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SteelRoot Plot 3.14m Polycarbonate Greenhouse

A galvanised-steel arch greenhouse, 3.00 m on the ground and 3.14 m at its widest, with screw-fixed twin-wall polycarbonate.

3.00 m on the ground · 3.14 m at the widest
4–12m lengths
1.0m or 0.67m arch spacing

SteelRoot Plot 3.14 Galvanised Steel Arch Greenhouse, Twin-Wall Polycarbonate, Walk-In

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SteelRoot Plot 3.14m Polycarbonate Greenhouse

A galvanised-steel arch greenhouse, 3.00 m on the ground and 3.14 m at its widest, with screw-fixed twin-wall polycarbonate.

3.00 m on the ground · 3.14 m at the widest
4–12m lengths
1.0m or 0.67m arch spacing

01Width

02Ridge height

03Length

04Glazing

4 mm is the base specification; choose 6 mm for extra stiffness and warmth.

05Arch spacing

1.0 m is the standard spacing; choose 0.67 m for more exposed plots.

06Add-ons optional

Auto-vent windows+£99 each

Clear U-profile+£19 · 8 pieces of 2.1 m

Steel arch straps+£38 · 2 rolls of 25 m

Edge tapes and wireIn your kit: 3 items Free

SteelRoot Plot 3.14 Galvanised Steel Arch Greenhouse, Twin-Wall Polycarbonate, Walk-In

A galvanised-steel arch greenhouse, 3.00 m on the ground and 3.14 m at its widest, with screw-fixed twin-wall polycarbonate.

-£300£899

RRP: £1,199Save 25%

Delivered in 1–4 weeks from order.

Self-assembly · kerbside delivery.

Your build

Size—

Ridge height—

Glazing4 mm

Arch spacing1 m

Auto-vent windowsNone

Change size & options

Pay in 3 interest-free payments with Klarna

Email a questionEmail us

Payment🔒 Secure transaction

🚚

UK mainland deliveryFree delivery to most UK mainland postcodes. Any postcode surcharge is calculated from the delivery postcode and shown before checkout.

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Warranty termsRead what’s covered →

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14-day returnsYou pay return carriage.How returns work →

Sold by Waldenhaus LtdCompany details →

About this greenhouse

A galvanised-steel arch greenhouse, 3.00 m on the ground and 3.14 m at its widest, with screw-fixed twin-wall polycarbonate.

Structure

Frame40 × 20 mm closed steel profileGalvanised · ZAM coating (zinc-aluminium-magnesium)

GlazingTwin-wall polycarbonateScrew-fixed at every edge · 4 or 6 mm

Arch spacing1.0 m standard0.67 m close-arch option · for more exposed plots

Width3.00 m walk-inOn the ground · 3.14 m at the widest point of the arch

Included · already in the price

Ground anchorsSupplied for your buildIn the box: one at each corner, the rest along the length. On firm, level soil you need no concrete.

VentilationFront-to-back airflowTwo gable doors, each with an opening upper section, as standard

£1,199£899

Waldenhaus SteelRoot

Open the box before you buy it.
There is a lot of useful information for growers further down this page: free advice and recommendations from us.

Worth reading to the end

Your build

What exactly do I get?

Included: frame, sheets, two doors, ground anchors and fixings. Roof vents, U-profile and arch straps are optional. The base, staging and tools are yours.

SteelRoot Plot 3.14 in a garden with the door open: staging and tomatoes inside, a brick path down the middle

Will the frame feel flimsy?

40 × 20 mm closed steel profile.

One profile throughout, with ZAM coating (zinc-aluminium-magnesium). A closed box section resists twist as well as bend. The metal frame is pre-drilled and bolts together.

1.1On the pallet

What you chose in the configurator is already in this list.Add or remove upgrades right here: the price changes everywhere on the page. Tap any row for photos.

The polycarbonate

Sheets in your kit
Each sheet: 2.1 × 6 mwidth 2.1 m, length 6 m
Thickness
6 mm upgradeStiffer and warmer than 4 mm: £100Added

1.2Not on the pallet

Five things you arrange yourself.

The baseFirm soil or a level strip. Plan it belowWhat and why →
U-brackets for a hard baseOnly on concrete, paving or timberWhat and why →
Free-standing stagingFree-standing, never drilled to the frameWhat and why →
WateringA can, a hose or your own irrigation kitWhat and why →
ToolsA drill-driver and ordinary hand toolsWhat and why →

1.3Extras you can add

Three optional extras for your order. Three more come free in your kit.

