SteelRoot Plot 3.14 · length calculator
Which length do I need?
Every Plot 3.14 stands on the same 3.00 m. Only the length changes: 4, 6, 8, 10 or 12 m. Three questions and one measurement give you a length, the reason for it and the space it needs.
What do you want to grow?
Choose the one closest to your plans. Each answer is one of the five lengths.
Will you want more room in a year or two?
Between two lengths, take the longer one: the step up is £200–£300, small money next to rebuilding later.
How much clear space do you have?
Measure between fences, walls and buildings. The manual asks for 2 m clear all round and nothing overhanging the roof: you need room to carry a 6 m sheet round the frame.
- 4 m—
- 6 m—
- 8 m—
- 10 m—
- 12 m—
No tape to hand? Skip this step: the result shows the space each length needs.
How exposed is the plot?
This changes the build, not the length.
All five, side by side
What does each length give me?
The same greenhouse five times: only these numbers change.
Swipe sideways to see all five.
| 4 m10 × 13 ft | Most popular6 m10 × 20 ft | 8 m10 × 26 ft | 10 m10 × 33 ft | 12 m10 × 39 ft | |
|---|---|---|---|---|---|
| Good for | Tomatoes, salad and seedlings | Salad and tomatoes all year | Most of our veg under one roof | A serious kitchen garden | Growing to sell |
| Floor area3.00 m on the ground × length | 12 m² | 18 m² | 24 m² | 30 m² | 36 m² |
| Bedstwo beds about 1 m wide, a path between the doors | about 8 m² | about 12 m² | about 16 m² | about 20 m² | about 24 m² |
| Archesat 1.00 m / at 0.67 m | 5 / 7 | 7 / 10 | 9 / 13 | 11 / 16 | 13 / 19 |
| Polycarbonate sheets2.1 × 6 m each | 3 | 4 | 5 | 6 | 7 |
| Ground anchorsat 1.00 m / at 0.67 m | 6 / 8 | 8 / 10 | 10 / 12 | 12 / 14 | 14 / 16 |
| Roof vents we suggestoptional, one for every 2 m | 2 | 3 | 4 | 5 | 6 |
| Base to build | 3.2 × 4.25 m | 3.2 × 6.25 m | 3.2 × 8.25 m | 3.2 × 10.25 m | 3.2 × 12.25 m |
| Clear spacethe base and 2 m on every side | 7.2 × 8.25 m | 7.2 × 10.25 m | 7.2 × 12.25 m | 7.2 × 14.25 m | 7.2 × 16.25 m |
| Price4 mm sheets, 1.00 m arch spacing | from £899 | from £1,099 | from £1,299 | from £1,599 | from £1,799 |
| Configure | Configure | Configure | Configure | Configure |
Before you choose
What decides the length?
Eight things, briefly.
Count beds, not floor
Paths take room. With two beds about 1 m wide and a path between the doors you plant about two square metres for every metre of length.
Between two lengths, take the longer one
The step up is £200–£300: small money next to rebuilding in 18 months.
Measure the space first
The base is 3.2 m wide and your length plus 0.25 m. The manual asks for 2 m clear of any fence or building, and nothing overhanging the roof.
Level over the whole length
5 cm of fall over 6 m is enough to stop the doors closing. The longer the greenhouse, the longer the level base you prepare.
Wind and snow change the build, not the length
On an exposed or snowy plot choose the 0.67 m arch spacing and 6 mm sheets, whatever the length: more arches and fixings, a stiffer sheet, the strongest build we make.
Planning: check before you order
At 2.02 m the Plot is under the 2.5 m limit for building within 2 m of a boundary. Length matters where an area limit applies: protected land, a conservation area, a garden already half built on, an allotment with its own rules.
A longer house needs more air
Both ends have doors whose upper halves open. Roof vents are optional; our working rule is one for every 2 m of length.
Delivery is the same at any length
Every length arrives on one pallet and uses the same 2.1 × 6 m sheets. A longer one has more arches and sheets to fit, not bigger ones.
How we work it out
- Floor area is 3.00 m, the width on the ground, times the length.
- Arches, sheets and anchors are the counts in the assembly manual.
- The base size and the 2 m are the base plan and the manual.
- Bed area is our arithmetic for two beds about 1 m wide and a path between the doors.
It is a guide, not a survey. If the plot slopes or is an awkward shape, send us a sketch before you order.
Still between two lengths?
Tell us what you grow, the space you have and your postcode. A person replies with a length and the build that suits the plot.