How I Built a Hoop House

This fall I really wanted to take our farm to the next level so I decided to build a hoop house. I searched the internet for countless hours trying to learn how to do it…. for as cheap as possible. I came to the conclusion that there are a million ways to build a hoop house so you just have to build one that is right for you. I will show you how I chose to build mine. Along the way I will try to share things that I wish I had done differently.

For those of you who don’t know a hoop house is kind of like a cheap greenhouse with a few differences.

A hoop house does not usually have a heat supply, it is heated by solar gain. However, some people do heat their hoop houses with a small heater on exceptionally cold nights. It is usually considered a temporary structure because it is relatively easy to take down and move to a new location. Hoop houses usually have two layers of greenhouse plastic separated by a thin layer of air to insulate the structure. A high tunnel is very similar to a hoop house, some people even use the two names interchangeably, but technically a high tunnel only has one layer of greenhouse plastic.

A greenhouse usually has a heat source which can be anything from electric, propane, wood fire, etc… They are considered permanent structures, and are usually built out of sturdier and more durable materials.

The first thing to consider is what to construct your hoops out of. Many people have used PVC pipe for their hoops. After much deliberation I chose to go with metal instead and here is why: I saw way to many horrific pictures of mangled PVC pipe twisted and contorted by the wrath of mother nature. PVC pipe is strong enough to make a hoop house….. until it snows a lot, or the wind blows hard, or you look at it the wrong way. Another reason PVC pipe is not my first choice of building material is because the chemicals in the pipe actually cause the greenhouse plastic to degrade faster if they touch. 6 mil Greenhouse plastic is supposed to last 5 years, but if you build your hoop with PVC it might only last 3 years. If you do decide to use PVC get the schedule 80. It is cheaper and stronger. You can also try to put some kind of barrier between the greenhouse plastic and the pipe like felt or duct tape or paint, it will slow down the plastic degradation. Instead of PVC I chose to use chain link fence top rail. You can buy it at any hardware store for relatively cheap, and it is easy to bend. I luckily had some laying around that I was able to recycle which saved me a good chunk of change. I did find that not all top rail pipe is created equal. The stuff I had laying around was pretty old, and like the saying goes, “they don’t make things like they used to.” The old stuff must have been an alloy of steel and aluminum because it was much stronger than the new stuff I bought from the hardware store. If you can find chain link top rail that is not pure aluminum I would chose that instead. Pure aluminum top rail is too flimsy in my opinion. Another thing to consider is the length of the top rail. I bough the new pipe in 10′ lengths. The old stuff I had laying around was in 20′ lengths. The 20′ length is a much better option. It is stronger and easier to work with. If you want an even stronger hoop you can use 1″ x 1″ square steel tube with a clear coat. You can get this in 20′ and 24′ lengths and it would be even stronger than the chain link top rail. It is comparable in price as well. If you use the square tube you need to buy/ make the Hanley style Hoop Bender.

The second thing to consider is how to construct the hoops. You can buy this nifty hoop bender from many online retailers. I bought mine from Johhny Seed’s for about $40. At first I though I could build one of these myself but I failed miserably. Do yourself a favor and spend the $40, it will last you a lifetime.

Next up is the ground stakes to support the hoops. I used 5/8″ rebar. It is cheap and readily available at your local hardware store. Chop it into 24″ lengths, two for each hoop.

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Next is the greenhouse plastic. You can order this online through several retailers, I ordered mine from Johnny Seeds. I ordered a 24′ x 65′ 6 mil greenhouse plastic sheet, it cost about $150. (Ouch) The plastic is a little expensive, but it should last 5 years. This is enough plastic to make a 12′ wide x 50′ long hoop house with end-walls.

Next are end-wall materials. I chose to make mine from recycled 2x4s and greenhouse plastic. You will also need hinges, a locking mechanism, pipe strap and some screws.

Next comes the wiggle wire. This is the amazing product that allows you to anchor the greenhouse plastic to the end-walls without creating any holes in it. You can also take the plastic off and put it back on again without damaging it. I ordered mine from Johhny Seeds. You will need about 40′ of wiggle channel and 40′ of wiggle wire.