Add to your order for your 4 m build

Roof vent with automatic opener

A hinged window in the roof. A wax cylinder opens and closes it: no power, no batteries.
2roof ventsThe number we recommend · £198 for two

£99 each
Clear U-profile

Clear caps that slide over the taped ends of the roof sheets and cover the tape. Sized for your 4 mm polycarbonate.

8pieces of 2.1 m16.8 m in total. One spare piece included.

£19 for the set
Ask us to add it
Steel arch straps

Steel straps fixed over the sheets along the arches, one for each arch. Optional: the greenhouse is complete without them.

2rolls of 25 m · £19 a roll50 m in total. One strap from ground to ground on each of your 5 arches.

£38 for 2 rolls
Ask us to add it

FreeIn your kit

Roof vents are added in the configurator. U-profile and arch straps are not in the basket yet: ask us and we add them to your order, support@waldenhaus.uk.

1.4What are the exact sizes and specs?Every number on this page, in one table Show

Size

Lengths: 4, 6, 8, 10 or 12 m
Width: 3.00 m on the ground3.14 m at the widest point of the arch
Ridge height: 2.02 m
Base to build: 3.2 m wideyour length plus 0.25 m

Frame

Profile: 40 × 20 mm closed steel profile0.7 mm wall
Coating: GalvanisedZAM coating (zinc-aluminium-magnesium)
Arch spacing: 1.00 m0.67 m as an option
Joints: Pre-drilled and boltednothing is welded on site

Glazing

Material: Twin-wall polycarbonateUV-stabilised
Thickness: 4 mm6 mm as an option
Sheet size: 2.1 × 6 m
Fixing: Self-drilling roofing screwswith washers, into the steel

Doors and vents

Doors: Two, one at each endthe top half of each opens on its own
Roof auto-vents: Optionalwax-cylinder opener, no power; we suggest one per 2 m of length

Ground

Firm, level soil: Ground anchors, in the boxno concrete needed
Concrete, slabs, timber: Bolt-down U-bracketsnot included

Delivery

Pallet: 1.2 × 0.8 m, about 2.3 m tall65–120 kg by length
When: Delivered in 1–4 weeks from order

By length

Length	4 m	6 m	8 m	10 m	12 m
Floor area, m²	12	18	24	30	36
Arches at 1.00 m	5	7	9	11	13
Arches at 0.67 m	7	10	13	16	19
Sheets, 2.1 × 6 m	3	4	5	6	7
Ground anchors	6	8	10	12	14

Warranty. 2-year manufacturing defect warranty on cellular polycarbonate panels + 10-year anti-corrosion warranty on the galvanised steel frame. Read the full warranty terms

Base & fixings · SteelRoot

Do I need a concrete base?

No. On firm, level soil you need no concrete.Nothing to buy

Prepare the ground first: strip the turf, then level and firm the soil. The greenhouse stands straight on it, held down by the ground anchors in your kit.

When we recommend a base

On loose, wet or sloping ground, or when you want a firmer, more permanent footing. The options are just below.

Space around it. Keep 2 m clear of fences and buildings on every side, with nothing overhanging. Where to place it

Planning permission. At 2.02 m it is under the 2.5 m limit set close to a boundary in England, Wales, Scotland and Northern Ireland. The other rules differ by nation, so height alone does not decide it. Check yours

2.1Mark out the base

Either way, start here: peg the outer line and check both diagonals.

2.3Six bases you can build

Pick one: how it is built, what fixes it down, and the six rules every base follows.

How it stands on soil

Before you build any baseSix rules. Tap one for why, with photos.

2.4Which fixings are in the box?

Ground anchors and all frame and sheet fixings are in the box. For a hard base you buy U-brackets.

In the box
For firm soil or gravel ground anchors
In the box
For the frame and sheetsEvery bolt and screwM6 bolts, nuts and washers, roofing screws and 4.2 mm screws, bagged and counted.
You buy elsewhere
For concrete, slabs or bricksU-brackets + masonry boltsA bolt-down U-bracket under every leg: the leg drops in, one bolt through both sides. Bought elsewhere: we don’t sell them yet.
You buy elsewhere
For sleepers or a timber ringU-brackets + coach screwsThe same U-bracket, coach-screwed to the sleeper; stakes pin the timber ring to the ground.

We don’t sell U-brackets yet. Any builders’ merchant or fixings supplier has them: one goes under each leg.

Ask us about your plot. Windy, wet or sloping? Send your postcode and a photo: an expert looks at your plot and tells you what we would do.

