Hoop, there it is (remix)!

NFI & MOG's hoophouse in Winter 2011

Back in the DC area and back in 2010, Bea & her friend Josh hatched a plan to build an enormous shared hoophouse that would provide enough bench space for both the Neighborhood Farm Initiative & My Organic Garden to start their seedlings.  This hoophouse project became a huge pain in the rear (understatement of the century!), ultimately involving plenty of contentious arguments, lots of blood-sweat-and-tears, being stalked at home by our landlord, being evicted after the thing was finally built, and finally an ER visit.

Lots of plant babies growing in Spring 2011

Josh is pretty good about knowing to cut his losses when he's behind, but Bea is stubborn as all get-out and determined to resurrect this structure “someday, somewhere, somehow."

Well folks, that time is now & that place is here, the Fixettwell Farmlet!  Bea traded a couple of months of free labor in exchange for owning this monolith outright, and so we included our hoops in determining the size of moving truck we would need -- THE LARGEST ONE POSSIBLE!

handymath.com is a brilliant tool!

It worked out surprisingly well, with the hoops fitting perfectly along one side just like the math said!  Who ever said geometry class has no real-life applications?!

Winter 2011 after a long, COLD workday at the hoophouse 

Back on Hoophouse 1.0, we began construction the weekend after Thanksgiving and finally had everything closed in by the end of January, with all the benches built up & functional by mid-March.  We were working around a bunch of conflicting schedules at the time, so the workdays were set in stone and not weather-dependent -- meaning there were a whole lot of REALLY COLD workdays that winter!  When we set about to start building Hoophouse 2.0 this January, I promised Chris that we wouldn't ever work on the project if it was below 40°F.  So that means we're using every scrap of daylight on the random nice days we've had lately to get this thing constructed in time to start our transplants!  It's been surprisingly easier the 2nd time around, despite only having the two of us as laborers.

Hoophouse building supplies -- yes we moved all this here!

After moving, our hoops spent a couple months hanging out at the chicken coop for no particular reason...

We learned some things the first time around, and we also decided to make some modifications to improve the design as we rebuild.  Since it's January, of course most days have been below 40°F and so Bea has somewhat single-mindedly spent hours researching best practices for hoophouse-building and come up with some hopefully cool & functional ideas to make our hoophouse more useful as a year-round growing space.

As we rebuild, we'll be adding:

• roll-up sides (our first hoophouse just had top vents--really ineffective!), 
• double doors on each end wall, 
• automatic heat-powered vent windows, 
• a rainwater collection & distribution system, and 
• a bike-powered irrigation system!

We're excited to share each improvement as we get them built out.  For now, we've just completed the bare bones structure so we'll start with sharing that.

How to Build a Hoophouse Part 1

Our skeleton of Hoophouse 2.0 is the same as 1.0 so some of these photos are from 2010-11.

Step 1: Site your structure.

The first step of any building project is going to be figuring out the best spot to put it.  This should involve calling the county/Miss Utility to figure out where any underground utilities, well, or septic tank may be.  This also should involve scoping out how much sun your site gets -- you'll want at least 6-8 hours of full sunshine, and don't forget that your trees will be shadier in summer when they've got leaves on.  In an ideal site in the northern hemisphere your hoophouse would be oriented with the long sides running east-west in order to maximize the southern sun exposure.  Other factors to consider could include the direction of prevailing winds which could influence ventilation or if you live somewhere with very strong winds, might mean orienting it accordingly so that the structure doesn't catch the wind and blow away.  Yet another consideration is building the structure on as level ground as possible.  Or you could do what we did, and just go with what will look coolest on Google satellite maps.

In any case, you want to spend a significant amount of time staking out your corners and ensuring they're square.  Remember Pythagoras' theorem:

Our tapes measuring both diagonals -- perfect!

Have a couple of tape measures longer than your hoophouse -- in our case, our dimensions are 20'x50', so we have (2) 100' tapes.  This makes it a lot easier to measure the diagonals and square everything up.  In our case, 20x20 + 50x50 = sq root of 2900, or ~ 53.85', or 53' 10 1/4" (across the diagonals).  Approximately.

Once you get your corners set, pound in a scrap of rebar or another sturdy stake that you can tie string to and measure off.

Step 2: Install ground stakes.

Our ground stakes are cut to about 3' long out of a long tube of 1" galvanized steel toprail -- usually used in installing chainlink fence.  You'll need twice as many ground-stakes as you have hoops since each end attaches to one stake.

You'll need to acquire a very large-headed carriage bolt so that as you pound in your stakes you won't squash the top edge.  You put the bolt in the top of each post, and pound them in about 5'-6' apart -- in our case, we're doing 5' spacing so that our 11 hoops end up covering 50'.  Set up a string with a line-level attached between your corner stakes, and also a long tape measure pulled taut so you make sure the posts remain in a straight line, since where you pound them in will determine the shape & placement of your entire hoophouse.

Use a post pounder upside-down once it gets too close to ground level, or you can use a sledge hammer if you have good aim.  A level with a magnetic strip was helpful in making sure the stakes remain plumb while pounding.  The stakes should have at least 12" sticking out above ground when you're done.

Step 3: Install self-tapping screw stops.

