultralight out side wall 3/8″ – 4’X8′ T1-11 in sid wall Maple Plywood (Common: 1/4-in x 4-ft x 8-ft 2×4 wall you could make Engineered wood floor trusses I-joist 1×1 with 1/4 Plywood or 1-in x 4-in wood

  9. Serene says:

    I really wanted to have a wider tiny home…semi’s are 10-11 ft wide…can’t you build a tiny home that wide? I wouldn’t build longer than 40ft so it wouldn’t be the full size of a semi….would l be able to do that without a permit or cdl?

    • Scott says:

      Semi trucks and trailers are NOT 10-12 foot wide. Being a driver since 1992, the width has NEVER changed.. 102″ (8′ 5″) wide. The only thing that has changed is the lengths. Just remember that the weight of your combo (pull vehicle & trailer) will determine if the license you possess will be legal for you to roll down the road. Best wishes.

  10. Dave says:

    Does anyone know the requirements for towing a 10.5’wide x 20′ long and 13′ high tiny home. Since the issue here is width (10.5 feet instead of 8.5m feet) do you need pilot vehicles and signage?

    Thx

  11. Ashley says:

    This is if the tiny house is built ON a trailer. What if it is built like a regular home and then hitched to ship it to its destination? Would it be better to at that point just build it on the property?

      • Deborah says:

        I wondering the same thing! I have been looking at nice portable buildings and thinking I could put it on a trailer and then design the inside, insulate, etc. So, you’re saying that is do-able?

        • Ron Anderson says:

          Every time you move this unit your are taking it into a category 1 hurricane and an earthquake simultaneously, as that is the amount of stress you are putting on the structure. You need to check to see if that portable building can handle the 50 to 70 mph winds you are going to encounter when you move the unit. After 35 years of building custom trailers, I seriously doubt the structure will take the load. Also the twisting that occurs when moving will pull the unit apart, if not properly put together. Please be careful as the last thing that you need is tor the unit to come come apart when driving down the freeway and your life is ruined because you kill or injure someone. All to save a few extra bucks over structuring something properly. Not putting down your idea, as its a great thought on the surface, just do your research.

          • Ron Anderson says:

            Honestly I don’t thing so, The risk is not worth the small amount of cost savings. 30 years ago maybe, but in todays world of attorneys suiting you for any and everything, its really not worth risking everything you have worked for ALL your life and That is what you are putting on the line. Something that moves, needs to be screwed together with special bonding agents that stay flexible. NO is not in my vocabulary as I have build some crazy stuff in my life. Like my original statement says “do your research” When you do you will realize this is not a good Idea, In my opinion.

          • Gina says:

            We built a tiny house on a 32ft trailer 8 ft wide 15.5 ft tall we are having a trucking company come move it to an RV park 3 miles down the road for atleast 5-10 years we need to get a special permit for the height, however I just want to make sure that these measurements are safe. Please email me at email hidden; JavaScript is required and let me know, I would love the advice.

  12. Robin T. says:

    i was wondering if you could post a 3 bedroom 1 or even better 1 1/4 (extra toilet closet) design or ideas…. Been sketching but very little available for a family of 5. (2 boys 6 and 7, and a 16 year old girl). Husband thinks I’m a little nuts but willing to entertain it if I show him how I can make it feasible. My idea is a small single room over truck bed with a bottom entry in front of a loft/bathroom area. But ANYTHING designed for a 3 bedroom area would be awesome! Thanks for the measurements, it helps my sketching in the meanwhile!

    • Deborah says:

      And no … I am not the same Deborah that asked that first question, although Deborahs must think alike!! lol

    • Mandie says:

      I’m currently working on a 3 bedroom tiny house. Mine will involve 2 trailers, not sure if that is an option for you. I got the idea from Tiny House Nation. Might not be a tiny house to the purists but I gotta do what works best for my family.

  13. 8x5 box trailer says:

    I am considering your finished trailer how it gonna be look like. Your measurement and size of your trailer seems very fit to your desired trailer. Expecting a much greater work and outcome from you.

  14. Freddy says:

    There is a bi-product of insulated steel panels which are the drops from where they cut out a slab door to put in a full glass this leaves a piece of foam with a steel skin on both sides then they route the foam allowing them to interlock. Then they screw the skin together and build walls with no studs or framing. They are 22×64 inches. 1 3/4 inch thick and are supposed to be r-19. These save space on your floor and are stronger and weigh 12 pounds per panel. You can see the buildings at tri-county insulated buildings Corbin ky. I don’t work there or anything. Just used them before and thought about the small house thing

    • Michael Janzen says:

      13′ 6″ tall by 8′ 6″ wide is the typical limit of a trailer without the need for special move permits. I don’t know how the commercial drivers license factors into it. I don’t think it does unless it’s a requirement for a special move permit. Probably varies per state.

  15. David Leigh says:

    There are some underpasses(bridges) which are less than 13 feet, so one had better know where those are before driving their tiny home on the open road.

  16. Paul says:

    I like the idea of a Tiny House. I’ve designed a couple. HOWEVER, building what are in essence NON-engineered fifth wheels (as in no qualified VEHICLE structural engineer involved in designing) is just silly. FAR better to get a fairly new, used (they devalue REALLY fast) 5th Wheeler and replace some of the appliances if you like. You will get much more for the money and it will last much longer.

  17. ArtisanJosh says:

    Great article & very intuitive thinking. I’m excited to see what you guys come up with next! Really Great Minds In Design!
    I’m currently building a 107sq Ft. Tiny on wheels. Very Tiny, LOL>
    It’s a dual-hookup system (Grid/Off-Grid) And the two systems do not integrate with each other in any way.

    Despite the many challenges of making that work in a real world environment, the build has gone GREAT !
    The ON-Grid systems are all up and running perfectly. All systems Go !
    I have however, yet to find a solution for water collection/storage/heating when OFF-Grid.
    My dilemma is SPACE. With only 107sq. Ft. I don’t have much to work with.
    Any ideas on a economical solution? I have enough space for a 5 gallon sized tank.

  18. Dufore says:

    I’m thinking about building a tiny house on a 32×8.5 duel axle trailer with two 14′ slideouts. Would a Ford Excursion 6.0 be a good two vehicle?

  19. Larry says:

    This website does not have their information correct in michigan the maximum length of a trailer that can be towed behind a vehicle without needing a CDL is 45 feet long on here they’re saying it can only be 40 feet long and when measuring a trailer it doesn’t go by the sides of the box it goes from the tongue to bumper

  20. David-Paul Newton-Scott says:

    Consider this all of you do you know if the Mona Lisa is painted on a canvass or a wooden board? Well there is now way of knowing until you touch it. All of you are worried about weight so get rid of internal lining such as plywood or worse drywall. Replace it with tensioned cotton paint it with emulsion paint and you will not be able to disinguish it from painted cotton. Also I hate cupboard doors make some really nice shelves with good quality edging. Weight can also be saved by having criss cross stud walls much stiffer so you can use thinner struts/studs eg Yurt.

    Come to think of it the Yurt has to be carried on horse back now that is light.

  21. David-Paul Newton-Scott says:

    Correction that should have read: Replace it with tensioned cotton paint it with emulsion paint and you will not be able to disinguish it from painted PLASTER.

  22. John Simon says:

    I ran across an Idea I saw in action when I traveled with a major carnival I will share after I talk to the Host to see if he thinks it’s worth it. Make your places MUCH BIGGER…..

  23. David-Paul says:

    In addition to my comments above concerning reducing weight use popouts like carnival people use.

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