WhatsApp Email us

Wind, snow and the years

Will it stand up to the wind?

We don’t put a wind speed on it. Here is what holds it, what to add on an exposed plot, and what to check each year.

VideoThe crash testThe frame and the door under load.

The steel
40 × 20mm
Closed steel profile, 0.7 mm wall
Arch spacing
1.00 / 0.67m
Your choice of spacing
Ground anchors
6in the box
For your 4 m build

Wind and snow

What holds it when the wind gets up?

StandardIn every build

Every joint is boltedThrough pre-drilled holes. Nothing is welded on site.
Sheets screwed, not clippedEvery sheet is screwed to the steel with self-drilling roofing screws and washers: there is no clip for the wind to work loose.
Anchored to the ground6 ground anchors in the box for your 4 m build: one at each corner, the rest along the length.
Edge tapes in the kitSee the kit
Solid tape for the cut edges, breather tape for the bottom ends of the roof sheets: rain, dirt and insects stay out of the channels.

Stronger buildOn an exposed or snowy plot

Choose 0.67 m arches
2 more arches than with 1 m spacing: 7 instead of 5 on your 4 m greenhouse. More fixings along the length and shorter spans of polycarbonate.
Add steel arch straps
See the extras
Steel straps fixed over the sheets along the arches, for extra hold on exposed sites.
Choose 6 mm sheets
Heavy snow where you are? The stiffer sheet flexes less under it. We don’t put a snow load on it.

We recommend0.67 m arches with 6 mm sheets: the strongest build we make.

Materials and upkeep

Will it rust, yellow or leak?

Will the galvanised steel rust?
The frame is galvanised steel with a ZAM coating (zinc-aluminium-magnesium). Touch up a scratch to bare steel with cold-galvanising spray.
Will the sheets yellow, and how long will they last?
They are UV-stabilised, and the protected side faces the sun: the printed film marks it. Polycarbonate does age over the years, and we don’t put a lifespan on it. There is no film to re-cover.
Will it leak?
Built as the manual shows, it should not. The roof sheets run whole over the arch, with no joint across the slope; every screw has a washer and goes in straight; the sheet ends are taped. Condensation on a cold morning is normal: the breather tape lets it drain.
What upkeep does it need?
Walk round it once a year, as the warranty asks: anchors firm, screws snug, tape sealed. No routine painting and nothing to re-treat.

The warranty, said before you pay. 2-year manufacturing defect warranty on cellular polycarbonate panels + 10-year anti-corrosion warranty on the galvanised steel frame. Damage from sustained wind above 50 mph or any Met Office Named Storm is not covered, and an unanchored greenhouse is not covered for structural failure. Read the warranty

Assembly

Can we build it ourselves?

Two adults, a dry weekend and ordinary tools. The manual is free and in full: read it before you order, not on the day.

Roof sheets going on over the arches of a Plot 3.14

The build in numbers

Bolts, screws, one sheet to cut

The galvanised steel frame bolts together, self-drilling screws hold every sheet, and you cut only the two end walls. Base ready before you start.

Open the assembly manual Ask about a step

Ask us anything; an expert answers.

Cordless drill driving a roofing screw through the polycarbonate into the arch

Tools · nothing special Cordless drill · spanner · PH2 driver · spirit level · sharp knife or fine‑tooth jigsaw · spade You never weld or cut the steel. The manual lists one spanner size (M8).

Is it hard to build?No puzzle: the frame bolts together, the sheets screw on, and only the two end walls are cut. Every part has a code and every step is drawn; the whole build is on video.
What do we save by building it?Save£400–£600That is about what sellers charge to fit a steel greenhouse of this size. Two of you and a dry weekend keep it.Fitting prices published by UK sellers, September 2026.
Who builds it if we can’t?It takes two people: the roof sheets are 6 m long. If that is not you, any local handyman or fencing contractor can build it from the manual. We don’t fit greenhouses. Send them the manual before they quote.
Before the first boltRead the manual to the end: the base and the anchors come before any panel. Check the pallet against the packing list within 14 days of delivery. Anything short or damaged? Tell us before you start and we send it free. A storm on the way? Don’t start on the polycarbonate unless you can finish before it arrives.

4.1The build in six short steps

From marking out to the last sheet. Tap a step for its photos and details.

