Teardrop and tiny trailers

In the context of building a trailer, there are two major controlling aspects:

• Trailer features drive the size of the trailer
• Materials drive the construction techniques

In many ways, trailer lightweighting strategies borrow from the ultralight hiking community:

• Define your targeted activity
• Define the minimum basis set of capabilities or features needed
• Don’t pack (build) your fears
• Always pursue novel strategies for gear / construction

What do most trailers do? Well, most RVs are equipped to handle a family and provide a lot of creature comforts, a “home away from home”, as base camps. This makes them big, heavy, and not very mobile. Teardrop trailers are minimal little rigs that are nice for touring while you camp at established campsites with bathroom facilities and water. This makes them extremely limited in features. Campervans are designed to be minimal but self-sufficient movable homes that can access remote locations.

In my case, the target activity is: A trailer that can extend our hiking range by giving us a place to stay at remote trailheads and/or on the way back home. Thus, the trailer needs to be a self-sufficient, but minimal, home that is able to handle two to three nights of use without a resupply. It doesn’t need to handle a week; and it doesn’t need to be a home-away-from-home. In addition to being lightweight because we don’t want to sell either of our cars, light weight is also good for accessing remote locations. The trailer will be used primarily in summer, but could extend into shoulder seasons.

Minimum basis set of features: Start with a clean slate, and start adding in features that are needed, rather than taking a full RV (or other example) and reducing features you don’t need. In our case, we need a space tall enough to stand up in, that we can take a “Navy” shower in, that has a toilet, a bed, a table to dine at, a sink, and a burner to boil water on. It needs to be weatherproof and adequately ventilated. So what does that mean? Plumbing - water tanks (clean, gray, and maybe black), water pumping; propane fuel; a waterproof area.

Then what? Do we need a fridge? (Maybe… cold beers are nice after a hike.) A TV? (Nope!) An oven or microwave? (Nope and nope!) A furnace? (Maybe, shoulder seasons could get chilly at altitude.) A water heater? (Yes please.) Electricity? (Maybe, if we put in electrical items…) Lights? (Oh - yeah. Duh. So electricity is a must.) A separate dining area versus the bed? (Nope, convertible spaces are cool.) Does that toilet need to flush? (No, it can be a dry toilet - bye bye, black water tanks!) Will there be air conditioning? (No - way too resource intensive.) Will there be space for dogs? (Well, they can sleep in the trailer when we sleep, but they can’t stay in there when we’re gone.)

Construction techniques are probably the biggest place that people build their fears. This trailer will be moving down the highway at 60+ mph, going over bumpy roads… so the initial thought is to build it like a house+tank. Three-quarter inch plywood floor! Wood 2x4 framing! Screws everywhere!

Well… sure, you could do that… but it’s going to be H.E.A.V.Y.

Cue a piece of wisdom from a teardrop trailer forum. A wise person said, a trailer is more like a plane or a boat, not a moving house. Enter… marine and aerospace wisdom!

Guess what construction method is often used in these cases - not plywood with framing, but composites. Lots and lots of composites. Sandwich panels and fiberglass abound. Bonding happens with adhesives instead of screws.

What is a sandwich panel, you ask? A sandwich panel is a multilayer building panel that consists of a relatively thick layer of foam panel bonded on both surfaces to a thin layer of rigid, solid material such as plywood. The thicker the foam layer, the stronger the panel. The high strength-to-weight ratio comes from increasing the stiffness of the panel (by making it thicker) while minimally increasing its weight.

What about fiberglass? Fiberglass is a composite material consisting of glass fibers embedded in a polymer matrix. Strength is provided by the glass fiber, while rigidity is provided by the polymer (typically epoxy or polyester - more on that later). The glass can come in a woven sheet or a chopped strand mat (unwoven). Woven sheet is strong, while chopped strand mat is weaker but more formable. Fiberglass can be used to provide strength or simply to provide waterproofing. The more glass there is, the stronger and heavier.

DrBohr and I decided to go with a sandwich panel construction (edit: foam and plywood) with two layers of exterior fiberglass for waterproofing and structural integrity.

In the next post, I will talk about materials and component selection for our trailer.

In Part I of this series of posts, I explained the motivation for building a custom ultralight trailer and its basic requirements. As a reminder, it needs to be 1500 lbs (or preferably less), with an interior bed/dinette conversion, shower, toilet, and (very) basic kitchen, and tall enough to stand up in. It should be able to handle about three days without resupply.

In this post, I will talk about understanding what’s already been done by people already, because reinventing the wheel is dumb.

We (my husband, DrBohr, and I, CherenkovBlue) initially had no real idea of how we wanted to execute this trailer, only a vision of what we wanted to achieve. So we started by educating ourselves voraciously on what people had already done. There are several good resources, including the Teardrops and Tiny Trailers subreddit, the www.tnttt.com forum, and books on the topic. These forums are incredibly helpful for finding information about construction techniques from DIYers. Many people there are building teardrop or squaredrop trailers, in which the trailer consists of a living space with a bed inside (and really, only a bed and some cabinets), and a fairly extensive kitchen that opens to the outside world on the backside of the trailer.

Teardrop trailers are quite light, but not what DrBohr and I are exactly interested in (rats, we can’t just adopt a blueprint…). What we’re after is a place to sleep and shower in at the trailhead, with the ability to boil water for coffee and rehydrated meals. Teardrop trailers typically do not contain toilets or showers and are not tall enough to stand up in. They are often constructed out of 4’x8’ sheets of material, with one sheet per side wall, to give a sense of the size. The kitchens also tend to be overkill for the purposes of DrBohr and I, and their back hatch tends to be a source of water ingress when it rains.

There are multiple vendors of teardrop and tiny trailers, including TAG and Scamp (and many others). TAG trailers are very similar to what DrBohr and I would like to build, so their layouts and interior solutions are a very useful point of reference. Many people also mod their TAG trailers, providing some great hacks for personalizing the living space and improving utility. Scamp manufactures fiberglass trailers and almost hit our weight limit for their smallest trailer, but not quite. These trailers are tall enough to stand up in and do include showers, toilets, beds, and kitchens. However, they tend to be slightly (or more than slightly) over-featured, such as including televisions and microwaves, that DrBohr and I are not interested in, which also increases the weight.

Campervan conversions are a rich source of information and work with many of the same limitations that this trailer will have. Being a full living space in a regular vehicle rather than a large-engine, tow-specialized vehicle, weight and dimensions are a key concern. Because campervan conversions frequently include showers and electrical systems, many online resources are available discussing plumbing and wiring. They also include interior kitchens and bed-to-dining area conversions to maximize utilization of interior space, which is in line with our trailer needs as well.

In Part III of this series, I will discuss Lightweighting Strategies, or Challenging Your Assumptions.

About a year ago, husband and I embarked on a journey to design and build our own custom teardrop/tiny trailer within some very specific design constraints. We backpack a lot and want to stretch our range further, as tent camping at trailheads isn't always possible, and having a trailer to come back to after a hike to shower and rest would be amazing. However, both of our cars have limited (or no!) towing capacity. Did you know a Subaru Crosstrek with CVT has a rated towing capacity of 1500 lbs? I didn't!

So, we wanted an ultralight trailer that was going to be better in all ways than what we could do with tent camping. That means:

• Max towing weight (loaded) 1500 lbs, preferably 1200 lbs
• Interior bathroom including shower and toilet facilities
• Interior kitchen space
• Table and seating
• Comfy bed
• Tall enough to stand up in the middle/in the shower

Cue a ton of designing, redesigning, and investigation of construction techniques and materials. I will get into the details in upcoming posts!