While you still have your level string set up, drive a self-tapping hex-head screw (rated to cut through steel, not just sheet metal) approx 12" from the top of each stake -- or along the level string if your ground isn't level.  The hoops will slide over the stakes and their weight will rest on these screw heads until they're attached.

Step 4: Bend your hoops.

Volunteers work on bending the hoops for Hoophouse 1.0

In our case, this was done in 2011 and so we didn't have to redo this.

Chris was the only full-time hoop-bender!

Basically, the hoops are 30' long (to make a 20' wide hoophouse) and come as 1 3/8" 14-gauge pipes.  So you build a jig that has the correct curve (google this) and then feed the straight pipes through the jig, bending as you go.  When you're done bending, the hoops ideally all have the same angles to make a nice quonset shape.  In our case, there was a team of volunteers subbing in and out of the hoop-bending process, so some are overbent and some are underbent.  Eh, you get what you pay for!

Step 5: Install hoops.

In 2010, it was all hands on deck to get the hoops installed

Slide each hoop over the groundstakes -- this sounds a lot easier than it may actually be.  In 2011, it involved teams of volunteers contorting themselves into weird configurations trying to bear all their weight down on the hoops, or alternately standing on logs to raise the other end up into the air.  Unfortunately it was all-hands-on-deck so we don't have any photos of this amusing process!

Our volunteer laborer, Sir Ratchet Straps.
I think he did about 90% of the work.

This year, just Chris & I and some indispensable ratchet straps were able to get all the hoops over the stakes.  Ratchet straps are definitely worth about half a dozen team members.  The hoops should slide down all the way so that they're sitting directly atop the screws.

11 hoops in place & it's not even dark yet!

Step 5: Install more self-tapping screws.

Once you get your hoops in place, drive another self-tapping screw through both the hoop and the ground stake behind it.  Chris becomes enamored with his Christmas present, an impact driver.

Bea is a little nervous about ladders.
She says it's a fear of heights, but this
ladder only gets her about 3' off the ground!

Step 6: Install purlins.

These are 1 3/8" 17-gauge galvanized steel tubes that are connected to the hoops to help give the structure stability.  One goes straight down the center at the top of the hoops -- you attach it using cross connectors generally used for chainlink fencing.  We also installed one purlin on each side, 5 feet down from the center.  As you connect the purlins, measure that your hoops are in fact 5' on-center apart (or whatever spacing you used when installing your ground-stakes).  Sometimes they don't sit quite plumb and may need encouragement from a sledge hammer.

The straps came in handy for revising the bend
of some of the more misshapen hoops

Since the purlin pipes are usually 10' or 20' in length, you need multiple pipes for each 50' run.  One end of each section has a male “swedge" built into it (a 6" section or so that's a smaller diameter) which you slip into the female end of the next pipe.  Then attach a self-tapping metal screw through both pipes to hold them together.

All 3 purlins successfully installed!

You want all screw heads and connectors to point down/inward so that they don't stick up into the plastic covering.  Expect to be standing on a ladder for a few hours working upside down above your head installing all these connectors!

Step 7: Install base boards.

Around the base of your hoophouse, install 2x8s as baseboards.  This gives you a solid base that your plastic can either attach to or rest on if you have roll-up sides, and it provides stability for the whole structure.  

Use galvanized heavy-duty plumbing straps to wrap around the hoop and screw into the base boards on each side.  Do the same thing on the corners.

For Hoophouse 1.0, we had an 8' opening on the side so two 6' boards coming in toward the center that we'll use to build the endwalls off.  Despite reworking the framing for the endwalls, we kept the placement of the 6' boards to build off of.

All baseboards installed!

Step 8: Tie on monofilament.

Monofilament helps support plastic between the metal frame

This step is optional if you have a single enormous piece of greenhouse plastic that you'll be using to cover the hoophouse.  For us, Hoophouse 1.0 had top vents and so we have 4 overlapping shorter pieces of plastic.  For best results, we'd purchase a new single piece of greenhouse plastic, but when we unrolled what we had it still looked totally functional, and a new roll costs upward of $300, plus given that the plastic only lasts for 4 years we decided to stick with what we have until we have to replace it in a couple of years anyway, at which point we will purchase a single piece.

Luckily, back when we demolished
Hoophouse 1.0, Bea thought of tying
individual strands of monofilament
into loops with bread ties, which
made untangling 1,000 times easier!

We used a variation on a
hangman's knot drawn through an
extra loop.

So for now, we need the monofilament which will help to support the plastic over the span between hoops.  A single piece could be pulled taut enough it doesn't need monofilament, but since the middle two overlapping pieces will only be attached on the sides, you gotta spend a few hours tying this stuff on to the end hoops.

Bea continues getting over her
fear of ladders

This monofilament is no regular fishing line; it is super heavy duty -- 2.5mm thick!  The goal is to tie each line onto both end hoops as taut as possible with approx 3-6" spacing between lines.  Before, we covered the whole hoophouse with lines of monofilament, but this time we stopped 5' from the ground since Hoophouse 2.0 will have roll-up sides.  This also worked out great because when we disassembled Hoophouse 1.0 in a hurry, we had to cut some of the lines & wouldn't have had enough left to run as many lines as last time.

Steps 9 & 10: Build end walls & cover with plastic!

We haven't gotten these done yet because it's super cold again!  We also will be changing up how we build the endwalls, so that seems like another post for another time!

Hoophouse 2.0, January 2014