Janssens | Cathedral Victorian Glass Greenhouse Kit With 4mm Tempered Glass Glazing



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The Janssens Cathedral Victorian Glass Greenhouse is a versatile, spacious, feature packed addition to any garden or backyard. The large floor size (15x15, 15x17, 15x20, 15x22, 15x25, 15x27, or 15x30), 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.

Price shown is for the baseline configuration mentioned below (see Features section), and this baseline configuration can sometimes have a shorter lead time.

Please call us at 888-648-5333 to schedule a free greenhouse design session. You can specify size, frame color, number and type of windows, number and opener types for roof vents, door types and count, bench options, decorative spandrels, finials, roof crest, and more.

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 and impressive insulation value.

The Janssens Cathedral Glass Greenhouse baseline configuration includes:

  • Four roof vents with automatic openers,
  • A louver window to help keep the interior at a comfortable temperature,
  • Two large hanging windows on the sides can also swing up for added ventilation,
  • A wide set of lockable swinging doors for easy access,
  • A single lockable sliding door makes entry simple.

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, the frame color, benches and shelves, 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

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: The Cathedral Greenhouse is available by special order only. Please call (888) 648-5333 for ordering information. It is also recommended that you view the foundation construction instructions and assembly instructions prior to placing your order.  Standard delivery service is curbside with lift gate.  We have an added-cost flatbed plus forklift delivery option available for most locations.

  • 7 Available sizes: 15x15, 15x17, 15x20, 15x22, 15x25, 15x27, 15x30
  • 1 double set of hinged doors with closers, low threshold
  • 1 sliding door, including low threshold kit
  • 2 top hanging side windows
  • 1 louvre window
  • 4 roof windows with automatic openers
  • 4mm tempered glass
  • Heavy duty 2x5 inch aluminum reinforcement portal frame supports from front to back.  2 portal frames on smaller sizes, 3 portal frames on longer units.  You may also order additional portal frames if desired for a stouter structure.
  • Cupola with pre-welded frame (horizontal roof nook part)
  • 7 Available sizes:
    • 15ft x 15ft = 225 sf
    • 15ft x 17ft 5in = 261 sf
    • 15ft x 19ft 10in = 298 sf
    • 15ft x 22ft 3in = 334 sf
    • 15ft x 24ft 8 in = 370 sf
    • 15ft x 27ft = 405 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

15 Year Limited Warranty

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Questions & Answers

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  • How insulated is the greenhouse? Could you still grow plants in 30 degree weather?

    The glass has an R value of 1.2, so you would need significant heating in the greenhouse, depending on the temperatures you needed to maintain inside.

    This site has a lot of handy calculators that can help determine how much heating you would need: https://www.acfgreenhouses.com/greenhouse-heater-size-calculator.aspx

    For higher insulation, I'd recommend either a double-wall or triple-wall polycarbonate greenhouse such as our Hoklartherm RIGA line, or a dual-pane glass greenhouse such as our Holartherm Livingten.

  • Do you have green house size 20’x50’

    Yes, we are able to custom configure some of the Janssens greenhouses up to 20' x 60'. 
    Please call us as 888-648-5333 to discuss your project.

    For the Cathedral model, the largest we can configure is 15' x 30'.

  • Do you have the capacity to manufacture a 2000 sq ft observatory?

    An astronomical observatory?  Only to the extent that a greenhouse (or geodesic dome) could be used for that purpose.  Janssens in particular has the ability to highly customize their buildings, however it would likely be something to explore interactively a bit to see if there are particular requirements that can be accomodated.