high tunnel plans
 

Currently have a 16 ft x 8 ft raised bed made from railroad ties.

My plan this spring is to expand it another 8 ft, for a total of 24' then enclose it with 16 ft long cattle panels to create a high tunnel. 16 ft panel across an 8 ft. space works out to a max of 5.8 ft of head clearance.

The far (back) side will have a 30"x60" screen, the front door is 36"x61".
The ridge pole spans are 12', supported in the middle by a 4x4 post.

The tall circular plants represent tomatoes, they are spaced 30" apart on-center.

My main concerns are:
-heat; in Nebr. it gets HOT, often in mid-90's

-irrigation; current raised beds are ditch irrigated. The bed slopes from right-to-left which won't work given this design (it would flow across walkway).


when/if construction begins, I'll keep this thread updated.

[IMG]http://jess-dan.com/pictures/greenhouse/greenhouse_view2.jpg[/IMG]

if you can add 2 bars on the top of the sidewalls and attach your roof plastic to that, then you can have walls that could be raised in hot weather to vent the greenhouse. you can use a net fabric for the walls at that time and you can add some shading if it is still too hot. That would be similar to a chapel design greenhouse, mine is like that, because i have 4 seasons, and without the flexible walls and the rigid roof i would either cook the plants from the heat or have the wind blow it away

I would be worried about the rough edges of the cattle panels rubbing against my plastic as it flaps in the wind.

For venting, the cheap way to go is sides that roll up, or at least have plastic that can be clipped up to make a side vent.

Any worries about the RR ties and chemicals affecting your plants?

Are you going to try to bend the cow panels?
Worth

@GreenFarmer
1st pic below is a design that has 4x4 poles just inside the RR ties; 2x6's attached to the 4x4's. The cattle panels still go over the 2x6's and get attached to both the 2x6 and RR ties. I actually like this design better, I think it will help to firm up the entire structure. Wind here is relentless.

Plastic would get attached to the 2x6 "knee wall" leaving a "flap" of plastic that runs down to the RR ties. The extra flap could be opened for ventilation.

This what you were talking about?



@Whoose
The RR ties I used were recycled and not brand-new so there wasn't much sticky creosote left. My first 2 yrs of gardening in the raised bed it hasn't been a problem.

@Worth1
Yes, I've watched quite a few youtube vids, and it seems pretty easy to bend them into an arch after 1 end is attached. Given my 24' span, I plan on a ridge pole and support beam at 12'.

[IMG]http://jess-dan.com/pictures/greenhouse/greenhouse_take2.jpg[/IMG]



[IMG]http://jess-dan.com/pictures/greenhouse/greenhouse_take2_vents.jpg[/IMG]

You know those bamboo curtains they have?

You could do the same thing with a long joint of PVC pipe attach the bottom of the plastic to the bottom all they way down.
You would be able to roll the whole side up at once.
1 1/2 half would work great.
The ends of the pipe could stick out more on each end and you would be able to hook then where you wanted.
Put a cap on the ends to keep the wasps from building nests in them.

Worth

I have built 3 of the cattle panel greenhouses over the past few years.

I do not have as much wind as you, so I haven't needed to use a center purlin reinforcement. I just bent over the cattle panels and secured to the wood baseboards. For some reinforcement, I overlapped each cattle panel about 3 inches and secured with zip ties.

To cole_robbies point, secure the plastic as tight as possible. Also, make sure the smoother side of the panels are facing outward (for less damage to the plastic).

I have found the limited height to be a challenge. With the apex at 5 foot 8 inches, I have gashed my head a few times when walking through. I ended up raising my entire tunnel a few inches by adding a second set of wood base supports (the railroad ties in your case) on top of the first set. I made the top row a little narrower than the bottom row so that the bottom of the panels would sit on top of the bottom row and push into the side of the top row. (A picture would serve better, I'll see if I can find one.)

The other question about height is that if 5'8 is the apex, then your plants cannot get very tall before they 'hit the ceiling'. Not sure what your plans are for growing. I use my houses for growing shorter varieties and dwarfs.

I combat the heat by using shade cloth and/or running cheap fans on a timer.

Good luck.

Bill

[QUOTE=natural;519269]I have built 3 of the cattle panel greenhouses over the past few years.

I do not have as much wind as you, so I haven't needed to use a center purlin reinforcement. I just bent over the cattle panels and secured to the wood baseboards. For some reinforcement, I overlapped each cattle panel about 3 inches and secured with zip ties.

To cole_robbies point, secure the plastic as tight as possible. Also, make sure the smoother side of the panels are facing outward (for less damage to the plastic).

