semi trailer as an 8.5 x 45 (to 53) tiny house - yes or no?

So after some careful analysis of various options I think i'm wanting to try to build a tiny house out of a semi truck van trailer.  I seek public feedback or input - especially if people have more experience with trailers than me.  Really alot of the thinking is just as applicable to a single sealand container house - except i'm on wheels.  If the use of a semi trailer didn't work out i'd probably do something very similar with a sealand container instead.


Publically braindumping my thinking...

Why a house on wheels?  Because it makes code enforcement ____ off for a few years until I can get a better house built.  They dont have say over a travel trailer.  More time to research where on the land to put it, what to build thats code compliant, and save up resources.

It's also nice because if for some reason we got a financial windfall, we might buy different land (instead of just cheapest possible land it's started parking on) and migrate there.  

Why not an existing RV/travel trailer?  Because I should be able to upinsulate to a better level of insulation, making a four seasons suitable tiny house.  My preference is to use 4x8 used styrofoam sheet like from walk in freezers.  Or maybe I just find a reefer trailer as probably a better solution already foam insulated.

Why not build a tiny house right from the frame up?  More work, more planning required, and less 'anonymous'.  I'm already starting with a metal outerbox that's resistant to wind, weather, I mean they drive 75mph with them all the time so....  heck I could park it in a trailer storage facility and nobody would care, whereas a 'house' that looks like a house i'm not sure if I could do that.

Why not a mobile home?  Yes wider is more room but then you need permits to move on the road.  A semi trailer could just be up and hauled by any class 8 trucker - possibly including myself if I get a CDL which i'm strongly considering.

Why not other trailer types to build inside like a race car trailer?  Because for the money and the market a semi truck trailer seems cheaper than anything for the square footage with a decently tall internal ceiling.  I've seen them for sale for $1000 or less - I can't touch any other enclosed trailer for that let alone something this size, and around 400 square feet is probably tolerable.



This would really be a 'shotgun shack' - no hallway, just maybe two walls with a door in the middle separating a kitchen/bath area at the opening, a living room area, and a bedroom area.  I'd need to make or improvise some kind of separate emergency exit from the bedroom in case of fire for safety.

Think i'd use a minimally raised floor in the kitchen/shower area instead of sinking all plumbing and pipes under the floor of the trailer.  It will be inside the insulated area in case I have to work on it in the winter.  No crawling about under things to diagnose a problem.  So things like drainage pipes out from the shower and sink would just go horizontally 'out the door' when parked in place.

I like the idea of the trailer being as unchanged as possibly visually from the outside so if the outer doors were closed you'd barely or not at all know it's anything but a trailer, even if we lack some window space.  Because if it's parked for weeks when we can't visit the homestead i'm hoping a ratty looking trailer is less of a theft target than a clear obvious 'home'.  I'm unsure how to make the 2nd exit door from the bedroom (in case of fire) without altering the look however.

Think of a recessed wall about a foot inside the outer semi trailer doors, where you have a conventional door, window AC unit, window to the outside directly venting from the kitchen/shower separately from a vent feeding the bedroom/living room area, and things like water/electric connections at the bottom.  I"d have to build something to connect to water, sewer, power, and to provide a walk up stairs and entryway/boot/jacket room of sorts.  The possibility of extending this room to allow a 2nd trailer parked somewhat (not exactly) near to the first isn't off the table, but the idea is to keep them as separate 'residences' not connected as one.  Like we might do this if a friend moves in with us but wants his own space.  It's not as energy efficient as one space but cost and being paid for ASAP counts for alot.  It's just to get by and may be very temporary/getting a different set of stairs and entry room built elsewhere on the property then moving the trailer there.

One goal is to not change the roadworthiness of the trailer - so that it can be up and moved, on short notice if need be, somewhere else.


Even tho it's not a large living space, we hope to stick up a quonset ASAP afterwards so that both workshop time and some recreational time can be spent in there.  We might live like this 1 year or 5 depending on how things go.  I'm going to be trying to getting thru grad school for the longer range of that time if other plans don't work out ahead of then.

Your logic is sound…other than the $1000 trailer being road worthy. The $1000 trailers usually need at a minimum tires and brakes. But they are still cheaper than sea containers.

It is not uncommon for smaller van trucks to have side access doors, less common on semi trailers but they do exist. Not hard to add and look like it belongs. Other option for emergency exit would be a skylight.

Brian said, " especially if people have more experience with trailers than me.

I once rented a semi-trailer to use on my property.

Loaded up with my household belongings.  When I check on it the mattresses were all waterlogged.  The thing leaked like a sieve.

Since you want to be able to move it "on short notice" will you have to hire someone to move it?

