Need a temporary, affordable, all-season, and comfortable dwelling?

Try building a greenhouse with a tent inside.



Introduction:

The idea stemmed from my love of modern backpacking tents. They use a 'floor-to-ceiling' rainfly that covers the tent. The tents themselves are made primarily of screen to keep insects out and stay well ventilated. My rainflys are a greenhouse cover in the winter season, and an opaque, heavy-duty tarp (used billboard) in the summer months.



History:

Like most inventions, this was born out of necessity. I needed a dwelling that was temporary, but solid enough to withstand the harsh climate of northern Minnesota. I was saving to purchase my own peice of land, so the idea was to build something that could be dissassembled and moved easily(being that I was squatting on family property). The project started as a canvas tent on a wooden platform, but quickly transformed into something completely unforeseen. I took inspiration from seeing hoop houses used as storage sheds, and the availability of a used billboard supplier in Minneapolis (cedar ave & E. 28th st), not to mention the crazy, backwoods ideas of some good friends.



The Nitty-Gritty:

-The Frame: of the greenhouse is 18 gauge chain link fence top-rail, available at any hardware store. I bent the hoops myself with the help of a jig I bought (http://www.lostcreek.net/) and purchased the connecting hardware from www.growerssupply.com/ Hoops are doubled towards the middle in 2 places: the stove pipe exit, and the peak of the canvas tent. Each end of the hoops are secured directly to the sides of the floor.

-The Spine: is a 1/2" steel cable (dumpster score) that is anchored fore and aft, runs through the maple logs on either end, and is anchored on both sides. The idea was to stop a tree from crushing me in my sleep during our epic november storms (think edmond fitzgerald).

-The Floor: is built like a house. Green-treated 4x4's, and a platform of 2x6's and 3/4" plywood. This rests on concrete discs I made by pouring quick-crete into 1 gallon ice cream pails. I wanted this to be semi-permanent, so pouring pilings was out of the question.

-The Rain-Flys: consist of 6 mil translucent greenhouse fabric in winter and covered by a 15 mil cross-stitched tarp (http://www.billboardtarps.com/) in summer. I used grommets to create folded pockets on all side of both materials in which I inserted toprail through the length and rope at either end that is cinched and tied off to the platform. Both of these have withstood gale-force winds without a budge.

-The Tent: is a GP Army canvas tent. It was a purchase of convenience. Some friends of mine had lived in it for a number of seasons, and were getting rid of it. This tent is a hexagon shape, however a square shape may be more space efficient, but not as heat efficient. I attached it to the platform by using 8' 2x2's along the bottom of each wall and screwed them down. The center pole is replaced by a threaded dowel attached to the Frame and bolted from the inside until taught. All of the guy lines were then attached to the frame in appropriate places to alleviate the need for internal poles.

-The Lonely Window: was the greatest thing I did to this thing. After a long winter without one, it made a huge difference. These tents are made to be blacked out (no light in or out) so depending on electric lights in the middle of the day sucked and made it feel very cave-like. I framed one of the south facing walls and added a single pane window (garage sale score, $1). I also wired an outlet and light switch, and hung a fire extinguisher while I was at it.

-The Gable Ends: are a simple 2x4 frame using lots of 45 degree bracing. The aft looks similar. I think my design is pretty, but there are all sorts of ways to do it. Browse greenhouse photos for awhile and they all start to look alike. The main entrance door is on 2-way hinges (dumpster score) so it feels very saloon-like. The big door is hinged from the top to create an awning when extended.

-The Stove: is run through an existing high-temperature rubber pipe hole in the tent and through a thimble attached to the frame (where the hoops are doubled 1 foot apart). I used a tar-tape from growers supply to adhear the greenhouse fabric to the thimble that's made for just that purpose.

-The Rain Collection: is a vinyl gutter mounted on and under an 'angle iron' shaped 2x4 and 2x2 that run the length of the tent (it's better just to look at the picture). It pours into a 40 gallon water barrel and overflows into a 55 gallon former-bbq-sauce barrel. Allows me to wash clothes and dishes without hauling water (just the potable stuff needs to be hauled).



The Performance:

I will preface by saying that this is a tent. It wouldn't be fair to compare it to a permanent structure.

Wind:The structure of the tent has withstood 70 mph winds without a budge, which leads me to believe it could take even more.

Snow: loads were a large concern, however, the warmth of the greenhouse keeps the snow from sticking to the peak and it slides right off.

Humidity: was another concern, but running a wood stove (even within the canvas tent) is enough to alleviate most of the dripping from inside the greenhouse plastic.

Fire: has always been on the top of my safety concerns, and the stove pipe/stove setup is safer than alot I've seen in wooden structures. Aside from the floor itself, there are not many combustables in the surrounding area. The tent, greenhouse plastic, and carpeting (dumpster score) are all fire retardant and the stove rests on a tile patch work. Plus a fire extinguisher on hand.

Insulation: value is probably 1/2 (maybe 1/4?). The outer shell is quite wind proof which reduces alot of drafts, but does little for heat retention. The canvas tent has an inner cotton liner that I also suspend comforters from for added insulation, but it's definately not an insulated house. An oversized woodstove it necassary to keep warm on cold February nights.

Solar Gain: from the greenhouse can be quite powerful. On a clear day at 10 degrees, it can be upwards of 45 degrees within the canvas tent.



I'll be happy to field any questions, and thanks for reading.

