I am just about to build a 18x48 pvc hoop house. Mostly, I plan on copying jrslick's design, which is linked below. My changes would be to add an extra purlin down each side and make all of the posts 4x4's set in concrete. I will also make the end hoops out of synthetic decking lumber.

Here is a link that might be useful: greenhouse thread

So at the end you wont have a hoop at all, but instead the wood frame and at the composite? I like that idea. My end walls will take the brunt of the wind And I think I will sandwich the plastic between cheap plastic fencing mesh.

20 to 25 feet wide is pushing the limits of 1 inch pvc, maybe a larger diameter would be better.

I have 3, 1inch diameter PVC and wood high tunnels. They are 18 by 45. Could have went longer, but that is all the space I had for them.

We have had up to 14 inches of snow on top of the high tunnels. The trick to this and for the wind is to have 2 by 4 beams with 2 by 4 "Leg". This will help hold your structure.

The middle beam is permanent. The outside ones were meant to be temporary, but I have never taken them down.

{{gwi:117214}}

Some more pics

{{gwi:287185}}

{{gwi:9882}}

I have also attached a link to several of my presentations and others that give plans on how to build one like this.
Good Luck!

Here is a link that might be useful: Homebuilt High Tunnels

Awesome Jay,
I don't mind going heavier with the PVC Pipe. Why have straight sidewalls? Mine would be opened almost every day. So I could easily work from the outside. What works better for a roll-up mechanism, Rounded or Flat walls. Rounded look way easier from a construction point of view.

Going to have to run off to the market soon. Thanks for the tips. I'll check out the other links soon.

You all take care.

In my opinion, you need some sort of sidewall to help with ventilation and air flow. If you don't have a sidewall, you will have to attach a wood hipboard, 4-5 feet up so you can vent. Either way will work, but the PVC will shear off without something to help support it. My friend made his out of PVC over galvanized ground posts. In a bad storm, the pvc pipe sheared off. In my set up, the 4 by 4 and 2 by 4 takes a brunt of the wind.

Jay

One thing people might want to know if they don't, PVC can be heated bent and cooled and it will hold it's new shape. I used to do this for conduit in electrical work. So for instance, the bends on the top of the side wall could be made with heat and a jig to put the bent conduit in until it cools.

I agree that it's a good idea to reinforce the side wall either way, Jay. I like what you have done....looks stout.

Why not drop ends of the pvc hoops straight in the ground instead of driving a sleeve first? That's what I am thinking about now. I'd auger a 6" hole for each hoop end put the hoops in, bolt them to the baseboard to hold them in the right position and back fill with concrete?

I am planning a scrounge around low tunnel that I can fit under with my garden scoot. I am definitely not handy! Can't even construct a sentence.

We don't need no good sentences around here, we need more vegetables! Good luck with your tunnel, Minnie!

I'm thinking 1.5" pvc for the hoops, hopefully that won't be too hard to bend. I don't know if I want 2" pipe for the ground stakes, and then telescope and glue or bolt the 1.5" into that. Or I could just use 1.5", drive a 3' piece 2' into the ground and cement a connector on top. It would be great to be able to stick a 6' piece 2' into the ground and not have to use couplings, but I think the pipe would be too long to hit with a hammer and drive into the ground.

I thought about using the gray pvc conduit, which is supposed to be better at taking UV rays, but I think I'll just paint the pipes with some white latex to help block the sun. I may use conduit for the two side purlins. The center purlin will be two 2x4's attached to ground posts.

My plan is to set nineteen 4x4 posts, five on each end, three down each side, and three in the middle. That's a lot of posts for a 18x48 structure, but at least I won't blow away.

How tall do you guys make these medium width PVC tunnels? They are usually 12' in kits.

I've got some white 2" pvc in 20' lengths in the driveway now. It's for the gravity irrigation project, I'll glue two together and do a trial run on arcs with a 20' base and a 25" base. I think it will do it. Back in a few.

Jay - how do you support and tie down your movable house?

[IMG]http://i1066.photobucket.com/albums/u408/Rustico_2009/IMG_0132.jpg[/IMG]

Maybe a picture will show up of the 20' wide hoop made from 2" pvc. I am sure 1.5" could bend to a much tighter radius.

