Hoophouse: The frame goes up

Time to start the real construction! My parents were visiting today and I hijacked them to help get the hoophouse frame up. They ended up helping me the entire afternoon, but we got a lot done.

I did most of the work getting the base together and level before they arrived. The spot in our garden where the hoophouse is going isn't quite even, so I had to dig down a bit on two sides to get the base level. I attached the 2'x8' hemlock lumber together with some long lag screws.

The EMT hoops will attach to the base on the inside of the base with strapping and lag screws. For the end hoops, I had to bend one end of the strapping and screw it into the end of the 16' base side before attaching the base ends.



This hoophouse shouldn't be going anywhere, but it'll act like a big sail and we get some string winds, so we also added four 4"x4" post anchors. They're screwed to the base and buried about 18" down. This should give the entire building some more stability.



With the base done, I marked off the locations for the hoops: every 27" on center, except the middle two hoops which would have a 30" separation. My parents held the hoops plumb and in place while I attached them with the two pieces of EMT strapping. This part went pretty fast and soon we had all eight hoops up. To add more support to the hoops, I drilled 1/4" holes through them, between the two strapping pieces and installed a lag screw to really secure them to the base.

The 16' ridge purlin was made from two 10' 3/4" EMT conduit pieces. I cut one piece to 6' and spliced it with a 10' piece. Installing the purlin was also pretty easy since I had the connectors already in place, but it was still a two person job and we had to make sure the hoops were evenly spaced at the ridge before tightening the connectors.

With just that, the hoops were feeling pretty stable, but I had fashioned some diagonal braces to attach on the sides to add more rigidity. These braces were made from 5' sections of 3/4" EMT. I pounded about 1 1/2" flat on each end with a sledgehammer and bench vise. Note that the flattened sections are perpendicular to each other because one end is lag screwed to the top of the base frame and the other end is attached to a hoop with a self-drilling tek screw.

We installed a siderail/kneerail (made from two 1"x4"x8' boards spliced in the middle) on each side, attaching them with more EMT strapping and 3/4" wood screws. The strapping pieces on the end had to have one end bent around and screwed into the end of the board because we don't want the board sticking out beyond the end hoops. The siderails are multipurpose. They're used to tie the hoops together and will have wigglewire installed on the outside to attach the plastic to. They will also be used when installing the roll-up sides.

The hoops were now done, on to framing in the end walls. I had another 2"x8"x12' plank and cut that in half and nailed it to the middle inside of each base end. That gave me a 4"x6' base top to frame off of. The end frames are very simple with four vertical 2x4s and one header 2x4. The door frame was set for 36" wide. All the 2x4s were attached with framing nails for metal framing brackets and wood screws. The header 2x4 was attached to the end hoop with a modified piece of EMT strapping.











This guy is licensed to drill!

More spring maintenance

I got back in the bees today with a few objectives.  I had to refill their half gallon feeders with syrup and remove the inserts from below the screened bottom boards.  I checked on hive D, the weak hive that I added some egg and brood frames to a couple weeks prior.  Turns out they're doing great now.  I saw the marked queen and plenty of new eggs that looked good.  The hive's honey supply has also greatly decreased as they've been building up.  I went through a some of the other hives a bit to check on things.  No swarm cells yet (yah) and all the hives appear to be building up well with good eggs and brood.  I found the queen in hive A.  She had a faint mark from a previous year, so I marked her again to make it more visible.  I swapped out a couple old frames with some new foundation frames.

I've also been working on a new swarm trap.  It's basically a homemade nuc box as it's the same size and will hold five deep frames, but will have a larger entrance hole.  It's about done.  Need to paint it, get some hardware cloth for the hole to keep birds out and then hang it in a nearby tree with some old frames in it for bait.  With the rate the bees are going, I wouldn't be surprised if we get a couple swarms this year.  Not sure what we'll do with them since we don't have any more hives, but I'm sure someone would take them off our hands.

Hoophouse progress begins!

Bending the conduit.

Top pipes are 3/4" EMT, bottom left is 1/2" IMC and bottom right is 1/2" EMT. Notice how the IMC fits in snugly, but the EMT is very loose.



Here's how the conduit is "spliced" together. I use a 10" or 12" piece of 1/2" IMC that will go inside the 3/4" EMT. Mark the middle of the IMC piece and insert it into one of the EMT pipes up to the mark. Drill a 1/4" hole through the two pipes a few inches back and insert a 1/4"-20 x 1 1/4" bold through it to hold it. Repeat for the other end of the splice.

The top ridge angle has a hole through it for a purlin connector. Place a 1/4" carriage bolt in a 1/4" drilled hole and tap it down with a hammer a few times and you get a nice squarish hole that will result in a pretty smooth top where the plastic will go. The middle of a 10' EMT pipe is marked before bending it so we know where to drill the hole after the bend.




A finished hoop.