I have found the limited height to be a challenge. With the apex at 5 foot 8 inches, I have gashed my head a few times when walking through. I ended up raising my entire tunnel a few inches by adding a second set of wood base supports (the railroad ties in your case) on top of the first set. I made the top row a little narrower than the bottom row so that the bottom of the panels would sit on top of the bottom row and push into the side of the top row. (A picture would serve better, I'll see if I can find one.)

The other question about height is that if 5'8 is the apex, then your plants cannot get very tall before they 'hit the ceiling'. Not sure what your plans are for growing. I use my houses for growing shorter varieties and dwarfs.

I combat the heat by using shade cloth and/or running cheap fans on a timer.

Good luck.

Bill[/QUOTE]

thanks for the great advice! To gain some headroom, I could always attach the bottom of the panels a bit higher so they are not resting on the RR ties. It would be easy to attach a 2nd horizontal 2x6 that rests atop the RR tie.

I'd have to re-run the model with the edit, but I would gain about 6" of headroom, up to about 6 ft.

Probably just grow determinate toms, there are tons of varieties out there.

Just build some side walls to raise everything up. If you orient the structure east-west, your north wall need not be clear. If you build a 4-6' tall wall in the back and a 1-2' wall on the south side, you would add a lot of head room.

[QUOTE=Cole_Robbie;519273]Just build some side walls to raise everything up. If you orient the structure east-west, your north wall need not be clear. If you build a 4-6' tall wall in the back and a 1-2' wall on the south side, you would add a lot of head room.[/QUOTE]


Yep, current 16'x8' bed is running East/West. I'll revise drawing and re-post later.

i think that the 2x6 "knee wall" that can be opened is similar to what i am tlking about, only, my walls are about 7ft high that i can walk in when they are open. in the middle of the house at the highest point of the arch, it is about 8.5 ft, and i find that to be limiting. a great idea is to spray white lime stuff used in construction in mid summer, a cheap effective way for shading, and cleans off alone when it's rainy and cold

version 3 below.

-4x4 post around inside perimeter of RR ties are now 24" above the soil surface.

-Horizontal 2x6 are set down 1.5" from top of 4x4 posts

-Bend cattle panels sit on top of the horizontal 2x6

-Comes out to 7.4 ft of head clearance

-changed the ridge pole to be 2x6, span is still 12 ft

-changed header above each end door to be 4x4

Questions:
1. how should I anchor the 2 ft 4x4 posts around the perimeter?
[URL="http://www.menards.com/main/building-materials/fencing/fencing-accessories/oz-post-t4-850-3-1-2-square-post-anchor/p-1444450508344-c-5764.htm?tid=-1701248779416275060"]Anchors[/URL] or traditional sonotube/concrete footings with 4x4 bracket on top?

2. I have a 6ft 4x4 on the inside of each end door, just as something to fasten the vertical door jam to. Any other recomendations on how to support the vertical 2x4's on the ends?

My thought is that keeping the hoop house support on the inside of the RR ties and independent from the RR ties, will allow for easy replacement of them when they rot out. I.e. not having to lug them inside the hoop house, or unfasten any major structural components.

I struggle bridging 3D design to reality, much more experience with the former.

thanks.


[IMG]http://jess-dan.com/pictures/greenhouse/greenhouse_take3.jpg[/IMG]

I made my hoop house 6.5 feet high and I am re-doing it now because it is annoying to have to crouch near the sides. I am now making it 8.5 feet which will allow me to put my plants all the way against the sides without the curve of the hoops interfering or having to crouch. My advice, if you can make it taller w/o much trouble, do it. I dont get much bad weather here but I made mine strong enough to make it through anything. I need to take some pics and post a little how to guide but time is short and many other things to do.

In short the first and last hoop are 1 inch PVC for the rest I used 20ft sections of rebar covered with black plastic water pipe as my hoops. Drove 5ft sections of 1' conduit 2 ft into the ground leaving 3ft for a hip board to attach to. The conduit was secured further at my base 2x6's with metal U-clamps. The hoops slide 12 inches into the conduit. I used 1/2 inch conduit as ridge poles and also 3ft down from center on each side, secured with metal hose clamps and zip ties. I had to make the first and last hoop PVC so I would have something to attach the end walls to.

After doing all this i think i probably should have just used 1 inch PVC for the whole thing but hindsight is 20/20. Good luck!

One thing you can think about is to make the thing with Gothic arches.
Much more practical than the Gomer Pyle USMC quonset hut.


Worth

I decided to go with Johnnyseed's Gothic Arch Bender. I drafted a "wall section" plan and will be applying for building permit tomorrow. According to city building and zoning folks, I'm cleared for a greenhouse on my lot as long as it for personal, not commercial use. I'm going to be ★★★★ed if there is a snafu in getting the permit, I just placed a Johnnyseeds order!