Finally lets talk about the perlins and hip boards. These are used to make the hoop house sturdier and can be made from a wide range of materials. You can use more top rail pipe, or you can use wood, or you can use metal wire, or you can use nylon cord, or you can used recycled baling twine. Guess what I used? That’s right, Baling twine! Why? Because its free and I feel better about myself when I can recycle something. If you want to use bailing twine find a farmer or someone with horses or cows and ask them for some. After a bail of hay is used the twine is basically useless so they should be happy to give it away for free. One word of advise: if you have the choice, use twine from a 1 ton bale rather than the smaller bales because it is stronger and more durable.

Now lets talk about the steps to building it.

Its always a good idea to prepare the ground that your hoop house is going to cover before you build the hoop house. It is much easier to till, haul compost, level, create raised beds etc before the structure is built. I cleared all of the plants and added a few inches of composted steer manure, organic fertilizer, and Azomite before I started building. I was not able to till yet because my tiller was getting fixed. I finally got around to tilling after the structure was complete and it would have been a lot easier to do it in advance!

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Next mark all four corners of your hoop house. Take your time to get it nice and square. I used rope to create a perimeter around the four corners to check for accuracy. You can also measure both diagonals to determine if the layout is square. Then pound in your 24″ rebar stakes every 6′ down both lengths of your perimeter. You can put your hoops closer or further apart than 6′ depending on the material you use to build your hoops and your own climate. If you get a lot of snow your going to want to put them closer together, but if you live in a mild climate you might get away with spacing them father apart. Pound the stakes until there is about 6″ above ground level. It is also a good idea to angle the stakes 15* towards the center of the structure to make it easier to slide on the hoops.

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Next its time to bend the hoops using your hand dandy hoop bender. When bending make sure to take your time and bend only a couple of feet of the pipe at a time. If you slide the tube 3 or 4 feet through the bender between each “bend cycle” you will end up with an uneven curve. You only want to slide the tube about 2 feet between each “bend cycle.” It is a good idea to have someone help hold the pipe level on the opposite side of the bender while you bend it so it doesn’t sway up or down.

Next slide the ends of the hoops onto the rebar stakes. You will have to put a little force the bend the hoop a little further to fit on the rebar. This is good because that tension creates strength and stability.

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Next its time to add the Wiggle Wire Channel to the hoops on the end wall hoops. You will need to buy Tech Screws, these are self drilling metal screws available at any hardware store. I started at the peak of the hoop and attached the channel as I bent it to fit the curve of the hoop. It is a good idea to have a ladder and a second person to help attach the wiggle channel to the hoops. It is a little difficult to install, but it will make things much easier in the end.

Next I had to make some kind of strapping system to hold the plastic to each hoop. I ended up using more recycled bailing twine, and I have been happy with the results thus far. Here is how I did it. Take a piece of bailing twine that is at least 45′ long (you can tie multiple pieces together) and tie it to the rebar stake on one side of the hoop house. You want to tie it so one side of the twine is about 5′ long and the other side is about 40′ long. Then tie a loop at the end of the 5′ long side. Tie a rope like this to each rebar down one side of the hoop house. It is important to make sure that you tie the knot on the rebar under the “hoop pipe” so that it cannot slide up the pipe later on.

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This picture illustrates how the rope should be tied. (Pretend that the rope on the Left side is 40′ long… you get the idea)

Next, I chose to complete my end wall door. There are a lot of options when it comes to building end walls, and it really depends on how you will use your hoop house. I chose to create a door on one end and a solid wall on the other. I chose to use more 6 mil greenhouse plastic to cover the surface of both end walls and the door. The greenhouse plastic is stapled between two strips of wood. (When building doors make sure it is wide enough for your wheelbarrow, tiller, tractor …. to fit through it) I used two pieces of 2×4 measured and cut to fit between the hoop and a piece of metal I used for the base of the wall. You could use more wood if you wanted, but make sure it is treated as it will be in direct contact with the ground. I used pipe strap to connect the wood to the hoop, but you could use old drip tape and some screws. (pictured below)

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I pounded two T- posts into the ground to strap my 2×4’s to for each end wall. I highly recommend this as it created a lot of extra support for the end walls. I then made a simple rectangular door with some hinges and a sliding lock. I decided to give the door a little more protection from the wind by adding a small piece of 1×2 as a “door stopper”.

