We've built this tunnel for Kev and Sue, who both work part-time here at Da Barn. It's based on everything we've learned building and maintaining the 5 tunnels at Da Barn.
Our tunnels are hybrid polytunnels, using commercial polytunnel sheeting with solid ends. A polytunnel if built right can be extremely robust, but there are some key points that must be got right.
At Da Barn we would always recommend customers investigate buying a Polycrub before
considering a poly tunnel. Polycrubs are built using polycarbonate twinwall sheeting for the cover, which leads to a robust structure that is designed for our local conditions. The structures have had all the necessary engineering calculations done to prove they are strong enough to last. Polycrubs are provided as kits that you can build yourself or have a local builder build for you.
This tunnel, and others that we build for our own use, use a similar structure but rely on
commercial polythene sheeting for the cover. We don't sell complete kits, but are able to sell you components for your own build.
Key points that we've learned over the years that make these tunnels last in Shetland:-
- The ends are the weakest part of the structure. Using polycarbonate or timber in these areas greatly reduces the chances of losing the cover.
- The polythene is incredibly strong. Much like an eggshell, it bonds the whole structure together and takes the load off the hoop to frame connections. Loose covers will flap in the wind and have a hugely reduced lifetime. We expect at least 6 years of life out of one of our covers.
- Fixing of the cover to the frame is a critical point. A fixing system that allows adjustment is essential to get a tight and wrinkle free cover.
Over the next few weeks we will post a number of articles covering the build of this tunnel and explaining the key points of how we built it and what parts we used.