This was a 40' length of pvc with 2 foot on each side reserved for direct burial.

Picture?

how will you anchor the ends of the pvc hoops to the ground?

I am thinking of setting the baseboards first with metal stakes I have left over from construction. Then setting the conduit in a holes and strapping it to the baseboards with conduit straps. Then, after the structure is built purlins,endwalls and all, back, filling the holes with cement. I may straighten the legs by heating and bending them to get a straight wall first.

Might be a bad idea...but for sure I can not drive any tube two feet into my native soil without destroying it. PVC won't go in more than 4".

I am still looking for a second hand metal hoop house too.

How about using some straight sections of PVC in the sidewalls and a 45* connector at the top to start the bend? One of the slideshows Jay linked to shows that. I'm sure if you clamp to the sidewall just above and below the connector it will stand up to wind.

Thanks ajsmama, that's a good idea. I will probably heat the pipe and bend it instead of using any connectors. It would be stronger. The round shape there on the driveway is not bad. I laid on the concrete with my feet where the dirt would be and could "stand" very close to the walls. Straight walls would be better for tables or for using hoops inside of hoops.

Oh, you talking about straightening them so I thought you wanted a straight sidewall. That adds height too.

I'm still figuring out how I want to build mine, with the galvanized hoops I have. A 2-3ft sidewall would allow me to have peppers and lower crops on the sides and more room for indeterminate tomatoes in the middle. Plus I'm thinking of attaching gutters to the hipboards and putting a couple of rainbarrels on?

i don't think 4" into the ground will provide much wind resistance. you mentioned that it would have to be wind resistant. can you use a post hole digger to make holes?
i have an auger that i can attach to my drill to make about 2" diameter holes in the ground. would that work? it goes about 20" into the ground. when you hit a rock it twists your arms violently.

I have had these discussion many times, with many people. The best way to secure this structure to the ground will be driving a metal pipe into the ground, several feet, and slide the PVC over the metal pipe. Then, run a bolt through the PVC, Metal pipe and wood baseboard. Don't concrete in the PVC, it will break and you will be digging out a hunk of concrete. That is if you want to make a Arch, If you want to make a Gothic shaped, like mine, then do what I shared.

About heating and bending, DON'T, it will become a stress point and it will break. PVC is fairly strong stuff, but it has it's limits. If it does break, the bend will shoot right through your plastic and you will be taping it up. If you don't believe me, heat and bend it. Set it up and secure it to the ground. Then start pushing and pulling on it to mimic the wind. These PVC buildings can move 2-3 feet in severe weather. See if it breaks.

I have looked at hundreds of plans for PVC high tunnels. I have spoke with and to hundreds of people too. The design I showed, the one AJ's is referencing, is the best design I have come up with. I know that there are over 10 of these structures build, I have seen most of them, and I am betting countless ones that I don't know about after sharing on Gardenweb, the Farm Show Magazine, Great Plains Grower Conference and multiple other smaller high tunnel workshops and meetings. Not to mention the letters, phone calls and emails I get.

I have had these PVC structures for 5 or 6 years. Just my thoughts, proceed as you see fit.

Jay

Jay - how do you anchor your movable hoophouse?

Randy, I don't want to put the pvc in 4" that's how far I can drive it and why I mentioned using a post hole digger.The 2" auger is probably a better idea.

Jay, I think you are probably right, about metal stakes being better. Not sure, if the base board can't move and the purlins can't move the pipe can't move.

Not sure I agree with problems in bending the pvc. except that it may be more complicated than it is worth. Connectors make a weak too.

I certainly don't find a structure that moves 2 feet acceptable and can't imagine building one out of pvc and wood, or anything else, that does. What part of your structures move two feet? Seems to me like the plastic sheathing wouldn't last too long with the frame whipping around?

I just did a price check.

17 sets of galvanized steel arches & legs for a 20' wide house frame are $1,175. 24' is $1,345. Baseboard bolts and one metal purlin with u-bolts included. That's really not that bad since they are local(no shipping). Something to think about.