Step 1 of 6Mark out and levelPeg the outer line, check the diagonals, level the ground.Photos and details →
Step 2 of 6Bolt the arches togetherPre-drilled: arches, crossbars and end frames bolt together.Photos and details →
Step 3 of 6Anchor it as it goes upAn anchor in each leg the manual marks: one screw, buried firm.Photos and details →
Step 4 of 6 · the only cuttingCut the two end wallsDraw round the end frame on the last sheet and cut.Photos and details →
Step 5 of 6End walls on, doors hungScrew the end walls on, tape their cut edges, hang the doors.Photos and details →
Step 6 of 6Roof sheets, then the tapesWhole 2.1 × 6 m sheets over the arches: no cutting. Then tape their ends.Photos and details →

4.2Is cutting the polycarbonate hard?

The end wall is the template: you never measure a curve.

No. Only one sheet is cut: the one for the two end walls. The roof sheets go on whole: nothing to cut.

Roof: no cutting

Large piece: the door and one side
Small piece: the other side

Each end wall takes two pieces: a large one for the door and one side, a small one for the other side. All four come out of the last sheet.

Mark from the frame, cut a little outsideLay the last sheet flat, printed side up. Lay an assembled end wall on it and mark round the arch. One sheet gives all four pieces: for each end, a large one (the door and one side) and a small one.
Screw it on, then trim to the archWith the end wall flat on the ground, fix the piece with the roofing screws. Then run the knife along the arch and the spare comes away.
Cut round the doors lastThe two door sections are screwed under the same piece. Cut along the gaps round them and both halves open: there is no door to measure.

On a real build

What keeps the sheet whole

Channels run top to bottomOn the finished wall, never sideways.
Check before each cutHold the piece in its place, printed side out. A piece cut mirror-wise cannot be turned over.
A new blade, light passesScore along a straight edge several times; a fine-tooth jigsaw for the curve.
Film on until it is fixedMark on the film and cut through it. Peel it as soon as the sheet is screwed down.
Tape each cut edge straight awaySolid tape on the cut edges before the roof sheets go on; breather tape on the bottom ends.
A slip is not the endAny UK plastics supplier stocks the same clear twin-wall sheet, and we check your sizes.

How the sheets are fixed

A self-drilling roofing screw with its washer, through the sheet into the arch

Self-drilling screws, placed by eyeRoofing screws with washers cut their own hole through the sheet into the steel. Space them by eye along each arch: nothing to mark out, nothing to pre-drill.

Two hinges on the door post of a Plot 3.14, one for each half of the door

Door hinges, set by eyeHold each door leaf level in its frame, then screw the hinges on where it sits right.

Delivery

How does it get to my kerb, and when?

One pallet on a tail-lift lorry, delivered in 1–4 weeks from order. Free to most of the UK mainland; Northern Ireland, the Highlands and the islands at a set surcharge.

1–4weeks to your kerb

Ready at the factoryFor most sizes the factory picks your parts onto a pallet and sends it.
Made firstIf your size or options are not ready, the factory makes them, then they go straight onto the pallet.
The date, in writingAn “In production” email, usually within 5 working days. Then we agree the delivery day with you, and move it if you can’t be in.

Step 1Picked at the factoryEvery part for your size and options, with the packing list.
Step 2Bundled and labelledArches and bars bundled, fixings boxed with labels, so every part can be checked against the list.
Step 3To your kerbA tail-lift drop at the kerb. Check it against the packing list and photograph any damage.

One pallet, strapped, about 2.3 m tall

One pallet for every length. The tail-lift lowers it at the kerb or on the driveway: firm, level ground a pallet truck can roll on. A pallet truck will not cross grass or gravel.

the pallet: 1.2 × 0.8 m
tall, sheets upright: about 2.3 m
by length: 65–120 kg

Who moves it from the kerb to the garden?

The driver sets the pallet down and does not carry it into the garden. From there the kit goes to the site by hand, as bundles and sheets. Gateways, steps and a tight side passage are what catch people out, not the lorry.

Tell us about access with your order number: gate width, a single-track lane, a steep drive, low cables, a soft verge. It goes to the carrier with the booking.

Email your access notes

From the lorry to the spot: tail-lift at the kerb, then the gate and the path by hand.

Nothing more to pay at the door. Import duty, VAT and customs clearance are in the price: the greenhouse comes from the European Union and we are the importer.What the price covers

Delivery

Do you deliver to my postcode?

Free to most of the UK mainland. Northern Ireland, the Highlands and the islands carry a set surcharge, because the pallet network charges us for them. Check your postcode: the figure shown is the one checkout uses.