I wouldn’t.  I find the floors to be within reason …sometimes.  Other than that, they are very light weight.

If you were to make a loft bed in the nose of the trailer, a skylight could serve as a second exit, and with a rope ladder would be quite easy to get out of. Plus, storage under the bed loft. In fact, skylights may be useful for the rest of the building as well, to maintain structural integrity of the sidewalls and retain the discrete appearance of the outside. Looking for a trailer with a side door, as others have mentioned seems like a good idea. Who doesn't want a kitchen door?

I’ve picked up a few school buses and they are awesome for moving and storage as the motor is built in. You have to watch for windows that like to leak. They go for $2000-$4000 for something with a decent running motor.

Semi trailers are high and relatively lightweight. In other words, a perfect sail. On highways with strong wind gusts, they are sometimes blown over on their sides. Depending on the location, I would consider a cable and anchor system for safety.

Your logic is sound…other than the $1000 trailer being road worthy. The $1000 trailers usually need at a minimum tires and brakes.

Trailers are inspected regularly, just like the trucks that pull them. Without a current inspection (brakes, air lines, tires, lights, frame, springs, etc) you may find it difficult to get anyone other than a towing company to move one very far. The $1000 ones have generally been declared 'un-roadworthy' by the DOT, the owners, or both. That could be due to things like tires or brakes, but those are normal expenses for a trucking company, so usually there's also bigger issues like leaks or structural integrity.
As for insulation, using rigid board can lead to moisture issues from condensation between the metal and the sheets. Best way to go (not exactly cheap) is to spray foam the entire inside 2" thick (or more). 2" will give you about r-15. It would also be money well spent to have someone thoroughly inspect the roof for leaks or weak areas. Skylights done correctly could be a good option if you don't want windows, but you also need to consider some sort of venting for airflow. Skylights are not a great option on a flat roof unless you have a curb, which is a built up frame for the skylight to sit on. That will add to the height, which could be a consideration when moving it.

The refer boxes have a little insulation.  Not at lot.  Those are made to have the refer run pretty much constantly.

I think it's definitely an idea worth considering.  Those moving van trailers have a drop deck in the center part and would be much easier to get in and out of.  I've never been in one but the ones I've seen on the road look like they might be built fairly stout.  Get online at truckpaper or auctiontime and look at moving van trailers.  I sure think they have possibilities and have toyed with the idea of using them for a bunkhouse or camp on leased land.

Don't think that  just because it looks crappy it is less likely to get broken into. It could be more at risk because vandals (and kids) think no one will bother to do anything if they have some fun with it. (Fun can include being burnt out). I know this from a past experience. Even rural areas are at risk. Also, anything locked is considered to have something valuable inside - really good locks indicate something REALLY valuable inside.

If you just buy a commercially built RV that is made for winter sporting, all the wrinkles have already been worked out. Buying a used one from a family that used it lightly, will bring the price down - and if you don't crap it out, when you are finished with it, you'll probably get nearly as much back as you paid for it. You always need to consider the value of your own time, and what you'd get for the object if you needed/wanted to sell later.

Easy to transport and easy to find a parking space to keep it when not in use. Any RV with a pull-out can have a wood burning stove installed pretty easily, and in that case good versus perfect insulation is less of an issue. Any woodburner will keep any RV toasty.

You also need to make sure - for anything you intend to move later - that you keep the running carriage maintained. Easy to ignore, much harder to fix later (again, I know this from past experience).

I'll just try to resummarize responses (showing that i'm reading, and appreciating the feedback, thank you) while adding new stuff at the end.

R Scott - I think i've seen $1000 trailers advertised as roadworthy, which I assumed meant working tires and brakes.  It's apparently legal to run a semi trailer with just one set of tires (not duallies on all four hubs) tho obviously not at full weight and then a blowout is more dangerous. (maybe not as bad if there's still front and rear axles to share it with and you're moving empty to start)

This brings to mind though - how would one maintain brakes on a semi trailer so that they'd work if you hook it back up 1-3 years later?  Or will they seize up and become a serious problem the way cars parked outside will rust out discs and sometimes seize up drums, are trailers any more resilent against that?  Is there any way to 'exercise' things like hooking up an air compressor periodically to cycle things or should I assume extended parking will mean four brake rebuilds and a tire swap?

Any idea if there's a way to preserve tires as long as they arent near the end of their age lifespan?  Besides put the axles up on blocks to get weight off and cover to shield from sun I mean.
Adding a side door that doesnt look out of place - idea noted.  

