SteelRoot · Galvanised-steel arch
Galvanised steel,
for storm-exposed plots.
40 × 20 mm closed RHS galvanised steel with ZAM coating. 0.67 m arch spacing — the spacing UK exposed sites need, not the wider Continental default. 6 mm cellular polycarbonate, screw-fixed. Ground anchors included, one per metre.
Shop the SteelRoot →One product line.
Five lengths. Same engineering.
The SteelRoot 3.14 m line ships in five lengths — from the 12.56 m² 4 m for a starter quarter-allotment to the 37.80 m² 12 m for serious year-round growing. Same galvanised-steel arch profile, same close 0.67 m arch spacing, same 6 mm polycarbonate, same included anchors. You choose the length.
The 8 m is the most-ordered length — small-allotment scale with two full growing rows plus a working path.
The product
From £1,199.00
The full SteelRoot 3.14 m range, on one product page. Pick your length — 4 m (£1,199) through 12 m (£1,949). Made-to-order in our Polish workshop, ships to the UK in 3-4 weeks from order. Designed for plots Continental greenhouses give up on.
Explore the SteelRoot →Four engineering decisions
that hold the structure together.
SteelRoot's spec is deliberately different from the Continental hobby-tier default — and every choice is published openly, with the reasoning, before you order.
UK exposed-site spec. Closer arches cut panel deflection (deflection scales with the cube of unsupported span). 7 arches on a 4 m, 19 on a 12 m — roughly 40 % more frame-to-panel intersections than the Continental 1 m default.
About 33 % better thermal retention than 4 mm twin-wall, 50 % better than single-pane glass. Stiffer between supports — only a steel arch can carry the cross-section safely.
Hot-dip 40 × 20 mm closed RHS with zinc-aluminium-magnesium coating. ZAM gives self-healing edge protection at scratches and drill points — the coating chemistry passivates as the structure ages.
One bent-L galvanised steel anchor per 1 m of length. UK competitors typically sell anchors separately at £60–110 per screw. A greenhouse without anchors isn't a finished product — it's a sail.
Built for plots
Continental greenhouses give up on.
10-year anti-corrosion frame warranty. 2-year polycarbonate defect warranty. Wind-gust + Named-Storm exclusions published openly before you order — not in the post-purchase small print.
Read the full warranty →