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Building a hoop type greenhouse....

2K views 13 replies 6 participants last post by  A.T. Hagan 
#1 ·
I will soon be building a hoop type greenhouse....3/4" PVC pipe ribs, 6 mil Greenhouse film glazing. What is the best way to fasten the film to the ribs?
 
#2 ·
Ours is fastened to the 2 x 8 frame that forms the bottom of the walls, rather than to the ribs. There are a number of ways to fasten the poly film down:

Lath and double-headed nails -- roll the bottom around the lath and nail it down. The double heads make it easy to pull off to roll the sides up for ventilation. It gets kind of hard on the poly, and can pull out in steady stiff winds.

Channel lock -- one piece is permanently fastened to the wood, the poly is laid over the channel, and the locking piece is fastened over by pounding with a rubber hammer. Holds much better than lath & nails, but is more expensive and a bit of a pain to take off and put on continually for ventilation.

Wiggle wire -- much like channel lock, except the locking piece is a length of zigzag wire. It's "wiggled" into place with a back and forth motion, easy to do and undo. This is what is now on all our hoop houses.

What are you planning for the ends? We used clear fiberglass, but are in the process of replacing it with doublewalled acrylic. It doesn't burn or get yellow, both of which fiberglass does.

These are for walk-in houses; if you are doing more cold frame type structures, there are plastic clips that will hold poly film down onto poly ribs. We got them at a local hardware store. This spring, I'm going to experiment with twine tied from one rib bottom over the top to the next. Supposed to be able to push the sides up and down easily but still hold -- we'll see.
 
#3 ·
When i had my hoophouse in AZ, I fastened the sides to that light weight sewer pipe that is white on the outside and black on the inside. What I did was sawed a section in thirds and then used those pieces to clamp the plastic onto full pieces and screwed them together (wish i had pics) then drilled a 1 inch hole in each end and put a piece of pvc pipe through for a handle. My hoop house was 20 feet long and I could very easily roll up the side from one end by myself. It sealed along the ground well also. I'll try to find pics if I can.

ETA: Found a couple of pics. Ignore the large holes in the side of the pipe, this pipe was salvaged from a hydro project.





 
G
#5 ·
I'm using firring strips and screws to attach my plastic to the greenhouse frame (2x6s) and on the two end hoops I'm using pvc snap clamps.

http://www.groworganic.com/item_SER262_Rowcover_Snap_Clamps_34.html?pMode=HiRes
The graphics are from their website.

They hold the top cover plastic and end the end plastic in place and have done a pretty good job so far. If you're careful you can take them off and put them back on without tearing the plastic.

Are you going to insulate your greenhouse? How will you be heating it?

.....Alan.
 
G
#7 ·
No clips on the interior ribs. The photo you have above is very much like my house this year. The clips are only on the end ribs. No need to use them on the interior ones. The tension on the plastic being secured along the sides holds it in place just fine.

In North Florida I can get away with a single sheet of plastic and a heater, but I'm not sure if you're going to be able to do that in Missouri unless you've got a very favorable set up. Heat loss through the plastic is high so on the nights it really goes below freezing you may not be able to pump the heat out fast enough. Of course if it's something small like an 8x10 house you might be able to do that. One of the clear plastic insulated pool covers might help a lot in that regard.

There's a greenhouse forum over to the GardenWeb that you might find helpful.

.....Alan.
 
#8 ·
Of course if it's something small like an 8x10 house you might be able to do that. One of the clear plastic insulated pool covers might help a lot in that regard.
Right now I am looking at 12'W x 14' L, about 7' something in the middle. After some thought, I have a 20' by 40' blue plastic tarp I could double and cover most or all of the greenhouse at night(or really bad day), and roll it back during the day. Wadda'Ya think??
 
G
#9 ·
Can't say for sure about the blue, but I suspect it may not let enough light in. 12x14 is big enough that I'd carefully investigate your heating needs before I risked a lot of plants I didn't want to lose on a really cold night.

I haven't bought one yet for my own greenhouse so I don't want to say too much about them though I intend to have one for next winter.

GardenWeb Greenhouse Forum
http://forums2.gardenweb.com/forums/strucs/

Check those folks out. Lots of hands-on applied knowledge there.

.....Alan.
 
#10 ·
I have a little one I made with wood about 7 by 7 I put 300 plus tomatoe plants in it started in doors on mar 1st Put them in the green house april 1st and only had to heat two nights with a cheap electric heater from walmart and it was on low. The plants were huge and had maters on the when I set them out may 10th. I am planning a better insulated one and much larger first I am building 3 more hoop houses 11 by 32. I have used clamps in the past it looks like I may need to try the pipe holders like mr hagan uses. Incidentally I am going to be reading your prudent pantry book next month. I am using furring strips to attach the sides to recycled 2 by 12's and the ends I have not figured out yet, Also I got some plastic flat rope type stuff to put across the plastic 300 feet for $20 or so.It will keep the plastic from blowing so much I hope.My sides on these will not be opened except for the summer I think I can regulate the temp enough from the ends for the spring.
 
G
#14 ·
Just keep in mind the bigger the structure the greater the heat loss which equates to the more heat you have to put in. Not so big a deal for me in North Florida where I nornally don't have weather going below 20. For you folks that have to deal with teens to single digits or lower it can matter a lot. If you haven't built one before then keep your first smallish unless you have good reason to know better. You'll know a lot better what you are going to need in your second season.

My first one was a little six by eight by about four feet high then went to an eight by ten by about six feet high for a couple of years. I'm up to a 12ft x 20ft x 7ft now. I can see I'm going to want to go to an insulated cover next year because I'm approaching the limit of the BTUs the 110 power I can run out there can deliver.

If you will be using electric heat then give some thought to what you will use for emergency backup heat if you lose grid power for a while.

....Alan.
 
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