All delivery zones

UK mainlandFree
Isle of Wight£49
Scottish Highlands£79
Northern Ireland£99
Scottish Islands£149
Isle of ManContact us before ordering
Channel Islands, Isles of Scilly, BFPONot served

Parts & warranty

What if something is missing, damaged or breaks?

Four things that can go wrong, and what happens next.

The warranty, in one line2-year manufacturing defect warranty on cellular polycarbonate panels + 10-year anti-corrosion warranty on the galvanised steel frame.

Read the full warranty terms

Missing or damaged on arrivalWe send it free, delivery paidEvery kit is picked against its packing list at the factory. If a part is still short or damaged, write “damaged” on the delivery note, check the list within 14 days, photograph it and email us.
You need a part laterParts held for ten yearsEmail the part code, a photo and your order number. You pay cost plus carriage, confirmed first. We don’t post single polycarbonate sheets as spares: any UK plastics supplier cuts the same twin-wall, and we check your sizes. A panel with a manufacturing defect is sent under the warranty.
Warranty claimAcknowledged in 2 days, decided in 7Send a photo and your order number. Replacements within 14 working days. The part is free; you pay the delivery. Damage from sustained wind above 50 mph or any Met Office Named Storm is not covered.
You change your mind14 days from deliveryUnused, unassembled and in the original packaging. You arrange and pay for the return pallet, typically £150–£250 on the mainland. Stuck on something in the build? Talk to us first.How returns work →

Finished install · end gableFinished SteelRoot 3.14m install · end-gable view in customer garden.
Interior · arch rowReal SteelRoot 3.14m install · interior view down arch row.
Interior · growing rowsTwo full growing rows plus working path inside SteelRoot 3.14m.
Interior · raised bedsSteelRoot 3.14 m interior · raised beds, working path, full headroom.
Interior · tomatoes in seasonTwo raised beds plus brick working path · full 2.02 m ridge headroom inside the 3.14 m envelope.
Customer install · gravel baseSet square on a gravel hardstanding.
Illustration · gravel baseOur Plot 3.14 on a gravel base. The garden is an illustration.

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Not sure which length?

Which length do I need, and what does it cost?

All five stand on the same 3.00 m. Choose by what you grow, then check the space you have.

The five lengths, drawn to one scale. Inside each: growing beds and a path between the doors.

4 mS · 10 × 13 ft
12 m² floorTomatoes, salad and seedlings
Save £300£899~~RRP £1,199~~
Choose this size
6 mMost popularM · 10 × 20 ft
18 m² floorTwo long beds of salad and tomatoes
Save £250£1,099~~RRP £1,349~~
Choose this size
8 mL · 10 × 26 ft
24 m² floorMost of our veg under one roof
Save £250£1,299~~RRP £1,549~~
Choose this size
10 mXL · 10 × 33 ft
30 m² floorA serious kitchen garden
Save £150£1,599~~RRP £1,749~~
Choose this size
12 mXXL · 10 × 39 ft
36 m² floorGrowing to sell
Save £150£1,799~~RRP £1,949~~
Choose this size

Prices are for 4 mm sheets and 1.00 m arch spacing. Free delivery to most UK mainland postcodes; any postcode surcharge is shown before checkout.

Between two lengths? Take the longer one.The step up is £200–£300: small money next to rebuilding later. Need more than 12 m? It extends in 2 m sections to any length, made to order: ask us for the price.
Measure before you choose.The base is 3.2 m wide and your length plus 0.25 m. The manual asks for 2 m clear of fences and buildings.
Wind and snow change the build, not the length.On an exposed or snowy plot choose 0.67 m arches and 6 mm sheets: the strongest build we make.
0.67 m arches+£50
6 mm sheets+£100

Not sure which length? The calculator asks three questions and one measurement, then gives you a length, the reason for it and the space it needs.

Work out my length

The sizing guide Ask us

Ours SteelRoot

Alternative Entry-tier aluminium

Alternative Polythene polytunnel

01 Frame

40 × 20 mm closed steel profile, galvanised

Aluminium sections: check the profile

Steel hoops under film

02 Glazing

4 or 6 mm twin-wall polycarbonate, UV-stabilised

Glass or polycarbonate: check the thickness

Single-skin polythene film

03 Arch spacing

1 m standard · 0.67 m option for exposed plots

Check the model

Check the hoop spacing

04 Panel fixing

Self-drilling roofing screws at every edge

Clips or screws: check the fixing method

Film tensioned over hoops

05 Anchoring

Ground anchors in the box · no concrete on firm soil

Check the model

06 Warranty

2-year manufacturing defect warranty on cellular polycarbonate panels + 10-year anti-corrosion warranty on the galvanised steel frame

Varies by brand

Varies by maker

07 Replacement cycle

No film to re-cover: rigid panels, screwed in

Depends on how the panels are fixed

Check the rated life of the film

The other two columns list what to check, not a verdict on any brand: compare against the product you are looking at.