We used a post driver over our 'top-rail' for chain-link fence, then cut off what was damaged. Worked well in our ground.

i made a hoophouse using the johnnies high tunnel bender. however it is for a 12' house. lostcreek.com has benders for other sizes. i used 1 3/8" chain link fence top rails that i bought at lowes and brought home in my pickup (no shipping). i think a 20' house would take 3 10' rails. that's $30 in materials per bow. you would also need a ridge purlin. i used more of the same material and bought cross connectors from jaderloon.com. for ground posts i used 1 5/8" chain link fence ground posts also from lowes. they come in 6' lengths. i cut them in half and drove them in about 2' and stuck the ends of the bows into the ground posts. then fastened as jay describes.
the house is 100' long. the corner posts are in concrete as are the middle posts. i also used corkscrew anchors on some of the posts. it gets very windy here.
roll up sides and additional purlins are just additional options. for endwalls i attached 2x4's to the end bow using pipe clamps and an endwall framing bracket that attaches to a pipe clamp on the end bow. for the 12' wide house i just needed 2 2x4's per end and they double as the door frame.
i'll go take some pics and maybe you can use some of these elements in your house.

Rustico- the PVC bows in the buildings that I have built were pushed down 2 feet when we had a severe thunderstorm roll through. It was packing 60-70 mph winds. Lost a few branches and shingles too.

About the bending, it is hard to get exact bend every time ( with practice you can). Also, it can deform the pipe some. When I started this building these, I wanted to do the same. My father in law is an electrician and has bend many a pvc pipe. He showed me how to do it, but then suggested against it.

Connectors are bad, but it depends on how you use them. If you are using a connector to connect two pieces of 10 foot pipe to make a 20 foot pipe, bad. Pipe with Bell housing at one end is much better.

If you use any of the 4 way or 3 way connectors to join pipe, that to will break. Don't waste your time. I use connectors to make the connection between the bow and the sidewall. Then I put a piece of strapping over it and screw each side down. That holds it in place. Believe it or not, they are not glued. That way if anything breaks, I can just replace the broken piece. Occasionally, I have a bow pop off the upright piece, but loosen the screws and I can put it right back on. In this pic, I used screws with washers. Now I use 3/4 inch industrial lag screws. They have a big head on them and it cuts out the need for washers. I am much happier with them and haven't had a problem.

{{gwi:289452}}

I have also added some additional strenghth by adding a 20 foot 1 3/8 chainlink top rail every 4 bows. I connect this pipe to the wood and then the up piece by a bent 1 1/2 inch EMT conduit. You can bend these at home with a conduit bender. Then I run a long bolt through the 2 by 4 and the EMT. It works really nice.

Another pic, not a perfect bend, but good enough.
{{gwi:310797}}

If you want to just make a metal framed one, here is a very economical way to go to bend your own. I have a low tunnel bender and it works great.

Jay

Here is a link that might be useful: Lost Creek Hoop Benders

Aj's-

My movable buildings are completely different, they are metal framed. I bent the bows from one 26 foot long pipe. They are 16 feet wide and 32 long. This is an early picture. We just got them covered with plastic and the ground isn't even tilled. We also only have one set of rails up in this picture. There are now 3 spots we can move them too.

{{gwi:9883}}

They are anchored to the ground by the rails that they ride on. The bows are bolted to a 2 by 6 and the 2 by 6 has solid 7/8 inch steel rod that is drilled through the 2 by 6 and rides on top of another 2 by 6 that is lag bolted to 4 by 4 posts that are buried 4 feet in the ground. Then the 2 2 by 6's are bolted together with 6 bolts on each side.

This picture includes a steel pipe roller, which I took off and haven't used since the first time I moved them.

Hope that answers your question.

Jay

Thanks Randy & Jay,

I'd like to see how you finished off your tunnel if you have the time, Randy.

I did look at the lost creek bender it is very affordable. For just one tunnel, the savings/trouble for the 24'wide hoop might not be great compared to the kit. The side posts that come on the kit are long enough to go into the ground, so that saves on some material and labor. I checked the price on top rail stock and when all is said and done, a homemade steel hoop and piece of pipe to drive on each side is about $50 and the hoop kit is about $79 for the same thing, not subtracting the value of the purlin and hardware from the kit.

After buying the cheapest bender which needs a few other supplies to set up, and replacing the purlin and hardware from the kit, the difference is only around $300-$400 not to mention the substantial additional time and labor. Worth it on several tunnels but maybe not for just one?

