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8x12 Janssens Modern Pent Roof Greenhouse

Elevate your gardening experience with the 8x12 Janssens Modern Pent Roof Greenhouse, offering superior strength, ample space, and stylish design. Enjoy peace of mind with a 13-year warranty and customisable options to suit your needs.

More Sizes:

Select your Colour:

Add Door Options?

Hinged Double Door
+ £1,100
Qty 1
Single Hinged Door
+ £495
Qty 1
Double Sliding Door
+ £475
Qty 1
Single Sliding Door
+ £190
Qty 1

Door Options information

Hinged Double Door - £1100.00
Hinged Double Door

Add a set of hinged double doors to your greenhouse


Single Hinged Door - £495.00
Single Hinged Door

Add a Single Hinged Door to your greenhouse


Double Sliding Door - £475.00
Double Sliding Door

Add a set of Double Sliding Doors to your Greenhouse


Single Sliding Door - £190.00
Single Sliding Door

Add a Single Sliding Door to your greenhouse


Add Staging?

Qty 1
Janssens Colour Matched Seed Tray Shelving
+ £295
Qty 1
£15 off
1 Tier Staging Colour Matched
+ £74
Qty 1
Janssens Integrated Colour Matched Shelving
+ £55
Qty 1
£23 off
2 Tier Staging Colour Matched
+ £96
Qty 1
£10 off
Top Tier Staging Extension Colour Matched
+ £49
Qty 1
Qty 1

Staging information

Janssens Colour Matched Full Length Integrated Shelving - £145.00
Janssens Colour Matched Full Length Integrated Shelving

Add the Colour Matched Full Length 458cm long integrated shelving to the side of your greenhouse to help retain your floor space


Janssens Colour Matched Seed Tray Shelving - £295.00
Janssens Colour Matched Seed Tray Shelving

Add the Colour Matched Full Width 310cm long Seed Tray Shelving to the rear of your greenhouse to help retain your floor space


1 Tier Staging Colour Matched - £74.00
1 Tier Staging Colour Matched

This 1 Tier Vitavia Colour Matched greenhouse staging gives you a handy work surface and storage area. Dimensions: 76cm (H) x 50cm (D) x 120cm (W)


Janssens Integrated Colour Matched Shelving - £55.00
Janssens Integrated Colour Matched Shelving

Add the Colour Matched 150cm long x 23cm wide integrated shelving to your greenhouse to help retain your floor space


2 Tier Staging Colour Matched - £96.00
2 Tier Staging Colour Matched

This 2 Tier Vitavia Colour Matched greenhouse staging gives you a handy work surface with additional low level storage. Dimensions: 76cm (H) x 50cm (D) x 120cm (W)


Top Tier Staging Extension Colour Matched - £49.00
Top Tier Staging Extension Colour Matched

This little top level Colour Matched shelf attaches to 1 or 2 Tier staging to give you a bit more storage space


Janssens Colour Matched Integrated Staging - £95.00
Janssens Colour Matched Integrated Staging

Add the Silver 150cm long x 53cm wide integrated staging to your greenhouse to help retain your floor space


Add Ventilation and Shading?

Auto Roof Vent Opener
+ £60
Qty 1
Curtain Shading
+ £27
Qty 1
Qty 1
Auto Louvre Opener
+ £60
Qty 1
Janssens Sunscreen Shading
+ £129
Janssens Roof Vent
+ £95
Qty 1
Janssens Side Vent
+ £320
Qty 1

Ventilation and Shading information

Auto Roof Vent Opener - £60.00
Auto Roof Vent Opener

This automatic opener for your roof vents will automatically open your roof vents to ventilate your greenhouse when it becomes too hot.


Curtain Shading - £27.00
Curtain Shading

Curtain shading will protect your plants from sun scorch and provide shade to moderate temperature. 6ft x 8ft.


Louvre Vent - £130.00
Louvre Vent

A louvre window brings fresh cool air into your greenhouse to moderate the temperature inside. An essential add on.


Auto Louvre Opener - £60.00
Auto Louvre Opener

This automatic opener mechanism will open your louvre window for you when you’re not around. No need to worry about ventilation, this does it automatically for you! (Does not include louvre window).


Janssens Sunscreen Shading - £129.00
Janssens Sunscreen Shading

Add the Janssens retractable shading kit for ease of use


Janssens Roof Vent - £95.00
Janssens Roof Vent

Add roof ventilation to your greenhouse to help moderate the temperature


Janssens Side Vent - £320.00
Janssens Side Vent

Help recirculate the air in your greenhouse with a side vent or two!


Add Extras?

Hygrometer
+ £17
Soil Thermometer
+ £29
Max/Min Thermometer
+ £23
100L Mini Rainsaver Water Butt
+ £54
Qty 1

Extras information

Hygrometer - £17.00
Hygrometer

This Hygrometer will measure the humidity levels inside your greenhouse.


Soil Thermometer - £29.00
Soil Thermometer

This Soil Thermometer will let you track the temperature of your soil inside the greenhouse.


Max/Min Thermometer - £23.00
Max/Min Thermometer

This thermometer will tell you your maximum daytime temperature as well as record the lowest night time temperature in your greenhouse.


