DIY Hoop House Greenhouse Design and Build

As a kid, I tried to make my own solar ovens. I fashioned old windows together, and put pans of water inside to heat. They usually sucked, but these experiments spurred my fascination with greenhouses. Like my grandfather, I love growing things, and would imagine creating an endless summer indoors where I could grow exotic plants. Last year, my childhood fixation was revived when we visited the earth-ships in Taos, New Mexico. This summer, I finally decided to design and build my own greenhouse.

The new Crazy Kicks HQ

Why not to build a passive solar greenhouse

I actually wanted to build an earth-ship. The passive solar concepts are too cool, and I even started collecting windows. This design usually has one side facing south with windows angled to collect heat from the sun, and another side that is insulated and contains some thermal mass to store the heat.

In the winter, the sun is low in the sky, and all of the solar energy is trapped by the angled windows. The thermal mass heats up during the day, then puts off heat all night. In the summer, the sun is high in the sky and doesn’t come into the windows, keeping the space cool. This passive, self regulating design keeps earth-ships a comfy 70 degrees year round.

A passive solar earthship we saw in New Mexico.

I love the idea, but when contemplating my own design, I found a few issues.

First, an earth-ship is a serious structure. I would need to build insulated rear walls, build up thermal mass, and install some big ass windows. With limited room in the yard, and neighbors close by, I wasn’t too keen on erecting a big permanent structure.

Second, a passive solar design is perfect for us, but not necessarily for the plants. The design is intended to reduce sunlight coming in during the summer to keep things cool, but I still want to grow in the summer. I plan to start heat-loving plants like tomatoes and cucumbers earlier inside. They wouldn’t be happy if they stopped getting sunlight later in the summer.

Designing a snow proof hoop house

Once I dropped the passive solar concept, I concentrated on designing a basic, cheap, sturdy, and movable greenhouse. Based on those criteria, I settled on a hoop house. After poring over the internet, I found an awesome resource from the University of Illinois extension that outlines different types of hoop house designs.

After hours of R&D, I had these scribbles to show…

I followed a lot of the design principles from that paper. The ribs are spaced 4′ apart, the end-walls are braced to add rigidity, and the sides are screened in and roll up for ventilation.

Being in New England however, poses another issue. Hoop houses have a tendency to collapse under heavy snow. This is less of a problem if you plan on heating the greenhouse because some of the snow would melt. But I plan on leaving mine passive, and just using it to extend the seasons.

New hoop houses use a Gothic arch to help shed snow. I saw a local farm go to this design after their semicircle Quonset-style greenhouse collapsed. This would be a great idea, but since I planned on bending my own hoops, I wanted the shape to stay basic. So to help account for snow load, I added a 2x6x16 beam down the middle.

Hoop house materials

I designed the structure around materials that are available at any big box hardware store. The ribs are each made from two sections of 10′ chain link fence top-rail. The end-walls and base are made from pressure treated lumber. To keep cost and waste down, I optimized around dimensional lumber sizes and ended up with a 12’x16′ footprint.

This is all the scrap I was left with, and even ended up using the two longer pieces.

I connected the metal ribs to the wooden frame using a combination of electrical conduit straps and 3″ deck screws which I drove through pre-drilled holes in the pipe.

I had to order the materials for the covering online. The plastic is a special UV treated 6 mil greenhouse film that is supposed to last 4 years. It’s held in place using wiggle wire channel lock. This stuff is awesome. You jut pull the plastic over the channel and then wiggle the wire into place. The wire acts as a spring pushing the plastic against the channel keeping everything secure.

Wiggle wire channel lock

I attached the channel lock to the frame using self-drilling screws. I was surprised how easily they went into the metal frame.

DIY hoop house hoop bender

While you can buy a hoop bender for about $50, I don’t like having single use tools or spending money. Instead I made one myself. All you really need is a semicircle to bend the pipe around. I took a scrap 2×6 that I had laying around, tied a 6′ length of string to the foot of a table and then pulled it tight to scribe a 6′ radius curve on the wood. I cut the curve out with a jigsaw, and then lag bolted it to a stump in my yard with an opposing 2×4 at the end.