Hoophouse resources

Here is a list of some of the websites I found with hoophouse information.


(PDF) A very informative and useful write-up from the University of Vermont
HoopHouse Greenhouse Kits (company)
How to Build a PVC Hoophouse for your Garden
Rodale Institute: Detailed instructions for building your very own fieldhouses
University of Tennessee Extension: Agricultural Building and Equipment Plan List
Hightunnels.org (part of a USDA project, good resources page with links)
(PDF) Brian Olsen High Tunnels from Alaska
Little House on the Island blog (emt 16'x20' backyard greenhouse, they were an inspiration for my design)
Gardenweb.com forums, partway down lots of good pics from Indian Valley Farm
(PDF) Alabama Cooperative Extension Hobby Greenhouse Construction
(PDF) Portable Poly Pipe High Tunnel Hoop House Construction Plans (lots of great pics in this)
PVC Hoophouse Construction (from Maine)
Steve's Greenhouses (some good pics)
Eden House hoophouses (from Maine!)

Hoophouse design

A little background. Jeannine and I both love to garden. We've had two small gardens in our front yard for five years now. We're also interested in growing as much food as we can, both for health and financial reasons. After reading some books by Eliot Coleman on four season gardening in colder climates like Maine, we decided we'd like to try that. Seeing the hoophouses on display at the Common Ground Country Fair each year was also inspiring. So with our tax return in hand, I did some research on hoophouses and found quite a variety of information.

In general there are a few main options when building a backyard hoophouse:

- Do I build it with plastic or metal hoops?
From what I read it's much simpler to use PVC plastic pipes to make the hoops because they're flexible enough to bend by hand and very cheap. The downside is that they're not very strong and apparently have a habit of degrading the plastic where they touch. Also, they'll eventually break before a metal hoop would. Metal is obviously stronger and will last longer, but it's more expensive and you need tools or jigs to bend it. The metal that is commonly used in small hoophouses is EMT conduit. I've seen designs using everything from 1/2" EMT conduit to 1 3/4" fence rail. EMT conduit is convenient because of it's cheap price, availability and it is galvanized. While you could use wood to build the frame, it seemed much more complicated to me.

- Do I make it semi-circular or a gable design?
Traditionally, hoophouses have been semi-circular in design. I think this has mostly to do with simplicity in construction. However, you may also lose a lot of headroom or vertical growing room on the sides depending how wide your hoophouse is. A gable design is much like a simple house, with straight sides and then a straight sloped roof to the peak. The benefit with the gable design is that you can have a much higher ceiling at the edge of the building for growing taller plants or simply for headroom. You can also set your roof pitch higher for snow in the winter. I decided on a gable design for the high headroom at the edge and because I'm planning to leave the plastic on all winter to experiment with some four season gardening.
With either design, I would need tools to bend the metal I'll be using. For hoops, there are hoop bending tools you can buy online or you can make a bending jig on a sheet of plywood. For my gable plan, I need discrete bends, so I'll be using a 3/4" EMT conduit bender. I'll need a 90 degree bend at the peak and 45 degree bends at the wall/roof edges. There is also a gothic style design, which is quite similar to the semi-circular design, but forms a sharper peak near the top.

- Do I buy a kit or make it myself?
Many businesses will sell you hoophouse kits, but I've found them costing much more than I want to spend on this project. I should probably mention right now that I'm very frugal and like to do things myself whenever possible, so from the very beginning I've been planning on doing most of the work myself. Shipping on the kits is also quite expensive and they're limited to specific sizes (often fairly small). Many of them don't even include a base frame or end wall framing materials. I found Eden House as a local business that sells and installs small hoophouses that actually look very nice, but they're still twice the price I'd want to pay.

Given all that information, my decision was to build a 12'x16' gable style hoophouse with 3/4" EMT conduit "hoops". The hoophouse will be taking up one corner of a garden, so based partially on that and our desires, we decided on the 12'x16' size. This was also determined somewhat by how wide we could make a greenhouse using no more than three 10' pieces of EMT per hoop. I wanted a 45 degree roof pitch, but didn't want the roof peak to be too high, so we decided on 4' side walls. With 8' of roof from the top of the sidewalls to the roof peak, that actually gave us a hoophouse width of 11.4' and a roof peak height of 9.7'

Now what about the base frame?
We didn't want to use pressure treated wood. Although relatively inexpensive, it's also full of horrible chemicals we don't want leaching into our soil. I priced out naturally rot resistant cedar, but it was quite pricey (a planed 2x6x10 was $24.55). So I went with some rough sawn hemlock 2x8 lumber from a local sawmill. I won't last as long as cedar, but it was much cheaper (a 2x8x16 was $11.10). The hoops will connect to the base frame with a couple conduit hangers on each side, basically u-shaped pieces of metal with tabs you screw in on each side. There will be a ridge purlin that will be 3/4" EMT and go the length of the ridge. At the top of the sidewalls there will be 1x3 boards going lengthwise acting as siderails to strenthen the building and attached to the hoops with the same strapping as on the base.

