8×20 Wooden Greenhouse — NORDIC-XXL from £1,899
By the Waldenhaus founder team · Last updated: May 2026
8×20 ft is the largest wooden greenhouse we make — and the size that puts you into "walk-in / market grower" territory. Two parallel ground beds for vine crops, a third growing zone for seedlings or year-round salads, plus dedicated workbench and tool storage. Nearly 15 m² of growing surface — roughly the floor area of a small UK kitchen.
NORDIC-XXL from £1,899 is the NORDIC range flagship. Same Swedish pine from sustainably-managed forests, same 1.2 mm galvanised steel joints, same screw-fixed CrystalLight panels as the £1,499 NORDIC-S — at the size that justifies a serious garden.
Who needs an 8×20 ft greenhouse?
The customer profile in our pre-sales:
The serious market-scale grower. Allotment-society veg sales, farmers' market microgreens, professional cut-flower production. NORDIC-XXL gives you ~15 m² of structured growing space — enough to run multiple commercial micro-crops without spilling into outdoor work.
The "complete garden architecture" buyer. You're designing a permanent garden destination — kitchen garden + walk-in greenhouse + maybe a sauna pod and garden office. NORDIC-XXL's footprint (8×20 ft = 2.4 × 6.1 m) is the size that anchors a serious garden plan.
The two-grower household. You and your partner both grow seriously, and 11.9 m² of NORDIC-XL doesn't quite split. NORDIC-XXL gives you two distinct working zones without stepping on each other.
The "walk-in greenhouse" searcher. "Walk-in" usually means: tall enough to stand inside without ducking, wide enough to push a wheelbarrow through, long enough to walk meaningfully. NORDIC-XXL hits all three — 1.85 m eaves, 0.7 m central path, 6.1 m walking length.
The 20×8 / 20ft greenhouse buyer. Same product as 8×20. UK manufacturers vary on which dimension comes first — NORDIC-XXL is 8 ft wide (door wall) × 20 ft long.
Real 8×20 ft layout — what fits inside
Internal area: ~14.9 m².
Three-zone walk-in layout (most popular):
- Front zone (door + 4 m of length): two staging benches face-to-face for spring seedlings — 4 benches × 0.6 m × 2 m
- Middle zone (next 4 m): two parallel ground beds (1.0 m wide each), 0.5 m central path, vine crops on canes to apex
- Back zone (final 4 m): workbench corner + tool wall + cold-storage shelf for off-season tubers and bulbs
Two-ground-bed + dedicated seedling layout:
- Two parallel ground beds full length (each 6 m × 1.0 m) for indeterminate tomatoes and cucumbers
- Door-end working zone (1 m of length × full width) for benches and tools
- Cane structure on each bed reaching to the apex for vine crops
Market-grower layout (commercial):
- Three growing rows down the length (each 6 m × 0.5 m) for cut flowers or microgreens
- Two narrow paths (0.4 m each) — adequate for trolley access
- Door-end pack-out station (1 m × full width)
Real annual output a NORDIC-XXL owner reports:
- 30-40 cordon tomato plants (mix indeterminate / bush)
- 12-20 pepper / chilli plants
- 8-12 cucumber vines + 3-5 melons
- 600+ seedling trays in spring
- Year-round herbs, brassicas, winter salads
- Cut flowers (commercial-scale): 200-400 stems / week in season
- Microgreens (commercial-scale): 6-10 trays / week
You can have two adults working independently in NORDIC-XXL. The greenhouse becomes a place you spend hours in, not a structure you visit briefly.
NORDIC-XXL specs
| Spec | Value |
|---|---|
| Footprint | 8 ft × 20 ft (2.43 m × 6.10 m) |
| Internal area | ~14.9 m² |
| Eaves height | 1.85 m |
| Apex height | 2.25 m |
| Door | 0.7 m × 1.85 m double-hinged |
| Glazing | 4 mm CrystalLight twin-wall polycarbonate, screw-fixed |
| Frame | 45×45 mm Swedish pine from sustainably-managed forests + 1.2 mm galvanised steel at every joint |
| Roof vents | 4 manual (SmartVent auto-vent available, +£60 each) |
| Anchor system | Heavy-duty Ground Anchors (no concrete pad required) |
| Weight (kit) | ~190 kg |
| Price | from £1,899 |
| Free UK Mainland delivery | 5–14 days |
| Warranty | 10-year anti-rot frame + 5-year polycarbonate |
→ Full product page: Waldenhaus NORDIC Greenhouse
How 8×20 compares to other NORDIC sizes
| Size | Internal area | vs NORDIC-XXL | Best for | Price |
|---|---|---|---|---|
| NORDIC-S 8×6 | 4.5 m² | -70% area, -£400 | Patio / starter | £1,499 |
| NORDIC-M 8×10 | 7.5 m² | -50% area, -£300 | Family veg | £1,599 |
| NORDIC-L 8×13 | 9.7 m² | -35% area, -£200 | Serious grower | £1,699 |
| NORDIC-XL 8×16 | 11.9 m² | -20% area, -£100 | Year-round multi-crop | £1,799 |
| NORDIC-XXL 8×20 | 14.9 m² | baseline | Walk-in / market | £1,899 |
The "NORDIC-XL vs NORDIC-XXL" decision: XL gives you proper two-ground-bed configuration; XXL gives you XL plus significant additional capacity (third zone for seedlings/workbench). The £100 step rewards itself if you'll genuinely use the extra 3 m².