Is it worth the money?

Why pay this much instead of a polytunnel?

Film is cheaper on the day and glass looks the part. This is what the price buys, and what it doesn’t.

Or a film polytunnel?Film costs less on the day, and the cover is replaced every few years. Here rigid sheets are screwed to a steel frame: nothing to tension, nothing to re-cover. If the lowest first price matters most, film is the better buy.
Or an entry-tier aluminium greenhouse?Compare the frame section, how the panels are fixed and what anchors it, not the starting price. Here: 40 × 20 mm closed steel profile, sheets screwed on, ground anchors in the box.
Or a used one?Cheap or free, and then the work starts. What people who have done it report:
- Taking it down. Seized bolts and rusted clips; a day or more in someone else’s garden.
- Getting it home. Van hire, and panes that break on the way.
- Building it again. No manual and no part numbers.
- Filling the gaps. Missing glass, clips and bolts are yours to find and pay for.
New means fresh galvanising and new sheets, every part with its manual, a written warranty, parts held for ten years, and delivery to your kerb.
Or build your own?It can cost less on the day. What people who have built their own report:
- The design is on you. A frame that is not sound can go over in a winter gale.
- The glazing is the cost. Glass or polycarbonate is not cheap bought on its own.
- Every fitting is a shopping trip. A kit has its screws, clips and seals counted; you buy them one by one.
- It wears you down. Builders say the enthusiasm goes long before the job is done.
Here you buy a frame drawn for this span, ground anchors made for it, a manual, parts held for ten years and a written warranty.

The price, the payment, the company

What do I pay, and who am I paying?

The price includes VAT and import charges. Delivery is free to most UK mainland postcodes; Northern Ireland, the Highlands and the islands add a set surcharge, shown before checkout.

Who am I paying?

Waldenhaus Limited, 71-75 Shelton Street, London WC2H 9JQ. Company No. 16877766, registered in England and Wales on 27 November 2025. VAT GB519957245.

We are new, and you should check us: it takes a minute at Companies House. We have no showroom; you get the full manual and the base plan before you buy, the assembly on video, and an expert who answers.

Look us up at Companies House Why Waldenhaus Read the warranty

An expert answers

We answer before you order, and after you pay

On WhatsApp, by email, or we call you back. After you pay it is the same people, until the pallet is at your kerb and after it.

WhatsApp Email us

Prefer we put the order together? Send the length, glazing, arch spacing and extras you want and we send a payment link with it all set.

Is there anything to pay at the door?
No. The greenhouse comes from the European Union and we are the importer: duty, VAT and customs clearance are done and in the price. A VAT invoice on request.
Can I pay in instalments?
Where Klarna offers it for your order, its pay-in-3 terms are shown beside the price and again at checkout; the amounts and approval are Klarna’s. Card payments go through Shopify’s secure checkout: we never see your card number. A school, a council or a company? Ask us for a formal quotation.
Is it safe to pay before it arrives?
You pay at order for a delivery in 1–4 weeks, not months. Until our “In production” email, usually within 5 working days, you can cancel free of charge. Card and Klarna payments carry their provider’s protection, and your rights under the Consumer Rights Act apply. After you pay, the same people answer: WhatsApp, email or a call back.

What does the price include?In the price · your choice · yours to arrangeShowHide

In the price

The whole kit on one palletFrame, sheets, both doors, every bolt and screw
4 mm sheets, 1.00 m archesThe standard build. Upgrades are your choice
Ground anchorsFor firm soil, counted for your length
Delivery to your kerbTail-lift lorry, UK mainland
Import duty, VAT and customsIt comes from the EU; we are the importer
The manual and your base planFree, in full, before you buy

Your choice, priced on this page

6 mm sheetsStiffer and warmer; 4 mm is the standard
+£100
0.67 m arch spacingFor an exposed or snowy plot
+£50
Roof ventsWith automatic openers
£99 each
Clear U-profileClear caps over the taped sheet ends
from £19
Steel arch strapsOver the sheets along the arches, for exposed sites
£19 a roll
A postcode surchargeOnly Northern Ireland, the Highlands and the islands

Yours to arrange

A firm, level baseSoil costs a weekend; slabs or concrete are a local quote
U-bracketsOnly if the base is hard. Bought elsewhere: we don’t sell them yet
StagingFree-standing units only; never drill the frame
WateringA can, a hose or your own irrigation kit
A builderOnly if you would rather not build it yourself

We publish no prices for what we don’t sell.

