My experience is that PVC fittings break. PVC pipe bends in ways you don't want it to bend. If you're determined to use PVC anyway, study how metal pipe frame greenhouses are built and try to do something similar on a smaller scale. Make bracing connections to more PVC (or wood) using metal plumbers' strap and nuts and bolts. This will allow more flexibility in the joints. I've got plenty of broken pipe and twisted carriage bolts to show what a direct bolt hole through the pipe will do. If you have to put a bolt through, glue in wooden plug reinforcements to drill through. If you're going to sleeve PVC over rebar, sleeve a smaller bit of PVC (longer than the rebar stub) inside first to reinforce and spread the load at the pressure point. If you want advice on your build, post pictures of what you have in mind. It's hard to envision exactly what your structure will look like from just "a PVC greenhouse". Tell us about size and height. Tell us about shape (gothic arch, gable, round arch, low arch on kneewalls like Jay Slick's, etc). Tell us about frame spacing and what you'll have for purlins. I personally like wooden strapping and wood block gothic arch frames. They're easy to build, cheap, shaped to shed snow and wind, and they're very strong. You can fasten to it easily. In my limited experience, PVC is only suitable for very small houses, or for houses that will be disassembled and moved periodically on the shoulder seasons and left uncovered (no snow/wind loads) in the winter. Here is a link that might be useful: Gardening The Hard Way

"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. :(

You are not permitted to run any other wires in the same conduit that contains class 1 conductors. Wires coming from a sub-panel are class 1. For the phone line, buy the cheapest roll of black water pipe. I'd use one inch ID because you never know when you might want to fish in another wire for an intercom or some other class 2 device. The #8 is plenty heavy enough to deliver 40 amps to a sub panel but you should have 3 insulated conductors plus a bare copper ground wire. Why take just 115 volts out there? Take 230. It's the same amount of work and you double the available power. If you buy a bigger compressor or a Mig welder, then you will kick your butt for not putting in 230 now. If the roll is 2 conductor plus a ground, then you should have a black and white plus the copper ground. Just buy some black #8 single strand to give you the extra pole for the 230. Use the gray PVC and I'd suggest 1 1/4" ID for that run.

PVC is used to make pipe for a number of different applications. PVC pipe intended for "Pressure Piping" is made to ASTM D-1785 and is manufactured to IPS size specifications conforming to IPS sched 20, sched. 40, sched. 80, sched. 120 and sched. 200 Fittings intended for pressure piping will have sharp angles and are identified by the inside diameter of the pipe. All elbows are listed by the change in direction expressed in Degrees. I.E. 90 deg elbow, 45deg elbow, 22.5 deg elbow etc. PVC pipe intended for use in DWV (drain, Waste & Vent) applications is made to ASTM D-2665 and is only made in IPS sched 40. (Per code, only schedule 40 PVC may be used for DWV applications.) (Note-sched 40 PVC pipe will normally be labeled under both ASTM 1785 & ASTM D-2665 and can be used for either pressure piping or DWV) Fittings intended for DWV application will have a radius bend at all changes in direction and they are identied by the fraction of a circle represented by the change in direction. I.E. a DWV grade 90 degree elbow would properly be called a 1/4 Bend and a 45 deg DWV elbow is called an 1/8 Bend, etc. Tee's and elbows will be prefaced by the term "DWV" or they may be listed as a "Sanitary Tee or Elbow". The may also use the contraction Sani to indicate a DWV fitting such as a 3" Sani-tee. Code requires that every structure must have a "Main Cleanout" within 3' of the point where the line exits the structure. All drainage and vent lines within the structure are defined as DWV lines (Drain, waste & vent). The line from the main cleanout to the municipal sewer tap or the septic tank is properly defined as the "House Sewer Line" and any lines intended to convey storm drainage to a Storm Sewer or storm drainage ditch are defined as "Storm Sewers" When the first started making PVC pipe it was intended to be an alternative to Galvanized Iron Pipe, therefore the pipe is made to the IPS standard, meaning that the pipe size and wall thicknesses compare to the specifications for the metal pipe, hence the use of the IPS standard. The pipe that you have is intended solely for sewer use, thus it is made to the same standards as set forth for vitreous clay pipe and concrete pipe, that being the SDR (Size dimension Ratio) standard. Under the SDR standard the thickness of the pipe wall can be determined by dividing the pipe diameter by the index number. By example, you have 3" SDR 30 pipe, which means the actual wall thickness of the pipe is 3" / 30= 0.1". When you go to your local hardware or home supply store you will find that they have all three types of pipe and fittings but they stock them in different locations to insure they don't get mixed up.