A permanent polytunnel: step-by-step build

In short

• Hoops of 32 mm galvanised tube, spaced 1.25 m in the lowlands, 1.0 m where there is a lot of snow.
• Every hoop stands in a 42 mm foundation tube set in a concrete footing below frost depth.
• Braces at all four corners and a ridge bar stop the tunnel leaning in the wind.
• The film goes on on a warm, still day, with four people, anti-drip side inwards.
• Wet snow on 50 m² can weigh 5–6 tonnes: knock it off, and in snowy areas prop the ridge in winter.

What's inside

Chapters

1. The project on one sheet
2. Snow and wind: how a tunnel stays in one piece
3. Setting out and preparing the ground
4. Foundations and anchors
5. Hoops and rails
6. Ends, doors and top vent
7. Side ventilation
8. Fitting the film
9. Inside: beds, paths and water
10. A timber greenhouse with polycarbonate
11. Most common mistakes
12. Printable checklist

Worksheets

• Shopping list for a 5 × 10 m tunnel
• Material calculator
• Cost calculator
• Build plan
• Tunnel sketch
• Build and maintenance log