The factory

Who actually makes it?

A full-size factory in the European Union makes it, and you buy it first-hand: we are the importer, with no wholesaler or marketplace seller in between.

A factory, not a warehouse of boxes
The arches and frames in these pictures are made on this floor.
First-hand, no middlemen
We are the importer. Nobody else stands between the factory and your garden.
Packed and sent from the factory
Your kit is picked against its packing list there and leaves on its own pallet.
Parts from the source
Spare parts come from the same factory, held for ten years from purchase.

Before you order

Is it the right greenhouse for me?

The questions buyers ask us most, each with a short answer and the tool or guide that settles it.

Which length should I take?
Between two lengths, take the longer one: the step up is small next to rebuilding later. Three questions and one measurement give you a length and the space it needs.
Find my length The sizing guide
Will it fit my garden?
It stands on 3.00 m. The base is 3.2 m wide and your length plus 0.25 m, and the manual asks for 2 m clear of fences and buildings.
Your base plan Where to place it
Do I need planning permission?
It depends on the property and on where the greenhouse stands; height alone does not decide it. The checker takes two minutes; your planning authority has the last word.
Open the checker The rules, explained
Can I put it on an allotment?
Ask your site first: rules differ on size, glazing and bases, and some sites allow one kind of structure and not another. In its favour, it needs no concrete: on firm, level soil the anchors in the box hold it.
Sizes for your site Send us your site’s rules
Which model suits my plot?
Tell us your postcode, how exposed the plot is and the space you have. An expert replies with the model, length and arch spacing that fit, and where you needn’t spend more.
Email us Request a callback
4 mm or 6 mm polycarbonate?
4 mm is the standard and the lowest price. 6 mm has larger cells and thicker walls:
- Stiffer: it flexes less between the arches.
- Warmer: it holds more heat.
- Tougher: more body against hail and falling debris.
Take 6 mm for heavy snow or winter growing.
Choose the glazing Polycarbonate vs glass
Can I grow through the winter?
6 mm sheets hold more heat than 4 mm. We don’t supply heaters yet. The guide covers how growers heat a polycarbonate house through a British winter.
The winter heating guide
How does it look in a garden?
A low steel arch under clear sheets, 2.02 m at the ridge. Judge the shape for yourself in photos from real gardens.
See it in real gardens
When is the right time to buy?
There is no season to wait for. It is delivered in 1–4 weeks from order, so order once the base is planned. Autumn and winter are the time to lay it, ready for spring.
The growing calendar

Read before you order

5 stars: 13 (100%)
4 stars: 0 (0%)
3 stars: 0 (0%)
2 stars: 0 (0%)
1 star: 0 (0%)

Wanted something that wouldn't look like an eyesore at the bottom of the garden. This actually fits in nicely, clean lines, not some flimsy thing. I've got tomatoes, cucumbers, and chillies all doing well. The light transmission is brilliant. Only wish I'd gone for the 0.67m spacing given how exposed our plot is.

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Looks like its always been part of the garden. The pine weathers nicely, already got a bit of colour to it. Turned out way better than I thought it would.

Looked at a few brands before settling on this one. Glad I went with it. The joints feel solid, no rattles, no gaps. Im out there most mornings with a coffee now.

Scottish weather doesnt mess about. I honestly thought this would be flat on its side by March. Hasnt moved a millimetre. Warmer inside than I expected too.

Were in it every single day. Salads, herbs, brassicas, you name it. The light is brilliant and it sailed through winter without any fuss. Great bit of kit.

My old one from the DIY shop used to rattle like crazy whenever the wind picked up. This doesnt budge at all. That thicker frame makes a real difference. Worth paying a bit extra.

Great customer service. Top notch!

Bit nervous ordering something this big online, not gonna lie. But it arrived fine, everything was labelled, went up without any hassle. Not had a single leak and Kents been throwing it down lately.

So solid. Very pleased!

It actually looks decent in the garden, not like one of those plastic monstrosities. The tomatoes and peppers are going mental in there. Stays warm, feels sturdy. Not a single complaint.

