I'm planning to build a small hoop house for starting plants in and maybe for growing in as well for the shoulder seasons. I am having an issue with the dimensions of the plastic. As I'm trying to do this on the cheap, I don't want to buy a roll too much larger than I need, but when I was at Lowe's today I saw they have 10'x25' foot rolls, and then 20'x100'. My dimensions were going to be more like 20'x15' or something like that. That is, 15' in length and 20' for the length of the hoop arcs (for an interior width of around 12'). So the one is too small and the other way too big.
My question is, is there a good way to use the stuff that's only 10' wide and then join the two sheets in a durable way to make it cover the wider structure?
A greenhouse supply place should have poly mending tape that will stick real good to the plastic sheeting. I've used it in the past on greenhouse poly covering to repair holes and tears.
By the way, the non-treated poly that the department stores sell will degrade fairly quickly in the sun. Depending upon how strong your sun is, expect one or possibly two seasons from it. Here in Hawaii it only lasts 9 months before it tears along the folded lines.
It's never too late to start! I retired to homestead on the slopes of Mauna Loa, an active volcano. I relate snippets of my endeavor on my blog : www.kaufarmer.blogspot.com
I would strongly encourage checking out AM Leonards remnant sale website... http://iteminfo.amleo.com/poly/ - I've gotten a bunch of poly from here and have been happy with it. And it's actual greenhouse plastic so you aren't getting the false economy game of cheap, unstable poly from lowes and having to futz with it to get it to do what you want... Hope this helps.