There are as many trailer types as there are types of people. The questions we wrestled with:
Do you want a house on wheels, or just the freedom from debt, and the ability to live and build tiny as you like?
In other words, are you better off building a <120 square foot house to lower costs and avoid building permits? The International Building Code (which is really a misnomer – it’s used pretty much only in the US and Canada) specifies that permanent structures under 120 square feet and 11′ average roof height do not require a building permit, thereby fulfilling most of the goals of tiny housers except mobility. If a tiny permanent house is really what you want, but you didn’t know you could do that, I recommend you read The Hand-Sculpted House by Ianto Evans about cob house construction. Don’t know what cob is? Then you definitely need to look into it. Oregon cob is awesome, and a true green building material!
Length – most tiny houses that are lived in full time are between 16 and 20 ft long (trailers are measured by deck size, not total length, so a 20′ trailer may actually be 24′ feet long). Maximum road size for a trailer with a fixed load, such as a tiny house, is 13’6″ high from road to rooftop, and 8’6″ from side to side without needing special licensing or permits. I believe this is all states, but check into it.
Axles – how many, what type, and how much weight will they carry? Single axle trailers are for the super-light-living tiny housers, or for vacation teardrops or tinies such as this one. The axles are generally rated for somewhere between 3,500 or 5,000 lbs GVW, or gross vehicular weight. This means that the weight of the trailer must also be counted when you are figuring the weight of your house carried by the axles. The weight rating depends on a few things, such as the thickness and shape of the axle, and can often be told by the lug pattern on the wheels – 5 lugs usually means 3,500 lbs and 6 lugs 5,000, but the safest way to find out is to look on the axle itself for a label or a stamp with the mfr info. You also want to know what kind of suspension the axles have – traditional steel leaf springs, or Torq-type axles, which contain rubber and will age and crack as all rubber does, but bounce better while they last. I don’t know of any commercial trailers I looked at that had Torq axles, so probably not something to worry about. There are also drop axles, which generally allow the deck to be lowered by 4″, but interfere with maximizing the space between wheel wells, and give you less clearance under your house but more height to work with.
Style – There are flatbed utility trailers that have the deck mounted between the wheel wells, or over them, some with dove tails on the back. There are also used RV trailers that have had the upper parts removed that you can sometimes find or salvage, or custom trailers made just for tiny houses!
Flatbed utility – If you get the utility type mounted between wheel wells, you either have to contend with framing in the wells that stick out from your walls internally, or having a house that is very narrow built between the wells, but you get more head room for a loft if you want it (remember, 13’6″ for road height).
Over-the-wheels decked trailers – The over-the-wheels flatbeds are easier to frame in and nice and wide, but you lose a ton of head room so you might have to compensate by having a longer trailer. More air movement under the house could also cause excessive cooling if you live in a cool climate, but might be good for a hot one.
Dovetailed trailers are a pain, but you can use them if you’ve got the patience and time to frame them.
Used RV frames might work, but they are often heavily rusted and you would have to check out the condition of the axles/wheels and the weight rating. They don’t always have heavy duty axles suitable for a heavy tiny house. Interested in salvaging an old RV for a trailer? See Zyl’s post on the tinyhouseblog: http://tinyhouseblog.com/tiny-house-concept/recycling-old-rv-trailers/. He gave a really realistic table of the costs and benefits.
Custom tiny house trailer – Awesome. We originally bought a regular 10k 18′ utility trailer, but after reading Go House Go and visiting all the people we could living in tiny houses, we decided the drop deck style with extended cross members was the best idea. That way, you get the benefits of the over-the-wheels deck stability with the preserved head room of the typical flatbed.
– Electric lights, electric brakes, and an emergency breakaway kit. Just because it has electric lights does not mean it has electric brakes. The emergency breakaway kit is a tiny battery with a mechanism that is wired into your existing axle brakes. The mechanism has a cable which you attach to your vehicle just like the chains. If your dear little house should ever come unhitched while being towed, come unplugged, and the chains break, it will trip the little mechanism when the cable is pulled, and engage your trailer’s brakes for you, so you don’t have a runaway tiny house going too far. Really important, don’t you think? You can buy the kits online, or if you are lucky enough to have a trailer company that specializes in tiny house or heavy trailers, they might come stock or install it for you.
–Look for quality. Do the welds look like crap? Don’t buy it. How about the electrical system? Does the electrical harness look sketchy? Does it work? Is the trailer frame made out of I beam, C channel, or box beams? (in order of quality and strength). How far apart are the cross-members? Fewer is better for keeping the trailer light, but closer together is better if you want to carry more weight. Usually you want them no farther than 24″ apart, but 16″ o.c. is overkill. Is the electrical system safely tucked into the trailer frame, or is it flopping around to get torn loose and run over? Do the tires look worn or old? Is it rusted? If it is, is it surface rust you can remove and paint over, or do you have structural damage? Does it have a warranty so if you have problems you can get help? Does it have a grease system that is easy to use so you’ll maintain your axle bearings properly? Also, is it registered? Is the title clear of problems (e.g. is the current seller’s name the last one listed on the title? If not, be afraid!)
What You Don’t Need:
– Railings of any kind above the decking, “sticker pockets”, ramps, or full decking (you may save some of the boards to use in your subfloor and bottom plates if you don’t mind the horrific chemicals in pressure treated wood, or if you were lucky enough to get a cedar deck)
For reference, our trailer is a dual axle HD 10k, which means each axle can carry 5,000 lbs, for a total of 10,000 lbs weight. In Oregon, anything over 8,000 lbs is considered a “heavy trailer” and must be registered as such. The trailer guy we bought ours from said over 10,000 lbs you need a special permit – I don’t know if that is for all states or just Oregon, so check with your Dept of Motor Vehicles. Our trailer itself weighs around 1,430 lbs, which leaves us with around 8,570 lbs of house/stuff weight to work with. It came with an emergency breakaway kit, squared off wheel wells for easier framing, maximized space between the wells and a maxed-out road width of 8’6″. The best part for us is that the cross-members, or the welded joists between the framing, are actually welded below the frame, so that we can have a nice insulated floor that is 6″ thick without losing all the head room, and the cross members extend out flush with the wheel wells, so our walls are weight bearing on steel, not the suspended subfloor built on top of the trailer frame like in the Tumbleweed designs.
A word about cost:
DO NOT SCRIMP ON YOUR TRAILER. Really. We are not made of money either, so believe us. We bought as much as we could secondhand, but the trailer is where you should splurge, and it should be the biggest expenditure you make on your tiny house. If you buy a crummy trailer, you will worry about your house forevermore, especially when moving it, even more so if you don’t/can’t get insurance on it. Save up and buy the best trailer you can. You can always upgrade your appliances or your furniture or even your windows but you can do little to improve your trailer once it is built. We were stupid, and learned the hard way. Learn from us. We really liked Iron Eagle Trailers, if you want a place to start, as they do really high quality work and they went the extra mile for us. The cost was worth every dime.
Hope this helps you as you ponder buying new or purchasing that Craigslist gem!