I built one and it lasted until the edges of a tornado came through our area a few years ago.

Here is what I learned:

Use Schedule 80 PVC - it is heavier, grey (therefore more sun resistant). It can be purchased at most large discount stores, Lowes, Home Depot, etc.

It bends fine. My design used two 10 foot sections joined at the top spline.

I don't know about visqueen, but I used greenhouse film which can be purchased at lots of large GH or garden supply stores. I used regular heavy plastic film (from Lowes) the first season and by fall it was totally rotten. The Greenhouse film (I used Tuflite IV) will last up to 4 years.

I don't know what zone you are in, but it will not hold heat at night and supplementary heat must be used if you use it during very cold weather.

Good luck.

GD

Thanks. I just have a few more ends to cover:
You said that I need supplementary heat... what kind of unit can I use? And will it be hard to heat a hoophouse if it has big holes in the plastic (like near the ground), or is there a way I can make it near air-tight?

Mine had a 2x6 treated base that the pvc hoops were attached to. I just stapled the plastic all along the base as near the pipe as I could.

I only used mine beginning in mid-March and placed the seedlings on the bottom shelf and draped a plastic tent over the bench to the ground, placed an electric milk-house type heater on the shelf set it to come on at about 45. Of course, the minute the sun hits the house the next day, you have to remove the tent. Mine certainly was not automated in anyway. I started the seedlings in the house under lights.

another option for hoop houses is to put a concrete rebar inside the plastic pipe gives a lot of extra strength while protecting the plastic from rebar abrasion.

Hi I put a 16' by 20' up 6 years ago and it is still doing fine although now it is just used for storage and mixing of soil. You can go to the link below and then hoophouse construction of how I built mine.

Bob in North Alabama

I used the same Westside Gardener plan to build a 9 x 15' hoophouse last fall. I am still experimenting with the most effective way to make use of it. For me, the trick is to think of it as a very large row cover and not as a greenhouse, because I don't want to put the money into the necessary heating and ventilating, and in my climate, there's really no call for that.

What I have so far found it good for, here on the margin between zones 7 and 8:

Terrific lettuce and spinach all winter.
Beautiful carnations and nasturtiums, nasturtiums to Christmas and carnations all the way through.
Started and grew beets successfully, are maturing now outside.
Provided a good spot to keep my worm bins warm enough to stay active without going into the house, which I just don't want.
Nice place to sit on a sunny, cold winter day.
Nice place to do garden work when it's raining.

This spring I took down the plastic on the northwest end to mitigate the temperature extremes that are, for me, the main drawback to the cheap and simple design. Temps are still a few degrees higher than outside (2 to 10, depending on whether I open the other end or not.) I have a nursery bed for my tomatoes in there, and will give them extra cover if temps fall very far. I have also started peas and potatoes in beds and will remove the plastic probably in late April or early May. I'm hoping this will get the spring things mature before the temperatures get too hot and give me a good long spring harvest.

Good luck, best,
Martha

A few extras on the PVC. You would be wise to paint it or it will deterioriate the plastic where it touches. Schedule 80 PVC is about the same price as galvanized arches. If you are buying plastic from a greenhouse supply store you will appreciate also buying a wire-lock system to hold your plastic to the base and ends. It isn't that expensive, will last forever and is a snap to reinstall plastic when time comes. And for that size GH you may find a sheet of greenhouse film twice that size, or larger easier to find..so double it and install an inflater (old bathroom ceiling fan will work). You'll need a fraction of the heat and it will last longer...I'm now going on 11 years on my first GH plastic installed with a triple firring strip system to hold the plastic on. My 20x96 and 30x96 use the wirelock for base and roll-up sides and it is a blessing.

On last impression: think BIG and think FUTURE. You just know you're going to grow and you want something to hold up to 50 mph winds. Why not do it right the first time. I use PVC arches with rebar base stakes to provide support for row cover for winter protection of some herbs but then it goes back to the scrap pile. Most PVC structures I've seen use duct tape to secure the perlins to the arches. Is that the type structure you want to show the neighbors.

Well I've been to a few websites, and some I liked more than others, but my main problem is price. The cheapest price of plastic I could find was $0.09 per square foot, and I need about 1125 sq ft with the changes I made to the plans, and I have to spend approx. $100, which isn't too much, but I'd prefer spend less if I can. So is there anywhere where I get about that much plastic sheeting for a lesser price?
Also, what kind of paint can I use on PVC?

You didn't say where you live or what you want to use the greenhouse for. Also, the size of the greenhouse will determine how strong the PVC has to be. I built a simple hoophouse last fall that is 10 ft wide x 12 ft long and the PVC is 1" gray PVC electrical conduit. I like it because it is very sunlight resistant and it can use fittings like tees and crosses from 1" PVC water pipe also. It is simply attached to the inside of my raised beds (2 x 10 lumber) with conduit clamps. It held up under heavy snow loads this winter. The plastic is attached to the the top of the 2 x 10 by rolling it up in a 2 x 2 and nailing it to the top of the board.

I'm not sure what I will do during the summer because it will surely get real hot in there and I used construction plastic so I will probably remove the plastic and put new plastic up in the fall. If it works out well I'll probably get greenhouse plastic when I run out of the cheap stuff.

Heating is impossibly expensive if you are in a cold climate; in winter you can only expect the inside to be a few degrees warmer than outside unless you have a real big heater and an air-tight construction.

Bob B

"Second, with all the hoop-style greenhouses I've noticed there needs to be a bending of PVC. Is that really a good idea? Will it snap?"

