So we now have a truly fantastic greenhouse that we built ourselves! This post will take you through the process of how we built it, step by step, in case you ever have the opportunity to build one and want some tips. It’s a very rewarding experience, I highly recommend it.
The first step is to lay out the dimentions of your greenhouse and pound in lengths of rebar, which will act as a sort of foundation. We used 36″ lengths of rebar, and pounded them in until just 9″ was
still showing above ground, leaving 27″ underground to have a good hold, and act as a solid foundation. We built a 12′ x 30′ greenhouse, with a total of 10 PVC ‘ribs’, so we placed 10 pairs of rebar 12′ apart with 40″ spacing between each one.
The next bit of material was 10 20-foot lengths of 1″ schedule 40 PVC, which acts as the “ribs” of the greenhouse, providing structure and giving the greenhouse it’s tunnel shape. We removed 3″ from each length of PVC to be sure that there would be enough plastic to stretch over the whole thing (although this ended up being unecessary, as there was plenty of plastic left at the bottom when we stretched it.) We then slid one of PVC over each bit of rebar on one side, then bowed it over so that the other end could slide over the paider bit of rebar on the other side, creating 10 white arches about 6′ high and 12′ wide.
Next up we attached a 2×6 board outside the arches, along the bottom on both sides to complete the foundation. Because the greenhouse is 30′ long, we needed 3 20′ 2x6s – we cut one of them in half to get a total of 30′ down each side. We attached each PVC rib to the 2×6 base board on both sides using plumber’s strapping, which worked quite well – and was also good for attaching the 2x6s together to make a continuous 30′ peice on ech side. We did need to dig in some spots to make the base baord could lie flat on the uneven ground.
Next is the most exciting part: putting the skin on; ie. stretching 6mm UV resistant poly over the ribs to make it a greenhouse. Just before doing the skinning, we also added 1/2″ sched. 40 PVC down the full length of either side, near the top, attaching it to each 1″ rib. This will give the ribs some structure and ensure they don’t move around too much, and it also gives us something to hang string from for training our tomatoes! To skin the greenhouse we bought a 100′ long roll of 20′ wide poly (we have many uses for the ewtra length), and cut about 45′ (30′ to cover the length of the greenhouse and 7.5′ at each end to close it off and make doors). We made sure it was evenly stretched over the structure and tight at the ends, then we tacked in one side – screwing 2″ wide strips of plwood through the poly and into the 2×6 baseboards to holit in. Once one side was done, we wnt to the other side and stretched the poly down almost as hard as we could – it helped that it was a hot sunny day, so that we could get some extra stretch out of the poly. With two people holding the poly taut, and one person screwing in plywood strips, we made ourselves an nice tight poly tunnel greenhouse.
Check out larger photos in the gallery: