{"product_id":"leviathan-diamond-corner-pergola-3m-x-3m-120mm-posts-smart-seal-treated-nationwide-installation-included-dunster-house","title":"Leviathan Diamond Corner Pergola 3m x 3m | 120mm Posts | Smart Seal Treated | Nationwide Installation Included | Dunster House","description":"\u003ch2\u003eLeviathan Diamond Corner Pergola – 3m x 3m | 120mm Posts | Smart Seal Timber Treatment\u003c\/h2\u003e\n\u003cp\u003eMake a bold statement in your garden with the \u003cstrong\u003eLeviathan Diamond Corner Pergola\u003c\/strong\u003e by \u003cstrong\u003eDunster House\u003c\/strong\u003e — the premium, heavy-duty corner pergola built for those who refuse to compromise on quality. With \u003cstrong\u003emassive 120mm x 120mm upright posts\u003c\/strong\u003e, a striking \u003cstrong\u003ediamond roof design\u003c\/strong\u003e, and a footprint of 3m x 3m, the Leviathan commands attention and delivers an outdoor living space that feels truly architectural.\u003c\/p\u003e\n\u003cp\u003eCrafted from \u003cstrong\u003eslow-grown, pressure treated spruce\u003c\/strong\u003e and finished with \u003cstrong\u003eSmart Seal timber sealant\u003c\/strong\u003e, this pergola is engineered to withstand the British climate for a decade and beyond — backed by a \u003cstrong\u003e10-year guarantee against rot and insect infestation\u003c\/strong\u003e. Smart Seal provides a superior protective barrier that locks out moisture and UV damage, keeping the timber looking and performing at its best for years to come.\u003c\/p\u003e\n\u003cp\u003e🌟 \u003cstrong\u003eThe price includes professional nationwide installation and Smart Seal timber treatment — both included free of charge.\u003c\/strong\u003e Our experienced fitting teams install across the whole of Mainland UK, handling everything from delivery to final fitting so you can enjoy your Leviathan from day one.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eImposing 120mm x 120mm upright posts\u003c\/strong\u003e — exceptional structural strength and premium visual impact\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eDistinctive diamond roof design\u003c\/strong\u003e — architectural elegance that elevates any garden\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eFully pressure treated slow-grown spruce\u003c\/strong\u003e — long-term rot and insect resistance\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eSmart Seal timber treatment included free of charge\u003c\/strong\u003e — superior moisture and UV protection\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003e10-year guarantee\u003c\/strong\u003e against rot and insect infestation\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eNationwide installation included as standard\u003c\/strong\u003e — anywhere across Mainland UK, free of charge\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eCorner-fitting design\u003c\/strong\u003e — maximises use of garden corners and boundary spaces\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003e7.42m² internal area\u003c\/strong\u003e — generous usable space for dining, entertaining, or relaxing\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003ePre-cut, pre-notched, planed timber\u003c\/strong\u003e — precision engineered for a clean, professional finish\u003c\/li\u003e\n  \u003cli\u003e✅ \u003cstrong\u003eAll fixings supplied\u003c\/strong\u003e — everything needed is included\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOverall External Dimensions:\u003c\/strong\u003e 3.321m x 3.321m (10' 10.75\" x 10' 10.75\")\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eExternal Width:\u003c\/strong\u003e 3.040m (9' 11.75\")\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eExternal Depth:\u003c\/strong\u003e 3.040m (9' 11.75\")\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eInternal Width:\u003c\/strong\u003e 2.724m (8' 11.25\")\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eInternal Depth:\u003c\/strong\u003e 2.724m (8' 11.25\")\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eInternal Area:\u003c\/strong\u003e 7.42m²\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOverall Height:\u003c\/strong\u003e 2.350m (7' 8.25\")\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eInternal Eaves Height:\u003c\/strong\u003e 2.260m (7' 5\")\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUpright Posts:\u003c\/strong\u003e 120mm x 120mm\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTimber:\u003c\/strong\u003e Slow Grown Spruce (Fully Pressure Treated)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTimber Finish:\u003c\/strong\u003e Smart Seal (included)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGuarantee:\u003c\/strong\u003e 10 Years against Rot and Insect Infestation\u003c\/li\u003e\n  \u003cli\u003e\u003cem\u003eAll sizes quoted are nominal. All fixings supplied. Timber is pre-cut, pre-notched, and planed.\u003c\/em\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhy Choose Bespoke Oak and Slate?\u003c\/h3\u003e\n\u003cp\u003eAt Bespoke Oak and Slate, we supply and install premium Dunster House garden structures across the UK. Every Leviathan order includes \u003cstrong\u003eprofessional installation and Smart Seal timber treatment as standard — completely free of charge\u003c\/strong\u003e. No hidden costs, no surprises — just a beautifully installed, fully treated pergola ready for you to enjoy.\u003c\/p\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\n\u003ch4\u003eDoes the price include installation?\u003c\/h4\u003e\n\u003cp\u003eYes — \u003cstrong\u003eprofessional nationwide installation is included in the price, free of charge\u003c\/strong\u003e. Our experienced fitting teams cover the whole of Mainland UK. The price you see is the price you pay — fully installed, no extras.\u003c\/p\u003e\n\n\u003ch4\u003eWhat is Smart Seal and is it included?\u003c\/h4\u003e\n\u003cp\u003e\u003cstrong\u003eSmart Seal is a premium timber sealant\u003c\/strong\u003e that provides a superior protective barrier against moisture penetration, UV damage, and weathering. It goes beyond standard pressure treatment to keep your pergola looking and performing at its best for longer. \u003cstrong\u003eSmart Seal application is included free of charge\u003c\/strong\u003e with every Leviathan order — applied by our installation team as part of the fitting process.\u003c\/p\u003e\n\n\u003ch4\u003eDo you install anywhere in the UK?\u003c\/h4\u003e\n\u003cp\u003eYes. We install \u003cstrong\u003eanywhere across Mainland UK\u003c\/strong\u003e at no extra cost. From Cornwall to Caithness, our professional teams will come to you regardless of your location.\u003c\/p\u003e\n\n\u003ch4\u003eWhy does the Leviathan have 120mm posts?\u003c\/h4\u003e\n\u003cp\u003eThe \u003cstrong\u003e120mm x 120mm upright posts\u003c\/strong\u003e are significantly larger than those found on standard pergolas, providing exceptional structural rigidity, a premium heavyweight appearance, and the ability to support additional wall panels, roofing options, and climbing plants without any flex or movement. This is what sets the Leviathan apart as a truly premium structure.\u003c\/p\u003e\n\n\u003ch4\u003eIs the Leviathan Diamond Corner Pergola pressure treated?\u003c\/h4\u003e\n\u003cp\u003eYes. All timber is \u003cstrong\u003efully pressure treated slow-grown spruce\u003c\/strong\u003e, providing long-term resistance to rot and insect infestation. It is also finished with \u003cstrong\u003eSmart Seal\u003c\/strong\u003e for additional moisture and UV protection. The pergola comes with a \u003cstrong\u003e10-year guarantee\u003c\/strong\u003e against rot and insect damage.\u003c\/p\u003e\n\n\u003ch4\u003eWhat is the internal usable space?\u003c\/h4\u003e\n\u003cp\u003eThe Leviathan offers a generous \u003cstrong\u003e7.42m² internal area\u003c\/strong\u003e, with an internal width and depth of 2.724m (8' 11.25\") each — plenty of room for outdoor dining furniture, a sofa set, or a hot tub enclosure.\u003c\/p\u003e\n\n\u003ch4\u003eWhat are the overall dimensions of the Leviathan?\u003c\/h4\u003e\n\u003cp\u003eThe overall external footprint is \u003cstrong\u003e3.321m x 3.321m\u003c\/strong\u003e (10' 10.75\" x 10' 10.75\"), with an overall height of 2.350m (7' 8.25\") and an internal eaves height of 2.260m (7' 5\"). All sizes are nominal.\u003c\/p\u003e\n\n\u003ch4\u003eCan I add wall panels, decking, or a roof to the Leviathan?\u003c\/h4\u003e\n\u003cp\u003eYes — the Leviathan is designed to be highly customisable. Optional extras include \u003cstrong\u003efull-height panels, glazed panels, half-height panels, decking, protective paint, and roof trellis\u003c\/strong\u003e for growing plants and additional shelter. Please contact us to discuss the options available for your project.\u003c\/p\u003e\n\n\u003ch4\u003eDoes this pergola need planning permission?\u003c\/h4\u003e\n\u003cp\u003eIn most cases, a pergola of this size falls within \u003cstrong\u003epermitted development rights\u003c\/strong\u003e and does not require planning permission, provided it meets standard conditions (e.g. not covering more than 50% of garden area, not positioned forward of the principal elevation). We always recommend checking with your local planning authority if you are unsure.\u003c\/p\u003e\n\n\u003ch4\u003eIs the timber pre-cut and ready to install?\u003c\/h4\u003e\n\u003cp\u003eYes — all timber is \u003cstrong\u003epre-cut, pre-notched, and planed\u003c\/strong\u003e for a precise, professional finish. All fixings needed for assembly are supplied. As installation is included as standard, our team handles the entire build for you.\u003c\/p\u003e\n\n\u003ch4\u003eHow long does installation take?\u003c\/h4\u003e\n\u003cp\u003eInstallation is typically completed in a single visit by our professional team. Lead times vary by location and current demand — please \u003cstrong\u003econtact us directly\u003c\/strong\u003e for an accurate timeline for your area.\u003c\/p\u003e\n\n\u003ch4\u003eWhat is the guarantee on the Leviathan?\u003c\/h4\u003e\n\u003cp\u003eThe Leviathan comes with a \u003cstrong\u003e10-year guarantee against rot and insect infestation\u003c\/strong\u003e on the pressure treated timber, provided the care instructions supplied by Dunster House are followed.\u003c\/p\u003e\n\n\u003ch4\u003eHow does the Leviathan compare to the Utopia Diamond Corner Pergola?\u003c\/h4\u003e\n\u003cp\u003eThe Leviathan is the \u003cstrong\u003epremium, heavy-duty version\u003c\/strong\u003e of the diamond corner pergola range. Its key differentiators are the \u003cstrong\u003e120mm x 120mm posts\u003c\/strong\u003e (vs 70mm on the Utopia), greater internal height, larger internal area, and the inclusion of \u003cstrong\u003eSmart Seal timber treatment\u003c\/strong\u003e. It is the choice for those who want the most substantial, impressive structure available.\u003c\/p\u003e","brand":"Dunster House","offers":[{"title":"Default Title","offer_id":61599033524554,"sku":null,"price":2850.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1026\/5572\/1802\/files\/Leviathan-corner-Day-1.webp?v=1776098463","url":"https:\/\/www.bespokeoakandslate.com\/products\/leviathan-diamond-corner-pergola-3m-x-3m-120mm-posts-smart-seal-treated-nationwide-installation-included-dunster-house","provider":"Bespoke Oak and Slate","version":"1.0","type":"link"}