Grandio Summit 12x20 #SKU SUMMIT-1220

Welcome to the Grandio Summit 12×20

This beautiful barn-style greenhouse gives you a year-round growing space with a heavy-duty aluminum frame and 10mm twin-wall polycarbonate panels.

Engineered to perform in harsh environments, the Grandio Summit’s rugged durability makes it one of the most insulated greenhouses on the market. Its barn shape design is both elegant and functional, allowing plenty of growing space while looking great in your yard.

Made to meet the highest standards of hobby and professional gardeners alike, the 1.6mm profile aluminum frame provides a stronger and more durable build than its competitors.

The Summit’s range of features and accessories provides a well ventilated growing space with ample roof windows and re-engineered sliding double doors. The UV-protected 10mm paneling has an (R) value of 1.89* and heat loss (U) value of 0.53, allowing for optimal insulation in all climates.

The doors are hung from above which eliminates jamming and the door wheels are made from high-quality nylon for durability. The door wheel bolt is turned from solid brass with a smooth shank to reduce wear. The doors come standard with heavy-duty lockable door handles and included key.

Carefully engineered to the highest standards, gardeners of all types will love the combination of strength, quality, performance, and value that Grandio Greenhouses are known for.

Reach the Summit with Grandio!

Cover Your Bases

Concrete Slab or Wood Deck Installation: If you plan on constructing your Summit on a concrete slab or wooden surface, the included Flat Mount Base Kit will offer solid footing. The Flat Mount Base Kit includes your choice of anchors for concrete slab or wooden surfaces.

In-earth Installation: If you plan to install your Grandio Summit Greenhouse directly into the earth, we highly recommend our Steel Base Kit with Earth L-Bolt Anchor Kit. The Steel Base Kit is powder coated to resist rust and decay and is designed to be buried into the ground or back filled with gravel providing a solid foundation to combat wind and other extreme environments. Just select “Base Kit (Earth L-Bolt Anchor Kit)” when you checkout and you’ll get everything you need

Take A Closer Look

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Incredible Warranty

Our lifetime frame warranty and 10-year panel warranty do more than give you peace of mind, it’s a commitment from us to maintain a high degree of quality, dependability and reliability. Our Grandio Greenhouses are custom made to meet high standards and quality manufacturing to withstand extreme wind and weather conditions.

*R-Value – the measurement of ‘insulating ability’ of the material. Higher R-Value refers to higher insulation value.

*U-Value – the measurement of ‘heat loss’ through the material. The lower the U-Value the less heat is escaping.

Technical details for those who need more.

• Height: 9.5′
• Width: 12′
• Length: 20′
• Frame: Heavy duty aluminum.
• Wind Rating: Withstands winds up to 76 mph*
• Snow Rating: Maximum snow load of 25lbs./ft² of snow*
• Color: Powder coated green.
• Panels: 10mm twin-wall UV protected polycarbonate.
• Door Size: 41.5″ W x 85″ H
• Doors: Bind-resistant sliding double-doors.
• Latch: Magnetic latch doors with key lock.
• Reinforcement: Cross-roof truss and cross corner bracing.
• Tools: Included
• Hardware: Stainless steel nuts and bolts.
• Gutters: Built-in rain gutters.
• Ventilation: (10) roof vent with adjustable manual openers/latches

Looking for assembly instructions? Find them here.

This is your resource for finding complete assembly instructions for all Grandio Summit Greenhouses. You can download the instructions in PDF format or you can view the assembly video. We’ve provided everything you need to get started with your new Grandio greenhouse. 

Grandio Summit Greenhouse Assembly Manuals

» Download: Grandio Summit Manual 1 – Base Kit Assembly Instructions and Installation
» Download: Grandio Summit Manual 2 – Summit Greenhouse Assembly Instructions
» Download: Grandio Summit Manual 3 – Itemized Parts List, Graphics, Descriptions and Quantities

Grandio Summit Greenhouse Anchoring Kit Manuals

» Download: Grandio Summit Manual 1 – Flat and Earth Base Kit Assembly with Earth Anchoring Kit
» Download: Grandio Summit Wood Anchoring Kit Supplement Manual
» Download: Grandio Summit Concrete Anchoring Kit Supplement Manual

Note: In order to read the manuals, you need the Adobe Acrobat PDF reader.

ou have questions, no problem, we have answers.

How easy is the Grandio to assemble? Very easy. We’ve designed and perfected the assembly process with you in mind. We provide the tools and a step-by-step assembly manual and video.

Is a building permit required? You may not need a permit for your Grandio, but it is always a good idea check before you get started. We recommend you check local ordinances and requirements before setting up your greenhouse.

Is it strong enough for windy or heavy snow locations? Definitely. Grandio’s are all designed to withstand the most hostile environments with a wind rating of 76 MPH and snow load rating of 25lbs./ft² of snow. We offer additional roof and eave supports to increase the strength and durability of the greenhouse frame for the Element Greenhouses. Just follow the included directions for securing your greenhouse and you’ll enjoy many years of growing with your Grandio.

I live in the hot southwest will Grandio Greenhouses work for me? For people who live in high temperature areas of the country like Arizona, Texas, California, Nevada, or New Mexico we recommend our aluminum shade net. The aluminum shade net reflects the sun on the hottest days to help your greenhouse keep it’s cool.

How do the automatic roof vent openers work? The opener has a metal cylinder containing a mineral which expands when heated. This pushes a piston that opens the vent. As the temperature cools, the mineral shrinks and a spring closes the vent and resets the piston. The opening and closing of the vent is gradual allowing just the right amount of air flow for cooling. No electricity needed!

How large is the roof vent opening? The vent opening is 18-3/4″ width by 22-3/4” length.

What is the difference in polycarbonate thicknesses? Polycarbonate is available in several different thicknesses and normally comes in single, double, and triple walled sheets that can vary in thickness from 1mm to 10mm. A good rule to remember is that the thicker the panel the better insulation you’ll have for your greenhouse.

Can these greenhouse be mounted to a concrete pad? The Grandio comes standard with a base that is meant to anchor it in the soil with concrete footers or a duckbill anchor kit. However, it can be mounted to a concrete pad with additional tools and hardware. For more information please refer to our online manual.