Materials and engineering
NORDIC-XXL is the largest in the range — and engineered to handle the additional structural loads:
- 45×45 mm Swedish pine from sustainably-managed forests frame — same cross-section as smaller sizes (over-engineered at this scale; we don't downgrade for the larger model)
- 1.2 mm galvanised steel at every joint — over-engineered for 8×20 ft wind loads
- Screw-fixed 4 mm CrystalLight polycarbonate — continuous wrap, no horizontal eaves seam (critical at 6 m roof span)
- Heavy-duty Ground Anchors — properly distributed along the long walls for storm-load distribution
- Co-extruded UV layer — 10-year no-yellowing warranty (matters more on the larger glazed surface)
- 4 roof vents — distributed along the 20 ft length to prevent hot zones in summer
For storm engineering at this scale: Storm-Resistant Greenhouse — UK Engineering Notes.
For ventilation at this size: SmartVent auto-vents are strongly recommended — 4 of them at +£60 each (£240 total) saves the daily summer venting routine and prevents tomato-blight-from-heat-stress problems.
Assembly: weekend + Saturday afternoon, 2 adults
NORDIC-XXL is the largest assembly in the range. Customer reports: two adults, Saturday + Sunday + Saturday-after if taking it slow, or one full Saturday + full Sunday for fast experienced builders. Typically 14-18 working hours.
The main difference vs smaller sizes:
- More glazing panels (~30% more than NORDIC-XL)
- Roof panels at 6 m length need careful handling — recommend 3 people for the apex installation (not 2)
- Frame timber count goes up by ~30% vs NORDIC-XL
Tools: cordless drill, spirit level, step-ladder (essential, full height), two 13 mm spanners, strongly consider scaffold tower or two step-ladders for the apex roof work at this size.
→ Full walkthrough: Greenhouse Assembly Guide.
Pricing & delivery
- NORDIC-XXL 8×20 ft: from £1,899
- Free UK Mainland delivery in 5–14 days (carrier will require a flat dropping point — 6 m timber bundles aren't manhandleable solo)
- 14-day returns from delivery
- Warranty: 10-year anti-rot frame + 5-year polycarbonate
Optional add-ons (recommended at this size):
- 4× SmartVent auto-vents: +£240 (essentially required for summer if you're not home daily)
- Highlands/islands surcharge: quoted at order
- Professional installation: £500-£900 if you'd rather not self-assemble at this scale
→ Full FAQ: /pages/faq
Frequently asked questions
Is 8×20 the same as 20×8?
Yes. UK manufacturers vary in which dimension comes first. NORDIC-XXL is 8 ft wide (door wall) × 20 ft long.
Is NORDIC-XXL a true "walk-in" greenhouse?
Yes. 1.85 m eaves give standing clearance for most adults. 0.7 m central path is wide enough for two adults to pass or for a wheelbarrow. 6.1 m length gives meaningful walking distance.
Is 14.9 m² enough for a market-grower business?
For light commercial use (£5-15K/year revenue from a single greenhouse): yes. For full commercial scale, you'd typically run multiple NORDIC-XXLs in parallel.
How many roof vents does NORDIC-XXL come with?
Four manual vents distributed along the 20 ft apex. We strongly recommend upgrading to SmartVent auto-vents at this size — at £60 each, four of them at £240 saves the daily summer venting routine.
Can two people assemble NORDIC-XXL?
Yes, but the apex roof installation is much easier with three. Customer reports: Saturday + Sunday + Saturday-after for a relaxed pace, or full Saturday + Sunday for experienced fast builders.
Do I need a concrete base for NORDIC-XXL at this size?
Not for storm-resistance — Heavy-duty Ground Anchors are properly distributed along the long walls. Concrete is fine if you want permanence; for serious commercial use, paving slabs on hardcore (better drainage) is the most common base.
How long does NORDIC-XXL last?
Same as the rest of the range: 20-30 years with maintenance (re-treat timber every 2-3 years). Polycarbonate panels last 15-20 years before UV haze becomes noticeable.
What's the maximum wind it'll survive?
Engineered for British storm conditions: 1.2 mm steel joints + screw-fixed panels + Heavy-duty Ground Anchors will hold to 80+ mph gusts when properly anchored. We don't claim "heavy-duty" — we describe construction. For sites with consistent gust exposure (coastal, exposed hillside), consider supplementing with a windbreak hedge.
Should I buy NORDIC-XXL or two NORDIC-Ms?
For scale: one NORDIC-XXL gives you 14.9 m² + workflow continuity. Two NORDIC-Ms give you 15 m² + duplication of door, ventilation, frame footprint. NORDIC-XXL is the right answer for almost everyone unless your garden has two distinct sunny spots.
Explore the NORDIC range
→ Shop NORDIC-XXL 8×20: Product page
→ Compare all five sizes: /collections/nordic · /pages/catalog
→ Hub: Wooden Greenhouses: /pages/wooden-greenhouses
→ Buying framework: /pages/buying-guide
→ Other sizes: 8×6 · 8×10 · 8×13 · 8×16
Last updated: May 2026