Polytunnel build - what sliding door hardware?

[alex robinson]

Spring is underway and I have recently got a new allotment. I have been thinking about what to grow and more than any particular vegetable I have decided I want to grow a large polytunnel.

Looking at new kits they were either incredibly expensive, or incredibly flimsy. Second hand commercial tunnels were good per square metre, but enormous, so I decided to build one out of 63mm mdpe water pipe, slid over scaffold poles. Overall size is going to be about 8 x 5m. (Pictures to follow at some point).

Constructing the main frame seems fairly simple. I have been wondering about the doors however. Ideally I would like a sliding door. Currently this: https://www.fhbrundle.co.uk/sliding-door-gear/max-door-weight-60kg-ibfm looks a good option. Does anyone have any better suggestions or bright ideas please?

Ideally the doors would be 2 part - one layer with polythene for the winter, and a second mesh layer so as to give ventilation in the summer. Again, any elegant suggestions please? I cannot picture a very neat answer either going for 2 layers of sliding doors, or a 2 layer door that folds and slides!

 

[Tris]

Whatever you choose you will need something for them to run on at the bottom otherwise they'll blow about like sails. Simplest method is angle iron set in concrete so you've got a vertical metal strip, then fashion a guide for the door bottom that runs on the strip

Personally I'd keep it simple with a pair of hinged doors either end, poly one goes outwards, mesh one goes inwards

 

[alex robinson]

Whatever you choose you will need something for them to run on at the bottom otherwise they'll blow about like sails. Simplest method is angle iron set in concrete so you've got a vertical metal strip, then fashion a guide for the door bottom that runs on the strip

Personally I'd keep it simple with a pair of hinged doors either end, poly one goes outwards, mesh one goes inwards

I would have expected a bottom rail was needed (hassle and large concrete pours are frowned on at the allotments!) but looking at pictures of some of the professional ones, to my surprise, they appear not to bother.

Doors pivoting inwards aren't ideal as they take up a lot of space. First the space for the door itself, then the space to get a wheelbarrow past it. As you say though, simple is good!

 

[Tris]

Never had a problem with inward pivoting doors, although on our tunnel I made 3ft doors and allowed space for them to fold back a bit. When we put it up here I rehung them to swing outwards, works but more wind prone.

Looking at first tunnels website I'm not sure about the flimsy looking roller pegs they have for the bottom restraint on their sliding door.

Maybe cannibalise a greenhouse frame for the doors? There's often freebies to be had

 

[TheUnicorn]

In my experience, the constant wind, rain, sun, and ground movement means that you always get a lot of movement in doors and frames on tunnels, I would anticipate that and make sure you have the ability for adjustments.

On the subject of a bottom rail, I wonder if a sleeper would be an alternative to a concrete base