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For the next step you are going to want to secure as many people as you can to help apply the greenhouse plastic. The more people to help the easier it will be. Make sure to do this on a day that has little to no wind because the plastic has a lot of surface area that can act like a giant kite. If you are not careful you and Toto could be carried away.

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If you are using greenhouse plastic to make your end walls now is the time to pre-cut them to size. make sure you cut a piece that is the height of your hoop plus 1′-2′ extra. Start on one end of the hoop house, locking the plastic for the end wall and the “tunnel” plastic into the channel with the wiggle wire. Both sheets of plastic should overlap a few inches and fit into the wiggle channel. After the end wall sheet and the long tunnel sheet are attached to the hoop unroll the plastic down the side of the structure. Unfold the plastic and pull it up and over the hoops. This is where extra help would be nice. Once you get to the opposite end pull the tunnel sheet to remove most of the slack. Ensure that the plastic is placed evenly over the hoops and there is extra on both sides for anchoring later on. Attach the tunnel sheet and the second end wall sheet with the wiggle channel and wire.

20151022_184436Next throw the long piece of bailing twine/ cord over each hoop, feed it through the loop on the opposite side and throw it back over again. Once the rope is back to the original side feed it through the loop and cinch it tight and tie it off.  Repeat for each rope on each hoop. These ropes are what hold the plastic to the structure so you want them to be fairly taught. Extra slack in the plastic can cause flapping and tearing during heavy winds.

I used bailing twine for my perlins and mid rib. (pictured above) These are supports that connect all of the hoops together which increases strength. When you shake or pull on one hoop all of the other hoops help to brace and support it. You could use pvc pipe, wood, metal tubing, metal cable, …

Next pull the plastic around the perimeter down to the ground and cover with dirt. This creates a seal to hold in the warm air and keep the wind out. In the summer months you can pull the dirt off and slide the plastic up the hoops to allow air to circulate through the tunnel. Be careful if you live in a rainy location as the bunched up plastic can collect water and bend/ break the hoops.

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This is a picture up the inside of the hoop house after it was completed and the ground had been tilled. I chose to make three beds and two walk ways. Each bed was 3 feet wide and each walkway was 1.5 feet wide.

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Here is what the hoop house looks like today. You can kind of see the raised beds and walkways. I have laid three strips of dip tape down each bed. I burned holes in landscaping fabric for each row, this will hopefully keep the weeds at bay. The white cloth is called agribon. It is used to hold the heat in during cold nights and allow 80% of light to pass through it during the day. I have just planted ranunculus, anemones and tulips with plans to add dusty miller and icelandic poppies later on.

I have to open the door during the day because it gets too hot. Even when it is only 40* F outside it can reach 95* F inside. Much too hot for ranunculus and anemones! At night the air temperature inside the hoop house is almost the same as it is outside. However, the ground is still warm from absorbing solar energy during the day which allows the plants to survive in sub zero temperatures. So far the hoop house has held up well under snow and wind. Looking back I wish I had installed a temperature controlled automatic window opener on both end walls because it gets too hot inside on sunny winter days. Univent Automatic Vent and Window Opener

 

Total Cost for my Hoop House:

Greenhouse Plastic                                  $150

Wiggle Channel and Wire                       $50

Hoops (most recycled)                            $45

Rebar for stakes                                         $20

Bailing Twine                                              Free

Wood for Endwalls (Most recycled)      $10

Pipe strap                                                       $5

T posts                                                            $18

Tech Screws                                                   $5

Wire  (On Hand)                                          FREE

——————————————-

Total                                                               $303

Cost of similar sized Hoop House Kit :    $2421

Savings of about $2100! Can’t wait to build another one 🙂

 

Some pictures in this post are from johnnyseeds.com

 

 

 

 

 

 


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