PVC is very bendy when warm, just don't try bending the bows during a blizzard !

It's wise to put in a ridgebeam of 2x4's glued in a "T" shape to give the bows support. I attached my bows with "U" shaped conduit brackets.

"Use Schedule 80 PVC - it is heavier, grey (therefore more sun resistant). It can be purchased at most large discount stores, Lowes, Home Depot, etc."

Unfortunately Sch. 80 is a special order around here. I did the rebar-inside-PVC trick. I'd sure have ordered the Sch. 80 if I'd known I could.

"So is there anywhere where I get about that much plastic sheeting for a lesser price? "

I've canvassed the home centers and never found any good film wide enough. I don't know where that stuff came from the author of the plan used.

I found that I could use our industrial sewing machine to sew 10ft pieces of 6 mil plastic together.

However, you can buy cut yardage of decent four year greenhouse film.

I went to our local greenhouse and asked where they buy their plastic.

They'd just taken down their three year old plastic and put up new, so I said, "Can I buy the old film, please?"

They said "sure... oops. Cut it up for scrap."

So if you could find this kind of deal you'd have good plastic for a year or so.

Ask for testimonials from people who've bought recently. I used the cheap stuff and it has lasted a year with one or two small rips so far.

Or you can buy a "solar pool cover". It's a very good, thick type of film designed to be a good insulator.

A solar pool cover is peppered with trapped air bubbles and I wish I had one.

Ask CactusFreak, I think he uses one. People who do love it.

It costs more but if you want to have anything growing when snow flies, it'll pay for itself in the first year.

One important tip is to build the greenhouse with two foot high wooden sides.

These "kneeboards" give you much more headroom, and they reduce the length of the bows you'll need and, more important, they mean you can use a smaller piece of plastic to cover.

I sure wish I'd known that tip last year.

""And will it be hard to heat a hoophouse if it has big holes in the plastic (like near the ground), or is there a way I can make it near air-tight?"

You can set up the plastic to be rolled up toward the top of the HoopHouse when you don't need heating and roll it back down in the Fall.

That gives you lots better ventilation and prevents overheating. I'd like to figure out how to retrofit my hoophouse to do that.

*********

If you happen to have a hill on your property, there's a great money saver called a "Pit" greenhouse.

You still use the bows and cover with plastic, but you cut into the hill on the South side.

The earth forms the North wall, and insulates your greenhouse from the cold winds. Properly constructed, a Pit greenhouse will never get below freezing in Zone 5.

A clever trick is to dig down enough to put in a walkway in front of the plants. The cold air that creeps in sinks and fills the sunken walkway where the earth warms it to above freezing.

We have two hills that might work, but I'd end up killing trees to do it. :(

I built a PVC Greenhouse on my roof deck. I am putting together a site with setp by step instructions.
this site

Here is a recent image of the inside. I wish I had planned a bigger structure {{gwi:294795}}

enjoy

Sorry about that. My last post contained HTML errors of my own doing.

The two sites are:

My step by step site

The other site

An interesting way to add heat is to keep rabbits. I think they add about a degree/bunny. Also Greenhouse/grower supplies sell greenhouse covering that is like bubble wrap. It is smooth on both sides with about an inch thickness holds heat in pretty well. My neighbor uses an old coal burning stove with a pump and some copper piping around the base of the greenhouse..like baseboard heating in houses.

Rabbits! I never thought of such a clever idea. Wow. The wheels are spinning now. Thank you Kevlarster!
~tom

You can work out how many you need by figuring out the heatloss of your gh per hour, one rabbit will generate about 58.53 btu/hr. Chances are you will need 100-200 bunnies to make a difference. where are you going to put that many :)

The bunnies won`t like summer temps in the gh so you`ll also need to move them outside in summer.

no shortage of manure :)

how can you lose? good eating. good manure for composting. added heat for the greenhouse. ah, but if a 100 is needed, that would take quite a few months and too much space.
The wheel stopped spinning. Thanks Hex
~tom

i know this fall/wnter. i'm going to close off the top part of my green house, so the heat does not go all up there. and somehow i will direct it down, i'll have all spring and summer to figure that out. but i figure with all the extra plastic i have i can tape it up to were i want my ceiling to be. and not have my plants die. i will do this when it gets cold the first night, otherwise i'll push it off and then i'll not do it til it's tooo late. LOL like i do with the windows, i do like the idea of the heat on the bottom!! neato idea!!! man that's what i need in my house!! my floors are always cold!! (old house)

Hey Tom
Talking of wheels, a couple of fitness fanatics on exercise bikes would generate plenty of heat ;)
If you hook the bikes up to an alternator you might even store enough power to tide you over until they arrive the following day :)

Guys, you all might want to check out this site. You may be surprised at the cost of the frames. We've put up 3 of the 16 foot wides and 2 of the 24's. The small houses are rock solid but I kinda wish the larger ones were out of a slightly larger pipe although we have not had any problems and we LOTS of wind here. We do put solid wooden ends on the houses. Our large greenhouse is a totally different design and its built like a tank but we bought it used.

Of the three smaller ones, one is a greenhouse, one is used for a cold frame, and the other one is just the frame to hang baskets in without any covering. The first 2 houses have 5 purlins and the basket house has 7.

Now, his prices are a little steep for some of the other things you might need but we've been really pleased w/ the frames. And he will deal with you.

If you need any more info, let me know.

Regards,

Tom