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Spacious 15x20 ft greenhouse with an elegant large cupola, featuring expansive glass panels and a durable frame, set against a clear blue sky.

Exaco Janssens Cathedral Victorian Greenhouse with Large Cupola 15 x 20 ft

by Exaco

SKU Cathedral-Br

$42,999.00 - $42,999.00

$42,999.00

$45,999.00

$45,999.00 - $45,999.00

$45,999.00

Benefits

Best For

Bonuses

Elevate Your Backyard with top of the line premium glass greenhouse that prevents replacing cheap polycarbonate greenhouses every year.
Massive Accessory Customizations allow you to design the greenhouse to fit the style of your backyard.
Indulge In All That Extra Space with your family, neighbors, children, and most importantly your plants.
Make Your Neighbors Jealous with a finely designed outdoor shade solution.

Serious Plant Parents: Ideal for those who love growing plants all year round or need a separate space for other activities.
All-Season Growing: Perfect for individuals who want to enjoy an enclosed space year-round, regardless of the weather.
Design Enthusiasts: Tailored for homeowners who appreciate the beauty of natural of a premium glass greenhouse in their backyard.

Risk-Free Purchase: We provide replacement parts free of cost.
Premium European Quality: Proudly designed and assembled in Belgium. 15 Year Standard Warranty.
Exaco Preferred Dealer And No Sales Tax (ex NV)
Lowest Prices Or We Price Match (Rules Apply)

Quantity

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Shipping & Handling For Exaco

Handling Time: Ships in 5 to 9 business days. Custom items may take longer.

Shipping Time: Please allow 2-9 business days for delivery to your curbside.

Our goal is to get your order to you as quickly as possible. This item ships to all States of the contiguous U.S.A (lower 48). Please note that all shipments over 100lbs go by LTL freight. For more information check out our Shipping Policy.

Cancellation/Return Policy For Exaco

Return Policy: Exaco generally does not accept returns as everything is built to order. Exceptions apply.

Any order can be canceled within 24 hours of payment.

After 24 hours, most orders will be packed and placed for pickup by the shipping carriers. Once picked up, the item will be considered shipped.

Custom, Built-To-Order, on demand products cannot be canceled or refunded after 24 hours, as these products are put into production specifically for your order.

Damaged Items:

All orders are protected by the manufacturer's warranty. We will repair, or replace any item damaged during shipment or faulty upon arrival as long as the documentation is provided.

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Transform Your Garden with a Majestic Janssens Cathedral Victorian Greenhouse!

The Exaco Cathedral Greenhouse stands out as one of the largest greenhouses, featuring a unique cupola that boosts both height and curb appeal. ike all Janssens greenhouses, it boasts 4mm tempered glass and an aluminum frame, making it tough enough to handle wind gusts and most hail.

The Cathedral’s structure is further strengthened by thick aluminum portal frames spanning its entire width, which increases its stability in sustained winds and snow. Additionally, its doors and windows can be placed almost anywhere, providing excellent design flexibility.

A stunning glass greenhouse with a roof, perched atop a hill. Exaco Janssens Cathedral Victorian Greenhouse with Large Cupola, 15 x 20 ft.

Customize Your Outdoor With A Victorian Greenhouse

Grand Growing Space – Measuring 19'11" x 15' with a soaring 12'2" peak height and 6'8" sidewalls, this Victorian greenhouse delivers 298 sq. ft. of room for plants, projects, and year-round gardening.
Timeless Style, Modern Strength – A 25° roof pitch paired with a choice of Black or Bronze finish creates a striking focal point, while 17-gauge tubular aluminum extrusions and heavy-duty portal frame supports ensure exceptional durability.
Clear & Strong Glazing – 4mm tempered glass panes offer stunning clarity, excellent insulation, and secure protection for your plants in all seasons.
Multiple Entry Options – Features an impressive double hinged door for a welcoming main entry and a sliding door for quick and easy access.
Advanced Ventilation – Includes 4 roof vents with spindle openers, 2 push-out side windows, and 2 louvre windows with automatic openers to keep your greenhouse perfectly balanced.
Built for Year-Round Use – From robust framing to precision glazing, every detail is engineered for beauty, longevity, and optimal plant health.

A 15x20 ft Victorian cathedral greenhouse surrounded by lush garden, with a distinctive large cupola and green framework.

A Place to Grow Plant Babies, Relax In Style, and Enjoy Nature

If you're serious about gardening, you'll love the thoughtful features designed to make your life easier. The standout ventilation system helps you easily control the temperature and airflow inside. This means your plants get the fresh air they need to stay healthy and thrive. No more worrying about overheating or poor air circulation—this greenhouse has got you covered.

But this greenhouse isn’t just for plants. It’s also great as a cover for a hot tub or an outdoor sunroom. Picture yourself relaxing in a hot tub surrounded by your garden or enjoying tea in a cozy sunroom. The beautiful Cathedral Victorian design adds charm and value to your property. It’s more than a greenhouse—it’s a place to unwind and enjoy the outdoors in style.

Elegant and stately 15x20 ft cathedral Victorian greenhouse with a large cupola, perched atop a manicured garden path with colorful flowers.

Specs of the Large Cathedral Victorian Greenhouse

Main Dimensions	15' W x 19'11" L x 12'2" H
Second Level Nook Dimensions	5'4" W x 10'2" L
Floor Space	298 Square Feet
First Gutter Height	6'8" H
First Ridge Height	9'1" H
Second Gutter Height	10'9" H
Second Ridge Height	12'2" H
Cupola Dimensions	10'2" L x 5'4" W with pre-welded frame (horizontal part)
Aluminum Supports	2 Heavy-Duty Aluminum Reinforcement Supports (from front to back) - 2.3" W x 5.2" D
Door	1 Set of Double Hinged Doors, 1 Sliding Door
Windows	4 Roof Vents, 2 Push Out Side Windows, 2 Louvre Window
Window Openers	4 Spindle (Roof), 2 Automatic (Louvre)

Technical sketch of a large cupola Victorian cathedral greenhouse measuring 15x20 ft, with marked dimensions for architectural planning.

Product Installation Instructions for Exaco Cathedral

Exaco Janssens Royal Cathedral Manual

Keep Your Greenhouse Dry and Protect Your Plants with Built-In Gutters and Downspouts

The greenhouse includes gutters and a downspout to efficiently manage rainwater, protecting your plants and keeping the surrounding area dry and tidy. These features collect rainwater from the roof, directing it away to prevent water damage and erosion, ensuring stability even during heavy rain. Note that while some Janssens models include gutters and downspouts as standard, they are not available for separate purchase or retrofitting onto other models.

Top view and close up the gutter with downspout included in some models of Exaco Victorian Greenhouses

Close up of the downspout included in some models of Exaco Victorian Greenhouses

Maximize Space in Your Cathedral Greenhouse with Multi-Functional Shelving

Upgrade your Cathedral Greenhouse with these shelving add-ons. They help maximize space, providing ample room to organize plants, gardening tools, and other items, ensuring your greenhouse is efficient and easy to use.

Top Shelf

Increase your greenhouse workspace with a full-length top shelf, available in dark green or black, measuring 19'10" L x 4" W.

Elevated greenhouse staging with green frame and white tray liner, ideal for seed starting and plant propagation.

Bottom Shelf (Seed Tray)

The seed tray simplifies working with plant materials and keeps your greenhouse tidy. Available in dark green or black, it measures 19'10" L x 20" W x 4" D, with a bottom made of corrugated plastic interlocking inserts.

Black powder-coated slatted shelving installed in a Victorian-style greenhouse, maximizing space for seed trays and potted plants.

Slat Shelving - 2 & 5 Slats

Affordable shelving for all Victorian Greenhouses, available in 2-slat (9" W x 59" L) or 5-slat (21" W x 59" L) configurations, in black or dark green. Shelves can connect end-to-end for extended length.

Keep Your Plants Happy and Healthy with Superior Ventilation Upgrades

Exaco Royal Victorian greenhouse with push-open side window for ventilation.

Push Open Side Windows

Push-open window for greenhouse side walls, hinged at the top. Comes in dark green or black, includes extra glass panel, measuring 40 ½” x 30 ½”.

Side Window Fly Screen

The factory-assembled push-out side window fly screen is easy to install, fitting inside the push-out window with a brush seal opening for the window device.

Close up image of a louvre window with 11 glass panels

Additional Louvre Window

Window with 11 glass panels and an extra piece for below, suitable for Royal or Junior Victorian Greenhouses. Manual operation, black color, with an available auto-opener.

Louvre Window Fly Screen

The pre-assembled fly screen for louvered windows is available in green or black and attaches easily outside with a simple clip, requiring no tools for installation.

Louvre Window Cover

A clear Lexan panel covers the louvered window during the winter season, with a 4mm thickness, measuring 40" x 28", and fits without the need for an attaching mechanism.

Exaco Louvre Window Opener for Cathedral Greenhouse

Louvre Windows Opener

Automatically opens and closes the louvre window based on greenhouse temperature changes using a paraffin oil-filled tube and a heavy spring mechanism.

Exaco Royal Victorian greenhouse roof vents open for ventilation, with sunlight shining through.

Additional Roof Vent

All Janssens greenhouse models include at least 1 roof vent, with the option to add more. They are available in dark green and black, measuring 30 ½” x 32 ½”.

Roof Vent Fly Screen

Factory assembled for easy installation, mounts under the roof vent window with brush seals for auto or spindle opener access, available in green or black.

Manual Roof Window Opener

Designed like a large threaded screw, compatible with Royal or Junior Victorian greenhouses. Please note: a long handle is required for operation (not included).

Automatic Roof Window Opener

For Royal or Junior Victorian Greenhouses, opens windows up to 14 inches at 72ºF using paraffin oil, closing with a spring as temperatures drop—no electricity needed!