DIY hoop house hoop bender

This worked well enough, but if I did it again, I’d make a smaller curve than what’s needed. The pipe tends to bend back a bit after being pressed around the curve, so it would have been better to give my pipe bending template something smaller than the 6′ radius.

Bending on the bender

I also would have made a flat surface for the bent part of the pipe to rest on. As I moved the pipe through the bender, it tended to droop and not all of the bends ended up in the same plane. Some of the the pipe got a bit twisted and didn’t lay flat. While a bit wonky, they still work fine.

Building the hoop house

Once I had my hoops, I set them up around the yard to test out locations. I settled on a spot that was partly shaded by trees in the summer, but should have full sun in the winter. After squaring up the posts, I prepped the ground with my tiller and pulled out rocks.

We have big rocks

I assembled the end walls in my garage so I would have a relatively flat surface to work on. Then, with Mrs CK’s help, hauled them out to the yard.

Most days I work in my bathing suit.

At this point, I leveled everything using temporary bracing, and bolted the frame together.

Sturdy frame

Once the frame was solid, I added the channel lock for securing the plastic, and some chicken wire to keep out critters when we open the sides for venting.

I was pretty excited when the plastic showed up. It was a windy day though, so I waited for a calm day. It’s tough enough getting the plastic into place without the wind trying to take it.

Plastic secured with wiggle wire

As soon as we started putting the plastic on, the heat picked up inside. It’s incredible how much heat this thing traps on a hot day. I kept the sides closed the first day as a test, and my glasses instantly steamed up every time I went inside – it was working!

So far it’s still been too warm to close the vents

The cost of building a DIY greenhouse

I like to recycle and source most of my project materials for free. Earlier this summer, I built a treadle feeder for the chickens and a new compost bin using materials I pulled out of a dumpster.

For this project, I did source one of the ribs from an old chain link fence I took down, and the door is made from recycled wood I pulled from a dumpster. Unfortunately, most of the other materials I had to buy new. Still, doing everything myself saved a good bit of cash.

The chickens didn’t care that I made their treadle feeder out of trash πŸ™‚

The materials for the frame, including lumber, fasteners, chicken wire, and chain link fence railing cost about $350. The greenhouse film and wiggle wire channel lock set me back another $300. That’s about $650 to build a solid – hopefully snow-proof – 12’x16′ greenhouse.

Now to extend the growing season

Once everything was set, I planted one of the fig trees I started this spring, lettuce, kale, tatsoi, green onions, carrots, and turnips. To make things easier, I ran a power cord and hose underground to the greenhouse.

Don’t forget the party lights!

While I haven’t had the weather to truly test it out yet, I already love my new space. It’s not just a haven for our plants, but also an extra space for me to get some sunlight and have my hands in the dirt when it’s too cold outside. I’ve been learning a lot about growing my own food lately, and am looking forward to exploring gardening in a whole new dimension.

15 thoughts on “DIY Hoop House Greenhouse Design and Build

  1. Ok, Mr Crazy Kicks, your hoop house is amazing! You truly are an inspiring rennaisance man. Thanks for all you continued informative and well detailled, fantastic posts. I love and read them all while quietly observing your progress. You inspired me to retire early from full time trauma nursing, this past July, and I finally pulled the trigger. Best thing I ever did! Still love and share your pizza recipie all the time> Best pizza, hands down! πŸ™‚

    • Oh, wow! Congratulations, that’s awesome news πŸ™‚

      It’s starting to cool off here, and I just made my first round of pies for the season. It’s probably good I don’t have an outdoor oven, because those homemade pizzas are addictive! I’m glad you’re enjoying the recipe as much as we do πŸ™‚

      As always, many thanks for the kind words!