100L Mini Rainsaver Water Butt - £54.00
100L Mini Rainsaver Water Butt

Add this 100L water butt kit that includes: Butt, Tap & Lid - Black Stand


The 8x12 Janssens Modern Pent Roof Greenhouse is the perfect building if you are looking for a lot more head height and practical growing space. The unique design makes the Modern a great place to relax with friends while making a striking statement in your garden. Not quite big enough, add a 2ft extension in the options below.

Pick from a green or black powder-coated finish to suit your garden or personal style preferences. Both Hinged and Sliding Double and Single Doors are available as options below to fully customise your greenhouse.

All Janssens Modern Greenhouses are built around a strong box-section aluminium frame and base, with 4mm Toughened Glass held in with proper rubber glazing gasket to take on the worse of UK weather!

Can't find the size or specification to suit your needs?

Most Janssens Greenhouses are fully customisable.

Call us on 0800 098 8877 for your Free Quote!
  • 2360mm x 3830mm Dimensions (7ft 9” x 12ft 5”)
  • 2.7m High Ridge Height
  • Aluminium Frame with Tubular and Box Section for Superior Strength.
  • Green or Black Powder Coated Frame.
  • Box Section Base Plinth.
  • Double Sliding Locking Doors
  • 4mm Full Length Toughened Safety Glass
  • 2 x Automatic Roof Vents
  • 2 x Hinged Side Vents
  • Rubber Glazing Gasket Strips (no fiddly clips)
  • Gutters and 40mm Aluminium Downpipes.
  • Stainless Steel Fittings.
  • Step by Step Instruction Manuals with Instructional DVD.
  • 13 Year Manufacturers Warranty.
  • Fully Customisable Door and Windows are available as Options below.
  • Many Accessories Available - Scroll down this page.

Delivery is currently within 8 weeks for Urban Models, 10-12 Weeks for Master Models and 16 weeks for all other models to UK Mainland. Your exact delivery day will be confirmed with you at least 3 days before the day by telephone.

Please note Some Scottish postal codes are subject to delivery charges.

Optional Installation information: Installation will be carried out around 14-21 working days after delivery. Optional Installation will only be carried out on a surface of slabs or concrete and only with the recommended base plinth. You may be charged for accessories Installation is for the Greenhouse only and does not include staging, accessories etc

Greenhouse Size Diagram

Greenhouse Dimensions

A: Greenhouse width

2360mm (7′ 8″)

B: Greenhouse depth

3830mm (12′ 6″)

C: Ridge height

2700mm (8′ 10″)

D: Eaves height

2040mm (6′ 8″)

E & F: Door Size

1400mm (4′ 7″) x 2000mm (6′ 6″) (aperture)

Minimum Base Size

2360mm (7′ 8″) x 3830mm (12′ 6″)

Palram Silver Steel Base
Included with ALL Janssens Greenhouses.

The Janssens Foundation Base eliminates the need for a full concrete foundation. Simply assemble your greenhouse and secure it with our quick 4-corner anchoring system!

Premium 4mm Toughened Glass

JANSSENS delivers superior protection with our full-length 4mm toughened glass. Six times stronger than ordinary glass, it offers exceptional durability and safety. Enjoy crystal-clear views and peace of mind, knowing you're shielded by the industry's safest greenhouse glass. Polished edges ensure easy, safe assembly, letting you focus on what truly matters – your thriving garden.

Janssens Glazing Gasket
Weather-Tight Seal: Superior Protection Guaranteed

Don't let wind effect your investment with Janssens state-of-the-art glazing system. Featuring:

  • Advanced rubber strip technology
  • Unbeatable water and wind resistance
  • Seamless, long-lasting seal
Janssens Glazing Bars
Industry-Leading Strength in Every Frame

Janssens cutting-edge tubular aluminium glazing bars are among the sturdiest in today's greenhouse market. Enjoy peace of mind knowing your investment is protected by top-tier materials that outlast and outperform the competition!

Janssens Roof Ridge Profile
Built to Last: Premium Stainless Steel Hardware

Every bolt, nut, and fitting in your JANSSENS greenhouse is crafted from top-quality stainless steel to withstand the elements,

Janssens Roof Ridge Profile
Smart Water Management System Included

Maximize your growing potential with our comprehensive water control solution:

  • Efficient gutters to collect rainwater
  • Clever condensation channels to manage humidity
  • Large 40mm downpipes for rapid drainage
Janssens Instructions
Effortless Assembly at Your Fingertips

Set up your new greenhouse with ease. Every model includes:

  • Detailed step-by-step manual
  • Comprehensive assembly video
Janssens Qualicoat Powder Coating
Lasting Beauty: Premium Powder-Coated Finish

Janssens only use Qualicoat-certified powder coating on all of their Greenhouse products. This high-quality finish ensures your JANSSENS greenhouse stays stunning for years. Contact us for custom RAL colours.

Janssens Greenhouse
Janssens Greenhouses

Janssens Greenhouses were established in 1946 in Lier, Belgium and is now a super modern 6500sqm production facility equipped with the very latest high-tech automated machinery. Many years of production and the very latest design and manufacturing processes make a Janssens Greenhouse one of the best high end greenhouses you can buy today.

Janssens Greenhouse 13 Year Warranty
13 Year Warranty

Janssens greenhouses come with a 10-year warranty on the greenhouse frame. This warranty covers any manufacturing defects in materials or workmanship. However, it does not cover glass or polycarbonate. The warranty is only valid if the greenhouse is assembled according to the provided instructions.