Gwilym :: January 10th, 2020

We live on a big piece of rural land and pretty much built everything the wrong way round. We built the house first, shed second and lately the greenhouse last. Next time, if there is one, I think we'll do it in the reverse order.

Because I like to think about things too much we of course did not buy a greenhouse kit, but designed it from scratch. This meant it took quite a few more years than it should have. But I reckon it is pretty cool!

The greenhouse under construction

Design parameters:

  • It needs to be strong as it gets windy round here!

  • Ideally it would have a shade cloth part to raise plants and moderate heat as well as the classic plastic membrane section.

  • There would be some sort of barrier from the outside at soil level to stop weeds getting in and make it easy to mow eat up to from the outside without damaging the membrane and weed up to from the inside.

  • Like everything we've built I'd like it to last a long time and when it does die for as much as possible of the materials to be reusable in another project. Also if it can be built with recycled materials all the better.

  • No treated timber anywhere. No PVC.

Here is how it turned out:

Design decisions made and initial thoughts on if they were the right ones:

  • The frames are from standard 6.5m lengths of galv steel pipe bent with a basic hydraulic pipe bender at 5 points. I figured it would be stiffer than alkathene pipe which is what people are using around the district for greehouses but which still requires strengthening to make it rigid enough. It's also a cheap way to achieve strengtha nd steel is recyclable.Creating the bends was pretty easy with Gus's pipebender. These frames work great, inititally I thought we had the top pitch too shallow but with the plastic tight we don't get any pooling on the top during rain storms (water is heavy and would potentially bend everything).

Greenhouse under construction

  • Initlly we banged some metal stakes into the ground and sat the frames on them thinking that would be enough to stop them sinking. As the soil got better in teh greenhouse though it got softer and the frames sank, we had to re-found them by digging down and sticking some concrete under them. Problem solved, shoudl have done that to start with.

  • Joining the frames together are lateral pipes the same as the frames joined with pressed pipe fittings

  • Along the length at the base we put roofing tin into the ground and wired it to the frames. The thinking is that prevent uplift and the thing flying away, give a good edge on the outside to mow to and lift the bed level up a bit to make it easy to work on. The tin does have paint on it which I guess will eventually make it's way into our food, we figured it's the best of available options and the actual amount of coating is very small and distributed over a long time period we'll be ok. Fingers crossed.

You can see the tin running the length here

  • It would have been better to make the end wall out of metal pipe and plastic film too, as any timber indside the envelope is doomed to rot eventually. This time round though the south end we made from macrocarpa timber and battened the film on. I have some ideas about putting an inner ring of bent pipe inside the end wall which I think would work. The North end is wrapped and then has a mesh zipped door.

Greenhouse under construction

More pictures coming soon now it's been up for almost a whole year.