Dead easy to build! Much stronger than the cheap plastic ones
Tomatoes are growing

I had a cheaper one before and it didnt even make it through two winters. This is completely different. Solid frame, no flex at all. Properly built, looks like it'll last.

What else do buyers ask?

How does it ventilate in summer?

A stable door at each end: the top half opens on its own, so air crosses the greenhouse from end to end. Roof auto-vents are optional, £99 each; we recommend one per 2 m of length. Changed your mind after paying? If the order hasn’t left the factory, we add a vent to the same pallet. See the roof vents →

Will I need planning permission?

It depends on the property and on where the greenhouse stands; height alone does not decide it. The rules differ in England, Wales, Scotland and Northern Ireland: our checker takes you through yours and links to the official guidance. Listed, in a conservation area or under other restrictions? Ask your local planning authority before you build.

How long does the build take?

Two adults, a dry weekend and ordinary tools. The frame is pre-drilled and bolts together; nothing is welded. The one job that takes care is cutting the polycarbonate for the two end walls. We don’t offer an assembly service. See the build, step by step →

What does a return cost?

You have 14 days from delivery to return it unused, unassembled and in the original packaging. You arrange and pay for the return pallet, typically £150–£250 on the mainland. Full terms in our refund policy. See returns, parts and warranty →

Can I pay monthly?

Where Klarna offers it for your order, its pay-in-3 terms are shown beside the price and again at checkout; the amounts and approval are Klarna’s. See what you pay →

Is it a polycarbonate tunnel greenhouse?

SteelRoot is the Waldenhaus galvanised steel arch greenhouse for growers who want a larger, practical structure without a film-cover replacement cycle. The frame uses 40 × 20 mm RHS galvanised steel with ZAM coating (zinc-aluminium-magnesium), screw-fixed twin-wall polycarbonate and a modular arched form for serious growing space.

To compare lengths and options, see the SteelRoot range. Weighing up a polytunnel? Read our polytunnel vs polycarbonate greenhouse guide.

Common questions

Is SteelRoot an arched polycarbonate greenhouse?: Yes. It is an arched greenhouse clad in twin-wall polycarbonate, designed as a more permanent alternative to a film polytunnel for UK gardens and growing plots.
Is it a galvanised steel greenhouse?: Yes. The frame is galvanised steel with ZAM coating (zinc-aluminium-magnesium).
Is 6 mm polycarbonate standard?: No. SteelRoot uses 4 mm twin-wall polycarbonate as standard, with 6 mm available as a glazing option.

SteelRoot Plot 3.14m Polycarbonate Greenhouse

About this greenhouse

What exactly do I get?

40 × 20 mm closed steel profile.

1.1On the pallet

1.2Not on the pallet

1.3Extras you can add

Roof vent with automatic opener

Clear U-profile

Steel arch straps

Size

Frame

Glazing

Doors and vents

Ground

Delivery

By length

Do I need a concrete base?

2.1Mark out the base

2.2Six rules before you dig

2.3Six bases you can build

2.4Which fixings are in the box?

Will it stand up to the wind?

Closed steel profile, 0.7 mm wall

Your choice of spacing

For your 4 m build

What holds it when the wind gets up?

Will it rust, yellow or leak?

Will the galvanised steel rust?

Will the sheets yellow, and how long will they last?

Will it leak?

What upkeep does it need?

Can we build it ourselves?

Bolts, screws, one sheet to cut

4.1The build in six short steps

4.2Is cutting the polycarbonate hard?

How does it get to my kerb, and when?

One pallet, strapped, about 2.3 m tall

Who moves it from the kerb to the garden?

Do you deliver to my postcode?

What if something is missing, damaged or breaks?

Which length do I need, and what does it cost?

Why pay this much instead of a polytunnel?

What do I pay, and who am I paying?

Who am I paying?

We answer before you order, and after you pay

Is there anything to pay at the door?

Can I pay in instalments?

Is it safe to pay before it arrives?

In the price

Your choice, priced on this page

Yours to arrange

Who actually makes it?

A factory, not a warehouse of boxes

First-hand, no middlemen

Packed and sent from the factory

Parts from the source

Is it the right greenhouse for me?

Which length should I take?

Will it fit my garden?

Do I need planning permission?

Can I put it on an allotment?

Which model suits my plot?

4 mm or 6 mm polycarbonate?

Can I grow through the winter?

How does it look in a garden?

When is the right time to buy?

What else do buyers ask?

Is it a polycarbonate tunnel greenhouse?

Common questions