The Janssens Cathedral Victorian Glass Greenhouse is a versatile, spacious, feature packed addition to any garden or backyard. The large floor size, tall sides, and extended roof cupola section allow space for all of your plant growing needs, or use it as a hot tub cover or outdoor sunroom.
This model is a customized configuration for the Cathedral in Black, in two sizes: 15x25 ft, and 15x30 ft, both with 80 in. high side walls, and a 12 ft ridge height at the roof peak.
The attractive looks of the Cathedral Greenhouse are matched by superior strength from pre-welded aluminum framing and 4mm tempered glass construction. This choice of glass provides a high degree of safety.
These customized Janssens Cathedral Glass Greenhouses are configured as follows:
- Special narrow glass panels for a beautiful vintage look. The narrow glass also adds a lot of flexibility for window placement.
- Four large heavy-duty portal frames for strength.
- Six roof vents with heavy duty heat-operated automatic openers (no electricity required) and fly screens on the 25 ft model. Eight roof vents with openers and fly screens on the 30 ft model.
- Two louver windows on the 25 ft model with automatic openers (no electricity required) to help keep the interior at a comfortable temperature, equipped with fly screens. Four louver windows on the 30 ft model.
- Four large side windows with fly screens on the sides that tilt open for added ventilation,
- A wide set of lockable double sliding doors for easy access, Lower threshold kit included, for easy entry and exit.
- A set of lockable double hinged doors.
- One 2-slat 9" deep shelf unit, 59" long and spans 4 of the narrow glass wall panels.
- One 5-slat 21" deep shelf unit, 59" long and spans 4 of the narrow glass wall panels.
This is a premium, large size structure that can be used for multiple purposes and will add value to your home.
Please call us at 888-648-5333 to schedule a free design session. You can customize the size, frame color, benches and shelves, extra doors, windows, and roof vents, shelving, and many other functional and decorative aspects of your greenhouse.
Take advantage of this beautiful greenhouse to create a unique area to enjoy.
- House a Jacuzzi Tub and surround it with your favorite plants
- An Inspiring Art/Hobby Studio
- A Tea House
- A Planetarium
- An Entertainment Room
- A Yoga/Exercise Room
- A Mediation/Relaxation/Reading Sanctuary
- A retreat to enjoy fresh air and sunlight
- A standalone retail space
- House a swimming pool
This greenhouse is not designed to be a build-it-yourself-kit. It should be mounted by experienced builders who are familiar with these products and their assembly. Due to the size of this greenhouse we recommend that you check your local building code for any required permits and view the foundation construction guide prior to ordering.
NOTE: These custom configured Cathedral Greenhouses are available by special order only. Please call (888) 648-5333 for ordering information, including cash payment discount when paying with a bank wire transfer. Standard delivery service is curbside with lift gate. We have an added-cost flatbed plus forklift delivery option available if needed.
FEATURES
- 2 Available Sizes: 15x25, 15x30
- 1 set of lockable hinged double doors with closers, low threshold
- 1 set of lockable sliding double doors, low threshold
- 4 top hanging side windows with screens
- 15x25 unit
- 2 louver windows with automatic openers (no electricity needed) and fly screens
- 6 roof windows with automatic openers (no electricity needed) and fly screens
- 15x25 unit
- 4 louver windows with automatic openers (no electricity needed) and fly screens
- 8 roof windows with automatic openers (no electricity needed) and fly screens
- 4mm tempered glass
- 4 Heavy Duty 2x5 inch aluminum reinforcement Portal Frame Supports.
- Cupola with pre-welded frame
SPECIFICATIONS
- 2 Available sizes:
- 15ft x 24ft 8 in = 370 sf
- 15ft x 29ft 6in = 442.5 sf
- First gutter height: 6' 8"
- First ridge height: 9' 1"
- Second gutter height: 10' 9"
- Second ridge (roof peak) height: 12' 2"
- Glazing: 4mm tempered glass
- T.U.V. & GS tested and approved, which is similar to UL testing & listing
INSTALLATION MANUAL

About Janssens Greenhouses
Janssens Greenhouse Assembly Overview
What Makes Janssens a Quality Greenhouse Brand
Janssens greenhouses are renowned for their European craftsmanship, superior materials, and long-lasting design. Every detail is built to exceed the standards of most competitors in the same price range, ensuring exceptional performance and visual appeal.
Premium Construction and Materials
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Heavy-duty aluminum frame: Janssens uses thicker, stronger aluminum profiles than most greenhouse brands, giving each structure superior rigidity and weather resistance.
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Corrosion-proof hardware: All fittings are made from stainless steel, preventing rust or deterioration in humid or outdoor environments.
High-Performance Glazing
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4 mm tempered safety glass: While many greenhouses use 3 mm glass, Janssens provides thicker, TÜV and GS-certified tempered glass for better insulation and durability against wind, hail, and impact.
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Full-length glass panels: Each glazing sheet is a single, unbroken panel that creates a sleek, modern appearance—unlike the overlapping or segmented panels found on many other brands.
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Weather-tight sealing system: Heavy-duty rubber gaskets hold the glass securely in place, improving insulation and reducing heat loss during colder months.
Smart Design Advantages
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Integrated foundation frame (4” high): Included with every Janssens greenhouse, providing a stable, level base that other brands often charge extra for.
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European engineering standards: Janssens greenhouses are precision-built and independently tested for strength, safety, and long-term reliability.
Optional Accessories
Doors
- Additional Sliding Doors
- Additional Hinged Doors
- Lowered Threshholds for Doors
- Drop Kits for Doors (to place on a knee wall)
Windows
- Additional Roof Vents
- 'Push-Open' Side Windows
- Additional Louvre Windows
- Fly Screens for Roof vents
- Fly Screens for Push Open Side Windows
- Fly Screens for Louvre Windows
- Manual Openers for Roof or Side Windows
- Automatic Openers for Roof or Side Windows
- Automatic Openers for Louvre Windows
- Covers for Louvre Windows
- Restraint Cable System for Roof Vents
Shelving
- Top Shelf
- Bottom Shelf (Seed Tray)
- Slatted Shelving
Climate Moderation
- Wooden Roof Shades
- Shade Curtain
- Roll-Up Shades
- Exhaust Fan
- Solar Powered Exhaust Fan
- Intake Vent
- Palma Heater
- Big Red heater
- Digital Thermostat
Miscellaneous
- Wheelbarrow Ramp
- Metal Plant Hooks
- Solar Powered Light
- Grow Light
- Scroll Supports
- T Bolts

PRODUCT DESCRIPTION

