And, Speaking of Domes…

Jennifer and I have long talked about setting up a rudimentary greenhouse in the back yard. The growing season here in Oklahoma is such that a greenhouse is highly useful for getting a head start when late frosts can be unpredictable. Currently, we do still live in town (much to our chagrin), and city code limits building construction without a permit to 100-square feet and without a permanent foundation. In the past, I’d thought about framing in something with used lumber or pipe, and wrapping the whole thing in heavy gauge Visqueen, or similar clear, plastic sheet. Recently, I began thinking about framing up a geodesic dome out of 2x4s or 2x6s, with the clear plastic stapled to the inside and outside of the framework. That would give plenty of light passage with 3.5″ or 5.5″ of airspace for natural insulation – probably plenty to buffer against those last few late frosts in the beginning of the Spring.

Shortening pi to 3.14, and working out the math, I find that a 11.2-foot diameter dome would be precisely 100-square feet, so I’d likely want to take the footprint down to an even eleven square feet, just to stay on the safe side. That would give us just about 95 square feet that we could use for sprouting seeds, growing things that are otherwise difficult to grow here, and even stretching out the Fall growing season to a degree. Using this nifty utility, I can see that an eleven-foot diameter, 5/8 dome can be made with 165 boards of just over two feet, using 61 joints. If my math serves me, that would give us a ceiling height of about 6.5-feet in the center, which is plenty for us short people.

This guy got the same idea, and built himself a nice little greenhouse dome, and he even worked out the angles that the boards should ideally be cut to. It looks like there are all sorts of choices for fancy hardware connectors, but the gentleman mentioned above industriously used steel strap and PVC pipe for jointing. In fact, there are lots of organized resources for anyone who might want to build a dome. Given the size of the lumber that this project would require, I bet I could get used lumber for next to nothing if I keep my ears open. In fact, I wonder how close to free I could build this bad boy. I may have to go haunt Craig’s List to see what’s available…

11 thoughts on “And, Speaking of Domes…

  1. There’s a site you can buy what is essentially a tent frame with clear plastic on it to use as a green house. They recommend setting 4x4s into the ground and attaching the tent frame to that. Now I’m not going to pay their prices, but it occured to me that its often fairly easy to get tents cheap on craigslist….

    • Are you thinking of Teksupply, which sells all sorts of Ag doodads and building supplies?

      Building a greenhouse out of the film and using something like 1″ PVC pipe for the frame would go up fast, and if designed right, could be disassembled without breaking it.

      • You’re both right, of course. It would be cheap and easy to build a PVC pipe and plastic film greenhouse. But then, I wouldn’t have a dome! :P

        • Would PVC stand up to prolonged exposure to heat, cold, sun, wind, and rain? I would think that PVC would be prone to cracking/shattering after a few summer/winter cycles, with some of those gentle Oklahoma breezes thrown in the mix…

        • Do keep the PVC/Film idea, it makes for cheap, easily stored cold frames(which only wind up being uses a third the year anyway).

      • I wasn’t, but thank you for pointing me to their site!

        I’m drawing a blank on the other site, I didn’t bookmark it after looking at what they offered for what they wanted for it, but I made mental note of the idea….

  2. Just FYI- pallets are free, all you have to do is break them down.

    Or you could get dunnage at a (large) construction site that has large steel pipe.
    I made a kick-@ss book case out of used oak 4x4x6ft wood the plumbers were going to throw away.

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