The post driver is a good idea,Marla. Around here, for that holes would have to be drilled first, like Randy mentioned.

here are some pics.

the house is 12x100









you can see the wiggle wire holding the film from both the endwall and the sides. the t-tape piece is for anti-billowing.






more wiggle wire






roll-up sides. endwall plastic buried in trench.






another view of wiggle wire holding sides and endwall film.






bow attached to hip board






bow attached to ground post and baseboard attached to ground post.the additional pipe clamp with the duct tape is attached to a ground anchor






linking 2 baseboards






2x4 door posts. 2' deep holes with concrete. a couple of nails at the end of the 2x4 in the crete






2x4 bracket, pipe clamp, holding the 2x4. this one is installed backwards...senior moment. the front edge of the 2x4 should be about even with the end bow






this is the ridge where 2 pieces of swaged tubing come together






cross connector holding ridge to bow






linking 2 pieces of hip board






strawberries

My metal hoophouse is a Clearspan kit from Farm-Tek. It's 14' wide. Each hoop is four pieces of Gatorshield tubing that slip and bolt together. I used chain link top rail as the pipe for the roll-up sides. Looking at the two materials side-by-side, the top rail is flimsy compared to the Gatorshield tubing, which is 1.3" I think. The reason that the kits seem so expensive in comparison to top rail is that they simply contain a lot of metal. It's thick, sturdy stuff. The metal pipe itself is expensive before it even gets put in a bender.

The problem with hand-bending metal is that anything that is small enough for you to bend by hand is not very strong in a structural sense. If I bought a bender right now, I'd buy a hydraulic one for about $500 and try to copy Clearspan's design, with short pieces of fairly thick galvanized pipe. If I had money out the wazoo, I'd buy the $15,000 'rolling bender' that allows you to bend one single piece of pipe over a long arch.

Great pix randy - what is that mesh on the inside of the plastic? Looks like you take plastic off over the summer?

Nice job, Randy. Thank you. That's a lot of useable space and nice structure. Is that decomposed granite soil? All the rocks scattered around look familiar, Maybe something else?

Back to the pvc for a minute. How long will it last painted?

If it can last 10 years or more that would be great.

Jay, would a brace between the two purlins at each set of posts help with the flexing? Seems like it would? You could even put a support from the cross brace to the center purlin, more or less like a truss. I did a farm visit this weekend and the 30' hoop house had a cross brace in there every 4th hoop or so, but nothing going up from it to the center purlin This was a metal hoop structure and probably didn't need the second part. Nice hoop house and the man said he had the plastic on since 2003. It still looked brand new.

the house was used to grow melons over the summer without the film. the netting kept the deer and crows out.
i have a hoophouse built with even thinner conduit than the one in the pictures. i've had it for over 20 years and it has held up fine even after being set up and taken down and moved several times. this is possibly a cheap alternative to using pvc. pvc is supposed to react unfavorably with poly film causing the poly to break down prematurely. i have no experience with that.
there's more pictures of hoophouses and a high tunnel on my farm's facebook page. if you are interested in checking it out search for indian valley farms. the 26x48 high tunnel that there are pictures of has trusses and a lot of bracing. it was a kit i purchased from rimol greenhouses. i have a second hand hoophouse frame that was 14x72 that blew down. many of the pieces got bent and it became a 14x32 house. my homeowners insurance claim generated enough money to buy the rimol kit.
at this point we have 4 tunnels totaling about 3300 sq ft of growing space. i have the bows to build a 22x48 high tunnel also. rimol shipped the wrong size bows when i got the 26x48 kit and never took them back.

we do have a lot of rocks here. the soil that the strawberries are in under the plastic mulch is well composted and bigger rocks removed.

I love the idea of the netting but what I should have asked, is where do you buy a piece that big? And how do you attach it?

Yes, I've been told PVC (even UV-resistant) will cause the poly to break down, so paint the parts that come into contact with latex paint. That's what my neighbor did. He's got a small hoophouse - maybe they'll let me take pix of it. He built solid endwalls, it's not quite as temporary as what we've been talking about.

