Mike, With all those connectors, you would spend a small fortune. I am glad you are looking at cutting them out. I would suggest that for the side wall attachment on the bottom that you drive a 1 1/4 inch PVC pipe I foot long into the ground and slide the sidewall/bow pipe into that. I will try to find a picture to show you. This way you don't have to try to attach it at two places. Also, If you are going to go with a one piece hoop, glue the 45 degree elbows to the side pieces and leave the rib connection unglued. The down pressure from the plastic will keep them together. The elbows will come off in fierce windstorms, not as big of a problem after I started to glue them. Also if a rib breaks, you can easily replace them. You can bend a piece of chainlink fence top rail to match the plastic hoop. I used my endwall pipe and attached more 2 by 4 pieces under the pipe and attached the pipe to one side and "walked/bent" it over the hoop. It was fairly smooth. That is what I am doing this year to add some strength. My building is 18 feet 6 inches. You could make your 20 by adding probably 3-5 more feet of pipe to the 20 foot rib. If you do this make sure you buy the pipe that has the bell end. (FYI it is a built in connector that you can connect two pipes together. This connection is stronger than the connectors you buy at the store.) You can add a side support 2 by 4 like my center one on each side. I was going to do this and put the post in the row of tomatoes. That way it would not be in the way. Snow is a concern and if you are patient and diligent, you can sweep it off and you will be fine. The light fluffy stuff isn't a problem, the wet slushy stuff is a nightmare! When I build my building, I had plans like yours. I read everywhere and I figured my costs. If I wanted to build a steel frame building the same size as mine, it would cost 4,000-5,000. I could not justify that expense. Mine cost $500-$600 depending on how you account for materials on hand and cheap buys on craigslist. I decided I would get up at 2 am and sweep snow if it was going to save me $3,500-4,500 up front. I also am concerned about tornadoes here in Kansas. We have had close calls from them every other year for the last 6. This is an on year. Close calls means, tornado on the ground with in a 1/4 mile of my house. We will see what this year brings! Good Luck.

dave i just use auto openers and cheap clearence fans,cheap heaters,and cheap gutter cables.i did put a line of misters down the ridges and it works great when it warm and sunny but i need to adjust them better.extra clips are the way to go.this fall i will do some alterations to make it cheaper to heat. i will take out the poly from the roof and walls on the north side and double them on the south side with an trapped air space like a thermal window.and insulate the north wall as much as i can.i also want to insulate the floor better.maybe one of those clearence blue flame heaters will see.oh yeah the doors are a pain i might put hinges.i will post pictures when i do it. heres a tip dont buy anything unless your sure you need it like an automated super duper fan with shutters if your just starting plants and extending your season or build any thing that cant be moved quickly out of the house its very small and you will probaly want to move things around depending on the season.good luck. rob

Thanks SD grower, I've been pretty envious of some of the HDPE being sold to NFT growers in San Diego from hydroponics outfits. The problem is I can't make use of a pallet load freighted to me, and even in sample amounts the 10-12' channels I've looked at would need to be cut in half and for stubby channels, even UPS shipping of that alone (only 30-50 feet or so) is over $100. and this with the short lengths. I've not found a *smoothwall* irrigation product that is 6" anywhere to tell the truth thought I'm sure it's out there, except for the PVC. As you knew and I found out, all potable water lines are extra thickwalled, which is cost prohibitive in anything above 2". I did find locally one interesting product. It is an HDPE/HDPE thin white smooth sleeve over a conventional standard black corrugated, with smooth interior black pipe, dual construction. I have questions about that though to resolve. Like will the corrugation be generally causing more places for micro-organism growth and how well can I cut holes in it in either a vertical or NFT horizontal slope. I would have looked further since it is economical, but the black HDPE for these economical options is probably not a good idea for a recirculating system, it seems a bit too much in my perception of this. One thing is a small length of it but another is 50' which warms up and was made from: "Smoothwall Pipe [from ADS] is made with recycled HDPE from post-consumer and industrial sources..." If we can't find NSF material like potable water PVC, the least I can try for is virgin material and chat with the manufacturer just to be sure there is no additive to avoid. Even with regular irrigation pipe wherever I would find that, it is no big deal since most of the big diameter is just for sending run-off to the sewer, and the standard is basically just one pass into the fields. That SDR 35 storm drain stuff Cole mentioned is available in all virgin PVC for some reason and intermediate thickness (just need to find out what sort of hardner they are adding, but likely this is good material), so it could fit the bill in some cases. If I had a local source for the 6" potable PVC at the lowest end of the range ($4/ft) you got available at those places, I'm in. But where I'm at by now it feels like I'm chasing windmills. Onward Sancho Panza :(

love this forum that you can do a little diy advising! ok the mold in the supply boxes and on the grills probably isn't from the duct takeoffs @ the plenum. it takes a long time for mold to travel that far..and if there isn't moisture & food source it won't spread to that area. it isn't always mold..sometimes it is just dust. so mold/dust buildup at the ducts @ plenum is lack of proper air seal. mold in supply boxes & on grills is lack of proper air seal at the cut in the sheetrock ceiling where supply grill is attached to the box. nine times out of ten..you can solve the issue by sealing supply boxes to sheetrock. see attached picture. hardcast brand #1402 mastic tape is used to seal supply box to sheetrock. this tape is 3" wide. I split the 3" into 1 1/2" lengths. stick to sheetrock and fold into supply box. as the tape adheres to many surfaces you need to be careful to keep it within the area covered by the supply grill. once it sticks to the sheetrock..you'll lose paper if you try to move it. surfaces have to be clean & dry for tape to adhere. and once in place you'll want to press it in place as it is somewhat pressure sensitive. the tape is strong enough to keep the box tight to attic floor on the attic side when installing the supply grill. wash the dust off the grills, wipe inside the supply box & into the duct. reinstall the supply grill. oh and when you remove the supply grills..take a sharpie and mark what direction they faced (throw to window..dirveway side whatever note you need to put them back in same position) this way you'll put them back as they were. I've tried several other brands of mastic tape. hardcast 1402 is the best. the others are 2" width and mastic is thinner, resulting in less strength and useful life. why would I chose spray foam for my floors? I've sealed floors several ways, foam is the easiest albeit more costly, once prep work is done. there isn't enough room to physically install foam sheathing to the bottom of the floor joists. I'll seal any big holes..like under tub then do 3" foam. I've looked at froth packs like tiger foam..but having worked with so many foam companies locally, will just have them do my floor when they are in my area. the software is pricy. we lease it yearly. once upon a time we bought the cd..but too many people abused it. so now it is a download & upgrades to original install. a lot of mastic isn't always an indication of a good seal. it doesn't take a lot if you put it in the actual leaks. you can feel around the duct take offs on the plenum while unit is running and feel some of the leakage. also checking plenum connections to the equipment at the same time. I use mastic tape to connect plenums (after screwing them in place) much easier to seal under the plenum to equipment with tape than painting mastic upside down.