32' Long X 14' Wide X ~9.5' Tall at center
double layer clear 6 mil poly film. Johnnyseeds spacer blocks between layers
Roll-up sides
End walls will be identical; treated 2x4, covered with clear rigid roofing panel (home depot)
I'll get used storm doors on craigslist

[IMG]http://jess-dan.com/pictures/greenhouse/detail_lg.jpg[/IMG]


[IMG]http://jess-dan.com/pictures/greenhouse/detail_endwall.jpg[/IMG]


[IMG]http://jess-dan.com/pictures/greenhouse/jsorder_Page_1.jpg[/IMG]

Neat. That's exciting.

For what it's worth, you really only need concrete on the corner posts, unless your soil is very sandy with no clay. 2x4s should be fine for the hip boards, instead of 2x6s. And for the plastic below the hip board, you want a single layer, because you can't inflate the part that rolls up, at least as far as I know. I doubled the plastic in that section and mine turned cloudy from rubbing together. A single layer would have been better.

Your two end purlins take the brunt of the wind. When a greenhouse collapses from wind, the end purlins twist, and then it all falls in. If you want to strengthen your structure, extra bracing for the each end rafter is the first place to start.

[QUOTE=Cole_Robbie;531607]Neat. That's exciting.

For what it's worth, you really only need concrete on the corner posts, unless your soil is very sandy with no clay. 2x4s should be fine for the hip boards, instead of 2x6s. And for the plastic below the hip board, you want a single layer, because you can't inflate the part that rolls up, at least as far as I know. I doubled the plastic in that section and mine turned cloudy from rubbing together. A single layer would have been better.

Your two end purlins take the brunt of the wind. When a greenhouse collapses from wind, the end purlins twist, and then it all falls in. If you want to strengthen your structure, extra bracing for the each end rafter is the first place to start.[/QUOTE]

my soil is 100% gumbo heavy clay. I think I'll take your advice and only concrete the corner posts. Still 8" of snow on the ground, so I have some time to think...like I need to do more of that!

That's a beauty!

Another thing I would like to add.
If you are going to sink pipe up into concrete footings make sure the concrete is above grade.
Also it will last almost forever if you wrap it in underground pipe wrap.
I would much rather use anchor plates on the bottom of the metal and bolt it to the concrete.
Do this by putting your J bolts in the concrete before it sets up.
Make a plywood pattern just exactly like the pattern of the support plate put your bolts and nuts one it and set it in the concrete so it doesn't move around or sink.

Worth

[QUOTE=Worth1;531615]Another thing I would like to add.
If you are going to sink pipe up into concrete footings make sure the concrete is above grade.
Also it will last almost forever if you wrap it in underground pipe wrap.
I would much rather use anchor plates on the bottom of the metal and bolt it to the concrete.
Do this by putting your J bolts in the concrete before it sets up.
Make a plywood pattern just exactly like the pattern of the support plate put your bolts and nuts one it and set it in the concrete so it doesn't move around or sink.

Worth[/QUOTE]

everything I've read says to have the top of the concrete slightly below grade when setting chain link fence posts; prevents frost heaving. In the above drawing, the concrete footer is 4" below grade. I will also put bolts through the posts prior to setting them in concrete to prevent them from pulling up after the concrete sets.

What do you figure you'll have in it, not counting your raised beds as they are already built? If you don't mind me asking?

[QUOTE=pecker88;531628]everything I've read says to have the top of the concrete slightly below grade when setting chain link fence posts; prevents frost heaving. In the above drawing, the concrete footer is 4" below grade. I will also put bolts through the posts prior to setting them in concrete to prevent them from pulling up after the concrete sets.[/QUOTE]


I was thinking more on the lines of a catastrophic event such as the collapse of the structure.
This way you could start over without having a bunch of pipe or what ever stuck in concrete you couldn't do anything with.

To prevent frost heave pour the footings down below the frost line.
Worth

You should try to build something on permafrost and see the mistakes people make.
The building heats up the permafrost and the whole thing sinks in the ground.:lol:

Worth

[QUOTE=PureHarvest;531632]What do you figure you'll have in it, not counting your raised beds as they are already built? If you don't mind me asking?[/QUOTE]

don't mind at all. My goal is to build a middle-of-the-line hoop house, not cheap, not elaborate.

I'm doubling my current raised bed area so I have roughly 1/2 the soil I need. The city gives away free compost in the spring, I'll go get a few pickup loads. I just found out about this program yesterday, seems too good to be true: [URL="https://lincoln.ne.gov/city/pworks/solid-waste/lingro.htm"]see here[/URL]

The above order from johnnyseeds was $812.85 including shipping. I'm waiting on the rest of the material until spring, and so my wife doesn't loose her cool.