Jay - how do you move you house? Both end walls look like plastic, I thought you'd hook up a tractor and drag it but don't see where to hitch it, and if it's sturdy enough to drag? Or do you take plastic off, unbolt it from the ground anchors, and then drag it from both sides one end (without it racking)?

I attached my shade cloth with clothes line anchored with concrete blocks, some partially filled. Where the graoments were out, I used a tarp strap accessory, like a big clothes pin, but with teeth. Check with Farm Tek, they have about everything.

farmtek is where i got the netting. held on with plastic cable ties.

Thanks - that looks like a great alternative to the thin (cheap, ripping, small sections) bird netting I've been using over my berries and even the sturdier stuff I've been using as deer fencing around the house garden (need at least 7x100ft roll).

If it's UV resistant, I can even see using that over the poly to prevent billowing.

Is this it?

Here is a link that might be useful: Game Bird Netting

you will have billowing no matter what you do. It's natural, even my house billows. It allows some room for expansion when it gets hot. You don't want the house to be 'air-tight'.

I'm leaving my shade cloth on this winter. I have cats that have been climbing all over it and I think the shade cloth will get the film some protection from ripping.

The endwalls come up the bottom 2.5 feet and can travel over the inside crops or go over the new crop, as in carrots. Here is a video of moving it. My brother in law is on the other side and they slide right down the track with minimal effort (minimal for me). I have now gotten to point that I move them myself. I just pull it up myself. I just yank one side 2 to 3 feet and then walk over and do the same thing to the other side and just walk it up or down the rails. It takes me about 30 minutes to unbolt, move one space and rebolt it in its new home. It takes about 20 minutes if I have two people.

Some people show how they can move their high tunnel, much bigger with just 2 people. Those systems are extremely high priced and in my mind aren't worth the expense. Why spend $1,000's of dollars in tracks and wheels to move it "Easier" 3 or 4 times a year.

About the plastic and PVC interaction, I haven't seen it. I have replaced my plastic after 4 years due to seam failures, not plastic/PVC interactions. I have never painted them either.

I am thinking I will get 8 to 10 years out of it, or more. However, my first tunnel, I did a minor replacement of the soft 2 by 4's after 4 years. The funny thing is the 2 by 4 hip boards were in worse shape than the baseboards. Both were untreated pine.

Jay

Here is a link that might be useful: Moving our movable high tunnel

Thanks Jay - I don't want to hijack any more of rustico's thread, so I'm going to update my high tunnel thread - I'd like to get your thoughts (anyone else's too!).

the netting is the lightweight stuff.

Don't worry about hijacking anything I start, ajsmama, we have the same interest/goals.

You have a beautiful place Randy, thanks for sharing that. Good job on all the hoop houses!

Thanks for the comments on durability of the parts, Jay.

It looks like I can ask for some roll up gear boxes for X-mas!
Does anyone know if the kits can be used with strait or curved sides? Which ones would you recommend? The set on the Rimol site looks good. One pair goes to 60' and one set for is for a tunnel 72'-96' long. I will be using the gear boxes very often, so they should probably be some of the best on the market.

I have a smaller area in which I would like to build a hoophouse. It will be located next to my garage and it can not be larger than 8' wide.

Any thoughts on PVC frame design?

Thanks

Rich, first thing, check how much wind you get at the location that you want it. I tried a lean-to PVC, but the wind was too strong. I finally decided on the metal carport, screwed together, with wooden baseboard and door framing, then covered with greenhouse film. 4-5 years and still working, except need to replace wooden screendoor, about $19-20. Worked great snugged up to white metal mobile southern side.

I didn't anchor it to the ground either, and it hasn't moved, even with 60 mph winds.

I used this until I got the bigger greenhouse. Still use it for storage and overflow.

I don't think 8' is wide enough to have a typical quonset hoophouse that is tall enough for most people to walk through. You would need vertical sides of some sort.

I looked into pvc but ended up going with top rail. Between chain link fence material and metal conduit, there are a lot of other options that are stronger than pvc.

Yeah, I also figured 8' would be too narrow for true hoop.
I can build up the sides a couple feet with 2 x 4's and start the hoop at that point.

As for wind, it would be in a pretty sheltered area with houses blocking the prevailing westerly winds.

Thanks for the replies..

Rich