Constructing the hoops
The "hoops" in my case consist of a 4' sidewall, a 45 degree angle, 8' to the ridge peak, a 90 degree angle 8' down the other side, a 45 degree angle and a 4' sidewall. In all it should be 24' of conduit. The problem is that conduit comes in 10' lengths. D'oh! So how to connect the pieces together? There are EMT connectors available, but I tried both the set screw and compression type connectors and both were utterly flimsy for my needs. After some thinking and testing, I found out that 1/2' IMC conduit has an outside dimension that fits snugly inside 3/4" EMT conduit. IMC conduit is very similar to EMT, but has a thicker wall. So I tested cutting a 10" piece of 1/2" IMC and inserting 5" of it into one end of 3/4" EMT. Then I drilled a 1/4" hole all the way through both pipes about 3 inches from the end of the 3/4" EMT and inserted a 1/4-20 x 1 1/4" bolt through it, securing it with a lock washer and nut. Then I repeated the steps with another section of 3/4" EMT, so that the ends of the EMT were abutting. Once done, it made a very strong splice. One note, I found that not all pipes are the same sizes. For instance, when I tested 1/2" IMC from Lowes and Home Depot, it was just a fraction too big to fit inside 3/4" EMT, but the 1/2" IMC from my local True Value store worked flawlessly!

The EMT was bent using a 3/4" EMT conduit bending tool I bought at Home Depot. It's quite simple to use, but took a few trials to figure out where exactly to start the bend to get the lengths right on the resulting pipe. I used three 10' pieces of EMT per "hoop". Since the whole hoop was 24', I cut two of those pipes down to 7'. Starting from the ground of one side, I used a 7' pipe, bending 45 degrees at 4'. I did the same thing for the other sidewall. Then I bent the 10' piece at 90 degrees right in the middle. Connecting those three pieces gave me my hoop.

How will the plastic attach to the frame?
Wiggle wire! I learned about this while doing my research and it sounded like a great idea. Basically you install this metal channel along the edge of your frame, put your plastic in the channel and then insert this zig-zag tensioned piece of wire in the channel and that holds it in place. You can bend the channels over hoop circumferences, but I only have straight edges which makes it even easier. Then just screw the channel to the frame with some self-drilling metal screws.

Hoophouse materials and cost

Materials and Cost

Here is a Google spreadsheet where I've been tracking the materials and cost for the hoophouse. The spreadsheet might not show fully in this post, so you can also access it here

Spring Maintenance

It's spring and time to work on the bees!  At first glance in March, it looked like all four hives made it through the winter.  I did a quick check on the sugar candy one warm day and they all had some left.  After some discussion with Jeannine, we decided to move the bees for the summer.  They have been on the southeast side of our shed for years, but it makes it hard to mow and do other things in that area sometimes when the bees are really active.  So I moved them across the yard to a more isolated location.  I did it in mid-April one evening by securing the hives with ratcheting straps and carrying them the 100 or so feet across the yard.  I put some netting and brush in front of the hives in their new location so that any field bees would hopefully reorient themselves before heading out and I left a nuc with some drawn comb in the old location to catch any field bees that might return there.  For a couple days, I would empty any bees in the nuc into one of the hives.  Still looks like four hives were going at this point, but some were obviously stronger than others.  I also unwrapped them.

May 2 - With the slightly warmer weather, we decided to start feeding some 1:1 syrup.  We're using our half gallon quail waterers and an extra hive body on top.  They don't seem to be taking it down too fast yet.

May 4 - We really got into the hives today since it was a nice warm day.  Our hive names are currently A, B, C and D (from left to right).  The good news was that all the hives had bees.  The bad news is that hive D didn't have any eggs or brood and had a pretty small number of bees.  Hive A, B and C were all going great with lots of eggs, brood and capped cells.  So well in fact that we decided to use one frame from hive A and two from hive B to try to jump start hive D.  The frames we took had a lot of eggs, brood and capped cells (along with a lot of nurse bees), but it looked like A and B could spare the frames.  We're hoping hive D will be able to raise a queen from one of the eggs in the frames we added.  We're not in a hurry, so it doesn't matter that it will take a while and D still had plenty of honey and pollen to keep it going.  We reversed hive bodies on C and D, but A and B both had brood split across the two deeps, so those didn't get reversed.  I happened to accidentally find the unmarked queen in B and was able to mark her.  One other thing that we noted was the large amount of mold present on some of the frames.  I noticed it most in hive D, but other hives had some to a smaller degree.

With the rate A, B and C are going, I wouldn't be surprised if we got some swarms soon.  We need to move our swarm trap from the shed to a tree closer to the new hive location.  We also need to prepare some new frames with foundation to rotate out some of our old comb (and maybe some of that moldy comb if it doesn't get cleaned up).