Man using the Pythagoras' theorem to construct a polytunnel

One of the main challenges when building your polytunnel is getting the corners square, and we recommend getting the corners as close to 90 degrees as possible. The 3-4-5 method, otherwise known as Pythagoras' theorem, can be applied to ensure that all the parts of your polytunnel fit together as planned.
To begin constructing your polytunnel, you should position the first two foundation tubes the correct distance apart. These are marked as ‘A’ and ‘B’ in the diagram below. Make sure to measure the distance between these tubes carefully and put them no more than a few inches into the ground in case they need to be repositioned.
You should then secure a tight string-line between the two foundation tubes and mark the 120cm (or 4ft/8ft) position, labelled ‘D’ in the diagram. We recommend using a small cable tie or wire twist for doing this, as it can be removed if required, but you can also place a marker stake into the ground if you prefer.
Diagram showing how to space polytunnel tubes using the 3-4-5 method
From the same corner, connect a second length of string to the foundation tube marked ‘C’. At this stage, ‘C’ is not secured into position. Ensure the string-line is tight and mark the 90cm point (or 3ft/6ft), labelled ‘E’. Now measure the distance between ‘D’ and ‘E’, this should be 150cm (or 5ft/10ft). If not, then reposition foundation tube ‘C’ (with the tensioned string-line still attached) until the distance between ‘D’ and ‘E’ is correct.
Foundation tube ‘F’ should now be pushed into the ground. If positioned the correct distance from ‘A’ and ‘C’ it should be in the correct position. Once you’re happy that your corner foundations tubes are square and in the correct position you can screw them all into the required depth.
As a final check, measure diagonally from corner to corner, these two measurements should be the same. If not, then repeat the 3-4-5 triangle method until they are. Once the four corner foundation tubes are in place the intermediate foundation tubes can then be positioned. These should be spaced at 5ft (1.52m) or 6ft (1.83m) along the length, depending upon the hoop spacing option you have chosen.
For more advice, download a PDF copy of our instruction manual or watch our construction video below.


How to Build Our Easy-Build Polytunnel

Before you begin to build your Easy-Build polytunnel, we strongly recommend you read the instructions thoroughly. We've also put together this instructional video to provide more advice. The Easy-Build polytunnel is by far the quickest, easiest and most durable on the market, and now comes with a lifetime guarantee.