  2. That greenhouse looks dynamite! Fortunately it doesn’t snow in our area, so the growing season in Texas is fairly long. However, this does make me wonder if there’s a version of a greenhouse we could make to shield plants from heat, which is our issue in the plant-killing summer heat.

    • Thanks! You definitely have the opposite problem πŸ™‚

      You could use a hoop house with some shade cloth for protecting your plants. In that case, I’d build something much cheaper, since you don’t need to worry about snow. A simple caterpillar tunnel with open ends would cut it.

      Another cool option I’ve seen, is planting some fruit trees in the garden. A tree would add shade, pull nutrients from deeper in the ground, and feed the top soil with leaves in the fall πŸ™‚

  3. I’d be interested to see how the plastic holds up to snow. I friend of mine built something similar. It shed the snow until we got one of those really misty sticky types of snow that froze to the plastic. Once there was a thin frozen layer other snow stuck to it like velcro and it caved in. How many feet of snow to you get in a season?

    • Yeah, I’ve seen a lot of greenhouses collapse around here… The structure itself feels quite solid, there’s hardly any deflection when I hang from it, but we do get quite a bit of snow. It really depends from season to season, last year we hardly had any, but a few years ago we were getting 30 inches at a time several times in a row.

      I tried to walk the line between over-engineering, and building it to handle some serious snow. While I like to think I found a good compromise, only time will tell πŸ™‚

  4. Nice hoop house Mr. CK! I’ve made a couple of these over the years and they really are surprisingly affordable.

    In my own hoop-house experiments here in the PNW, I didn’t realize vastly improved results, so I’m not sure what I was doing wrong.

    If you were to purchase all the produce you grow in the hoop-house, how long do you expect the payoff period to be?

    • I actually just started keeping the greenhouse closed these last few days. It’s been really nice to hang out in there early in the morning when the sun first comes out warming up the space. I’m already noticing the plants inside are growing a good bit faster than the ones outside.

      I’m also in the market for some thermometers so I can try and plot out the actual differences. Should be a fun experiment.

      As far as pay-off period, it would depend on crops. I could probably pay it off in a few seasons if I was intensively growing higher priced greens, or just in one season growing some pot. But because of laws, I can’t grow pot, and I’ll be planting a lot of less profitable crops with my greens. I still think I’ll get my value out of experimenting with it though πŸ™‚

  5. Yeah, that’s amazing. Great job.
    I’d love to have a greenhouse, but we’re in a condo right now. We have a really nice community garden. I’m pretty sure they wouldn’t approve a greenhouse, though. Someday…

  6. Awesome hoop house and great DIY info! Growing up I was very fortunate to have access to my grandfather’s 16 x 20 greenhouse. I’m sure I acquired my love of growing things from him as well. I have fond memories of hanging out in an 80+ degree greenhouse on a sunny day in the dead of winter. I was even growing cherry tomatoes during the colder months.

    I think you’ll be okay with the snow, you may want to manually clear it off when a foot or more is expected. I built a hoop structure with gray plastic conduit over my koi pond so I don’t have to have to heat it in the winter. While it lasted 2-3 winters, the PVC conduit was too flexible to handle much snow load. I am going to rebuild it this year using some tips learned from your article πŸ™‚ I never would have thought about your custom hoop bender.

    You’ll probably be able to grow some cool weather crops for a good part of the winter in there. If you were to add some thermal mass like rocks or barrels of water, you might be able to extend it even more. Nice job!

    • Thanks for the vote of confidence, Jeff!

      I will keep the snow cleared, but we’re going to Costa Rica for 3 weeks this winter, so some snow may pile up. Hopefully not too much.

      Now that I have the beds in, I’ve started to bring in some old pavers for the pathways to add some thermal mass. I was considering a barrel of water too, but I’m starting to get greedy with my planting space. I probably should make some space though to try it out…

      Thanks for the insight on your greenhouse experiences πŸ™‚

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