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Omaha, NE (N41-15-42 )

I finished my arched greenhouse just before the snowstorm hit this weekend. I wanted to share my pain with everyone in the event I can prevent someone else from having the same pain.

I followed the plans for the greenhouse we have at PumpkinSupply.com, except that I couldn't find affordable 20 ft. PVC pipe for the arches. So, without giving it too much thought I took two pieces of 10' PVC and connected them with a coupler, and glued everything in with PVC cement, and everything seemed fine (for the first few hours) I had heaters inside to keep the snow from accumulating on top of the greenhouse. But every 12 hours or so, one of the arches would snap right at the coupler. Because of the supports, it was more like a teepee, and kept the structure from completely collapsing.

After giving it a little more thought, it occurred to me that having the weakest point in the arch positioned at the highest stress point was probably not the brightest thing I could have done. So instead, I replaced the fallen arches (makes your feet hurt, doesn't it) with a setup where I had 2 5' pvc lengths on the sides and a 10' pvc length over the top. This proved to be much more stable. I also used our 5-way X fittings rather than the slip fittings for connecting the purlins.

This might be second nature to many of you, but I chose to take computer programming instead of shop class in Jr. High, so I've never been too bright with regard to the structural integrity of things.

I will try to post some pictures later on in my diary (Which I have yet to start), but wanted to share my experiences in case others were going down the same road. Other than the fact that I couldn't find 20' PVC pipe, the plans we have on the site worked really well.

Matt

3/21/2006 3:39:31 PM

Newcastle England

nice one,good of you to share the info,i might have put it down to experience and not told anyone let alone the pumpkin world,well done.peter

3/21/2006 4:03:02 PM

Long Island,New York

another option is to add a 4 ft length of number 4-(1/2 inch) rebar into the pvc at that coupling....2 ft inside one 10 ft section the other 2 ft into the opposite 10 footer just to reinforce the pvc at the peak.......G

3/21/2006 4:04:49 PM

No Place Special

Matt u crack me up! I was thinking along the same lines as G with reinforcing it. Good luck. How much snow you boys get?

3/21/2006 7:14:23 PM

Norton, MA

I made a similar mistake a couple years ago on much smaller houses. I tried to put a wood piece across the top to hold the arches in line. I bolted it there (holes in the PVC) and I went out to the patch later and they had all snapped! I just duct taped it all up. AleX Noel.

3/21/2006 8:50:57 PM

Buffalo, MN ([email protected])

Matt I'm about to do the same, what type/thickness of PVC are you using? I'll also be runnung a 2x4 on top to keep the arches in line and so I can support it from the bottom. Wasn't planning on cemeting anything but the doors.
It sounds like it would be a good idea to put in rebar.

3/21/2006 9:23:32 PM

Omaha, NE (N41-15-42 )

I'm using 1" PVC. Used two different thicknesses (different pressure ratings), but they both behaved the same. I have to say though that the new design with connectors on the sides rather than the top is working quite nicely. I have not needed glue anything for the new hoops. So, for the people doing the rebar, I'm trying to envision it. Do you have to bend it first, or does a 4' piece of rebar bend on its own?

3/21/2006 9:44:39 PM

rebar works,,so does another piece of pvc smaller diameter that just fits inside the 1" or whatever you are using,,24"to 36" internal support, split the distance on each side of the joint, lighter and easier in my mind to use.I also use this for the ridge and purlin when joints are required.. I do use 36" rebar stakes in the ground for anchors. 1'x4' at the bottom of the plastic with hook and eye's for rolling up when venting.

Does anyone use the 5 way connectors with a veritcal leg run down to the ground for support? I'm thinking of using these this year with short sections for the ridge. The purlins I snap tie and tape to the rafters.

3/21/2006 9:45:20 PM

San Jose [email protected]

You can bend sch 40 pvc pipe with heat, thus eliminating stress on the couplings, I have used,

"plumbers torch"

gas bbq

tail pipe of vehicle

gas kitchen stove

for those of you in the country, use your burn pile

make sure to keep an eye on it, don't just let it be, keep turning the pipe or it will burn

also not a good idea to breath the fumes

Gary

3/22/2006 7:38:36 PM