Improve Convenience with Custom Door Choices

Janssens Royal Victorian Greenhouse with stylish black frame and glass panels, furnished as an outdoor living space with a fire pit and wicker furniture.

Sliding Door - Single or Double Configuration

Available as a single door or double door in black or green finish to match your greenhouse. Low threshold option is available for both sizes.

Note: Original doors still come with the greenhouse—you must request their removal.

Janssens Greenhouse Double Hinged Door - perfect for wide entryways and easy access in your backyard greenhouse.

Hinged Door - Double Configuration

Double configuration hinged door with low threshold entry, available in black or green to match your greenhouse, and comes with lockable doors.

Close up of drop door kit for hinged and sliding doors for Exaco Royal Victorian Greenhouses

Drop Door Kit - Hinged Doors & Sliding Doors

Allows placement of a Royal Victorian greenhouse on a 20" to 36" high perimeter wall (24" recommended), without new glass panels (source locally). Additional polycarbonate available for cutting. Use "Lowered Threshold" with dropped doors; provide exact wall height for accurate cutting.

Exaco Royal Victorian Lowered Threshold Sliding Door Installation Guide

Lower Threshold Kit

The 2025 Lower Threshold Kit for Janssens Royal Victorian greenhouses lowers the entry height to just 1¼", making access more convenient. Its bottom-only design can be trimmed to fit single doors or buy another kit for double sliding doors.

Photo of the Door Stopper installed in the bottom of the door.

Hinged Door Stopper

Durable black door stop with built-in latch holds doors securely open. Standard with original hinged doors unless alternate hardware is chosen.

Photo of the Auto closer installed at a green door.

Hinged Door Auto Closer

Commercial-style auto closer with adjustable arm gently pulls doors shut. Fits greenhouses on knee walls; allows up to 120° opening for safety and convenience.

Magnetic Hinged Door Holder

Perfect for greenhouses on stem walls, this sturdy magnetic holder keeps hinged doors open at 90°. Easy to use, reliable, and highly effective in windy conditions.

Master Climate Management with Add-Ons for Exaco Greenhouses

Exaco Victorian Greenhouse Exhaust Vent with Fan for optimal temperature control and ventilation.

Exhaust Fan

The exhaust fan keeps fresh air moving in your greenhouse for a healthier growing environment. For easy setup, pair with the Lexan panel. Add a thermostat to automate it—otherwise, it runs continuously.

Exaco Solar Exhaust Fan System

Provides ventilation featuring a 50-watt solar panel, 16" CE approved fan, thermostat, and a 20-foot-cord. Batteries not included. Must order with lexan panel for easy installation.

Automated aluminum louver Exaco Modern greenhouse vent for temperature and humidity control.

Intake Shutter Vent

Designed to use with an exhaust fan, allows controlled airflow through the greenhouse. It helps maintain the ideal environment for the plants by regulating ventilation.

Close-up of Exaco INKBIRD ITC-608T thermostat with dual probes.

Inkbird Thermostat

Inkbird ITC-608T thermostat with dual probes controls 2 heating/cooling devices separately. Plug-and-play, 120V/15A/1800W, range -40°F–212°F.

Industrial Heater

Keep big greenhouses warm with this industrial infrared heater. Delivers 18,500 BTU, with fan and thermostat controls for steady heat.

Create the Perfect Greenhouse Retreat with These Key Extras

A solar-powered LED light mounted on a white wall.

Solar Powered Light

Eco-friendly solar LED light for greenhouses/sheds. 250 lumens, 4 hrs runtime, cool white 6000K. Easy install, weather-resistant, 2-yr warranty. Not a grow light.

Astrica Grow Light

Boost growth with the ASTRICA 45W Interlight LED. F3 spectrum, 112 μmol/s, 2.5 μmol/J. IP65 durable, link up to 12 units. Note: Please let us know if you are stringing units together - it needs different cables.

Scroll Supports

Add strength and charm to your 20+ ft greenhouse with this 3-piece dark green scroll support set. Includes two shoulder and one roof support. Note: curtains won’t slide past the scrolls.

Roof Bracing

Roof Bracing with adjustable turnbuckle, made of 2 flat bars (~41" x 0.75" x 2mm). Adds strength to greenhouses. Available in aluminum, green, or black finishes.

Wheelbarrow Ramp

The strong rubber ramp, 49cm wide, 31cm long, and 10cm high, allows easy access for a wheelbarrow into the greenhouse.

Stainless Steel Plant Hooks for Exaco Greenhouses

Adjustable Metal Hooks

Stainless steel T-bolts install easily in greenhouse channels. Adjustable, rust-resistant, ideal for hanging plants, lights, or tools. Available in J Hooks and Pipe Hooks.

T Bolts

Stainless steel hammerhead bolts and nuts for attaching accessories in aluminum frame channels. Specifications include 20 bolts and nuts per set, with 6mm bolt heads, available in 12mm or 15mm lengths.