Items remaining:
treated lumber for hip/base boards and end walls - $200
clear poly roofing panels for end walls - $80
hor/vert enclosure strips for corrugated roofing panels - $20
hardware - $50
storm doors - $50
double 6 mil poly covering, 40x75 ft - $380
10ft chainlink top rail - $350
8ft chainlink line posts - $150
chainlink fasteners misc. - $40
quality landscape fabric for under/around line posts - $125
parachute cord for lacing roll-up sides - $40

sub total: $1485
grand total: $2298

seems reasonable for a cathedral shape 32x14 structure with double poly, no blower.

[QUOTE=Worth1;531634]I was thinking more on the lines of a catastrophic event such as the collapse of the structure.
This way you could start over without having a bunch of pipe or what ever stuck in concrete you couldn't do anything with.

To prevent frost heave pour the footings down below the frost line.
Worth[/QUOTE]

I've thought about this, more-so when I was thinking about using 4x4 treated posts, (see earlier posts in this thread) as they would be easy to swap out when they rotted.

But several building forums mentioned that above-grade footers with anchors like you explained are for downward point loads, (houses, decks) and not so much for fences. The physics in my head seemed to justify their claim, but I'm by no means an expert.

[QUOTE=pecker88;531641]I've thought about this, more-so when I was thinking about using 4x4 treated posts, (see earlier posts in this thread) as they would be easy to swap out when they rotted.

But several building forums mentioned that above-grade footers with anchors like you explained are for downward point loads, (houses, decks) and not so much for fences. The physics in my head seemed to justify their claim, but I'm by no means an expert.[/QUOTE]

Here is the deal about footers for net and chain link fences you want to have them below ground for three reasons.
One the bottom of the fence is at ground level.
Two you dont see the ugly footers sticking up.
Three the soil wont wash away and leave the footing sticking above ground.
We dont have frost heave here where I live in Texas but we do have something else and that is in many places clay soil.
No one builds a house on clay soil here that is worth a hoot.
They may pour footers and the slab but they dont drop pilings below the line in the clay where it doesn't get dry and wet.
Now everyone has a house that moves around.
One way to stop this is to put in rain gutters and channel the water away that is what I did.
Another thing to do is to excavate out around the area of the house and put a layer of stabilized sand down on top of the clay before you pour the slab.
That slab needs to be on a vapor barrier.

Worth

Your roll-up sides will need something to roll around if you want them to roll neatly, typically top-rail. For my high tunnel, I just pull up the sides and clamp or bungie them to hold them up. It doesn't look as neat, but it works.

This stuff is great for attaching plastic to lumber for the end walls and doors:
[url]http://growerssolution.com/PROD/batten-tape/BTFS[/url]

[QUOTE=Cole_Robbie;531649]Your roll-up sides will need something to roll around if you want them to roll neatly, typically top-rail. For my high tunnel, I just pull up the sides and clamp or bungie them to hold them up. It doesn't look as neat, but it works.

This stuff is great for attaching plastic to lumber for the end walls and doors:
[URL]http://growerssolution.com/PROD/batten-tape/BTFS[/URL][/QUOTE]

Is it sticky too.
Were I put the soil back to where it belonged next to the house is where I want to put a shed green house made out of wood with a wood floor like a deck.

Worth

[QUOTE=Cole_Robbie;531649]Your roll-up sides will need something to roll around if you want them to roll neatly, typically top-rail. For my high tunnel, I just pull up the sides and clamp or bungie them to hold them up. It doesn't look as neat, but it works.

This stuff is great for attaching plastic to lumber for the end walls and doors:
[URL]http://growerssolution.com/PROD/batten-tape/BTFS[/URL][/QUOTE]

ugh, I forgot something else on my above list...;)
10ft sections of 3/4 EMT + fittings - $60

I'm following [URL="http://www.johnnyseeds.com/assets/information/7300-qh-stationary-gothic-high-tunnel-bender-instruction-manual.pdf"]JS's guide[/URL], almost exactly; they said to construct roll-ups with 3/4" EMT. I ordered a bunch of poly-channel & wire from JS's; that's how I'll attach poly to side walls.

For end-walls I'm going to build a 2x4 frame that roughly follows the arch, then attach the poly-channel to the 2x4's. The poly film gets ran over the end of the end-wall arch, and straight down to the poly-channel. Just below the poly-channel on the 2x4 I'll fasten the rigid clear roofing panels. Seems like a good way to "union" poly film and rigid poly roofing panels.

Example pic: note the poly-channel running along the 2x4 under the arch. Same idea.

[IMG]http://i587.photobucket.com/albums/ss315/jrslick/IMG_4404.jpg[/IMG]