Leviathan Wooden Pergola 6m x 3m | 120mm Posts | Smart Seal Treated | Nationwide Installation Included

Leviathan Wooden Pergola – 6m x 3m | 120mm Posts | Smart Seal Timber Treatment

Six metres. That’s not a garden feature — that’s a statement. The Leviathan Wooden Pergola 6m x 3m by Dunster House is the most expansive freestanding pergola in the entire Leviathan range, and it transforms outdoor spaces in a way that nothing else can match. At full six metres wide and three metres deep, this structure doesn’t just enhance your garden — it becomes the defining architectural element of your entire outdoor space.

Think of what six metres makes possible. A full-length covered veranda running along the rear of your home. A dedicated outdoor dining room at one end and a fully equipped lounge at the other, with a bar or outdoor kitchen in between. A sheltered entertaining space large enough to host a party regardless of the British weather. The 6m x 3m Leviathan is the pergola for those who entertain seriously, garden ambitiously, and refuse to compromise on scale.

Built by Dunster House from slow-grown, pressure treated spruce — not cheap pine — with every rafter pre-cut, pre-notched, and planed to precision. The commanding 120mm x 120mm upright posts provide the structural integrity to carry this span with complete confidence, while the Smart Seal timber sealant finish, applied as standard, delivers a superior protective barrier against moisture, UV damage, and the relentless British weather. Backed by a 10-year guarantee against rot and insect infestation.

🌟 Professional nationwide installation and Smart Seal timber treatment are both included in the price, free of charge. Our experienced fitting teams cover the whole of Mainland UK — handling everything from delivery to final fitting on this substantial structure, so you can simply step outside and enjoy.

Key Features

• ✅ Extraordinary 6m x 3m footprint — the largest Leviathan freestanding pergola, for those who think big
• ✅ Imposing 120mm x 120mm upright posts — the structural strength to carry a full 6m span with confidence
• ✅ Slow-grown spruce, not cheap pine — denser grain, superior long-term durability
• ✅ Fully pressure treated (not dip treated) — long-term rot and insect resistance
• ✅ Smart Seal timber treatment included as standard — superior moisture and UV protection
• ✅ 10-year guarantee against rot and insect infestation
• ✅ Pre-notched, pre-cut, planed rafters — precision engineered for a clean, professional finish
• ✅ All fixings included — no hidden extras
• ✅ Ideal as a full-length veranda — 6m of covered outdoor space along the rear of your home
• ✅ Spectacular for climbing plants — 6m of rafter span creates an unrivalled living canopy
• ✅ Nationwide installation included as standard — anywhere across Mainland UK, free of charge

Specifications

• Approximate Size: W6m x D3m (W19'8" x D9'10")
• Upright Posts: 120mm x 120mm
• Timber: Slow Grown Spruce (Fully Pressure Treated)
• Timber Finish: Smart Seal (included as standard)
• Guarantee: 10 Years against Rot and Insect Infestation
• All sizes quoted are nominal. All fixings supplied. Rafters are pre-cut, pre-notched, and planed.

Why Choose Bespoke Oak and Slate?

At Bespoke Oak and Slate, we supply and install premium Dunster House garden structures across the UK. A structure of this scale demands professional installation — and that’s exactly what you get, included as standard and free of charge, anywhere across Mainland UK. No hidden costs, no surprises — just an expertly installed, fully Smart Sealed pergola ready for you to enjoy.

Frequently Asked Questions

Is the 6m x 3m the largest Leviathan pergola available?

Yes — the Leviathan 6m x 3m is the largest freestanding pergola in the entire Leviathan range. At six metres wide, it offers an unmatched covered outdoor space and is the ultimate choice for serious entertainers, large gardens, and those wanting a full-length veranda-style structure.

Does the price include installation?

Yes — professional nationwide installation is included in the price, free of charge. Given the scale of this structure, professional installation is essential — and our experienced fitting teams handle everything from delivery to final fitting, anywhere across Mainland UK.

What is Smart Seal and is it included?

Smart Seal is a premium timber sealant that provides a superior protective barrier against moisture penetration, UV damage, and weathering — going beyond standard pressure treatment to keep your pergola performing at its best for longer. Smart Seal is applied as standard with every order, free of charge, by our installation team as part of the fitting process.

Do you install anywhere in the UK?

Yes. We install anywhere across Mainland UK at no extra cost. Whether you’re in the South West, the Midlands, Scotland, or anywhere in between — our teams will come to you, regardless of the size of the structure.

Can the 6m x 3m be used as a veranda along the back of a house?

Yes — the 6m width makes this pergola exceptionally well-suited for use as a full-length veranda or covered walkway along the rear elevation of a property. It provides continuous covered outdoor space across the full width of many UK homes, creating a seamless transition between indoors and outdoors.

Why choose the 6m x 3m over the 5m x 3m?

If you have the garden space, the extra metre makes a meaningful difference — particularly for those wanting to create three distinct zones beneath the structure (dining, lounge, and bar or kitchen), or for those using it as a veranda where full-width coverage along the house is the goal. The 6m x 3m is also the better choice for larger social gatherings where you need genuine all-weather coverage for a crowd.

Does this pergola need planning permission?

At 6m x 3m, this is a substantial structure and we strongly recommend obtaining confirmation from your local planning authority before installation. Depending on your garden size, property type, and location, permitted development thresholds may apply. Our team is happy to advise, but formal planning confirmation must come from your local council.

What makes the Leviathan different from cheaper pergolas?

The Leviathan is a Dunster House product built from slow-grown spruce, not cheap pine. The denser grain structure makes it significantly stronger and more durable. Combined with 120mm x 120mm posts, full pressure treatment, Smart Seal finishing, and precision pre-notched rafters, the Leviathan is engineered to carry a 6m span with complete structural confidence — something a budget pergola simply cannot do.

What is the difference between pressure treated and dip treated timber?

Pressure treatment forces preservative deep into the timber fibres under pressure, providing long-lasting protection from the inside out. Dip treatment only coats the surface and offers far less protection over time. The Leviathan uses full pressure treatment plus Smart Seal as an additional protective layer — backed by a 10-year guarantee against rot and insect infestation.

Can I grow climbing plants on this pergola?

Absolutely — and the 6m span makes this the most spectacular pergola in the entire range for climbing plants. Wisteria, roses, jasmine, clematis, and ivy can spread across the full six metres of rafter, creating a breathtaking living canopy that completely transforms the feel of your garden or outdoor entertaining space.

Are all fixings included?

Yes — all fixings needed for assembly are included at no extra cost. As professional installation is included as standard, our team handles the entire build for you.

What is the guarantee?

The Leviathan Wooden Pergola 6m x 3m comes with a 10-year guarantee against rot and insect infestation on the pressure treated timber, provided the care instructions supplied by Dunster House are followed.