Anne - i'd like to get a Class 8 CDL, or have people on call I could hire as plan B.  Getting other trailers to use as storage or even converting one to be a form of office is also on the list.  (a separate 'living space' that i'd only use during the day so it doesnt take all space from the 'house' trailer)

John - I don't know why floors that should hold tons of dry goods should be a problem, i'm not putting a piano in there I mean, though if heavy bookshelves a problem - noted.  I'd think the frame rails should be dang strong?  Just need thicker floor at most?

Casey - a skoolie is one of the Plan B's.  So is a sealand container, obviously minus the wheels.  See same problems down below.

Julie - I thought the main reason for $1000 trailers (when I looked) is no longer being the desired 53 foot limit as one big factor (plus they will be old by age cuz we've had 53's for awhile), like I remember they were 45 footers or something, and someone hauling at 5mpg wants the best legal use of space possible.

You bring up moisture issues - THIS IS A BIG QUESTION FOR ME and I don't know the right answer.  The simple answer might be "get a reefer", even if theyre not perfect insulation maybe they start with enough to add thinner styrofoam in addition.  But how is styrofoam on houses different?  Do I add a vapor barrier?  Then doesn't it just condense inside or outside that not really solving the problem?

What about a different insulation?  What if I just put up drywall (possibly without even studs, i'm not planning on punching the wall here) and just filled behind it with rice hulls?  Those are super lightweight, insulative (perhaps less than styrofoam), supposed to resist moisture problems.

Mary - vandal risk noted.  I know a commercial RV is better - i'm unlikely to afford better.  If a semi trailer doesn't work, other options are other 'boxes' like the skoolie, sealand container, etc.  The value of my own time is part of why I want to start with a weather/rain/windproof box - seems easier to upinsulate and add some things to that.  If I absolutely absolutely cant, the fallback Plan C is to build an A-frame on a skid so it can at least be moved around the property, possibly if narrow like 12ft jacked up and put on a flatbed to move.  But i'd still like to explore steel box options a bit more.

Break in risks will be what they will be - a house with smashable windows is no better.  My biggest concerns so far seem to be insulation condensation and keeping the running gear running so it can be re-moved later, or there's less point having it start on wheels to begin with.

Brian Shaw wrote:I'll just try to resummarize responses (showing that i'm reading, and appreciating the feedback, thank you) while adding new stuff at the end.

R Scott - I think i've seen $1000 trailers advertised as roadworthy, which I assumed meant working tires and brakes.  It's apparently legal to run a semi trailer with just one set of tires (not duallies on all four hubs) tho obviously not at full weight and then a blowout is more dangerous. (maybe not as bad if there's still front and rear axles to share it with and you're moving empty to start)

Any idea if there's a way to preserve tires as long as they arent near the end of their age lifespan?  Besides put the axles up on blocks to get weight off and cover to shield from sun I mean.
Adding a side door that doesnt look out of place - idea noted.  

John - I don't know why floors that should hold tons of dry goods should be a problem, i'm not putting a piano in there I mean, though if heavy bookshelves a problem - noted.  I'd think the frame rails should be dang strong?  Just need thicker floor at most?

What about a different insulation?  What if I just put up drywall (possibly without even studs, i'm not planning on punching the wall here) and just filled behind it with rice hulls?  Those are super lightweight, insulative (perhaps less than styrofoam), supposed to resist moisture problems.

My brother and his first wife had trucks.  And, I've had other family members who drove for a living.  So, I've been around trucks a bit.

Single tires - They make an extra wide tire.  Sorry, I forget the name.  They are made to take the place of duelies.  This might be what you are seeing.

Preserving tires - Keeping them out of the elements and the weight off them will slow their decay.  But, rubber decays over time.  That is why there are legal limits on how old they can be for a licensed shop to put them on a vehicle.  There is a manufacture date pressed into each tire so the shop can tell how old it is.  I don't remember how to read the code.  It's been too long.

Floors - Most of what goes in a semi trailer sits on pallets or is in large boxes.  The weight is spread out over a fairly reasonable area.  A lot of your furniture sits on fairly small legs.  Different trailers are rated for different pounds per square inch.  It is a valid consideration.

Side door - Lots of refer units and moving vans have side doors.  I would think it would be worth looking into.

Cooling - I saw a trailer turned into an office years ago.  They built a roof a foot or so above the top of the trailer kinda like a carport.  The guy said it made it WAY easier to keep cool in the summer.

My daughters friend built a tiny home out of a refer trailer. Things I didn't know was the r-value differs depended on what the trailer hauled, produce, less r-value than frozen, so that might be a consideration. Single guy so 2/3 of the trailer is living 1/3 is a mini shop. The plywood walls and roof once sanded looked nice. His choice was because it was more mobile than a container and the insulation and interior walls were already there. He's a finish carpenter by trade and the woodwork/cabinetry he has added is incredible.