Swallow Heron 20x8 ThermoWood Lean To Greenhouse and Installation

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The imposing Heron 20ft x 8ft wide Lean To greenhouse will be a superb acquisition for any gardener who is serious about growing a wonderful range of plants and produce.  

Designed and built by craftsman in a traditional style, the lean to has marvellous qualities due to Swallow's use of ThermoWood®. They only greenhouse manufacturer to use this heat treated timber that is highly resistant to both warping and decay.

You will benefit from the greenhouse's extended lifespan and the fact there is no need to apply expensive preservatives due to the resilience of the wood.

On entering the lean to through large double doors that are fitted with a mortice lock, you'll notice immediately the excellent growing conditions. Four roof vents create a refreshing flow of air and they open automatically to regulate temperature and humidity.

In addition to the standard toughened glass, there's staging fitted along one side with the option of adding more. Other options include a high shelf and a rainwater collection system to aid re-cycling.

Tremendous structures such as this lean to will enhance your property as well as your gardening, and delivery with installation is included in the price.

20x8 Heron Lean To Features:

  • ThermoWood®: Heat treated Scandinavian timber that's rot and warp resistant
  • Glazing: 3mm Toughened safety glass
  • Roof Vents: Four with auto openers
  • Staging: On one side (L shape optional extra)
  • Doors: Double installed as standard
  • Glazing Bars: 58mm x 34mm finished size
  • Bottom Tongue & Groove: 12mm boards, 390mm long
  • Locks: Door has a mortice lock & aluminum handles
  • Glazing: All glazing is slid into a groove & sealed with quality silicone
  • Joints: All the cut shapes are jointed with a clear plastic H section
  • Capping: The ridge and top vents are sealed with a specially machined timber capping
  • Damp Barrier: 20mm black PVC section screwed to the bottom
  • Stainless Steel Nails: Used to fix all the tongue/groove boards
  • Delivery and installation included in price

20x8 Heron Lean To Dimensions:

  • Gable width: 2640mm (8ft 8ins) 
  • Length: 6360mm (20ft 10ins)
  • Eaves height: 1730mm (8ft 4ins) 
  • Ridge height: 3260mm (10ft 8ins)
  • Door width: 1200mm (3ft 11ins)
  • Door height: 1980mm (6ft 6ins)

Note: A smaller 18ft x 8ft version of this Lean To greenhouse is available.

Optional Extras for your Swallow Greenhouse

Staging along one side is included as standard in your Swallow GB Greenhouse, however, an additional High Level Shelf and Extra Staging on the end to make an L shape is an option below and can also be painted in a colour to suit. The Hunter Gutter and Downpipe Kit allows you to collect and reuse rainwater - the best water for all plants - this is available as an optional extra below.

Please Note: Imagery may show Dove Lean To's of a different size and optional extras that must be purchased separately. A suitable flat, level and sturdy base must be prepared before the delivery / Installation date to ensure a hassle free installation.

Select Your Options

Additional Accessories for your Greenhouse

  • with Ornate Black Door Handle


Build Design - Please Choose Your Required Door Position

  • with Door on the Left Side

  • with Door on the Right Side

Option 1: Would you like your Greenhouse Painted?

  • with Standard ThermoWood® Finish

  • with ThermoWood® Finish in BRACKEN


  • with ThermoWood® Finish in OLIVE


  • with ThermoWood® Finish in EARTH


  • with ThermoWood® Finish in LILY WHITE


Option 2: Would you like to add Extra Staging?

  • with ThermoWood® Extra Staging


Option 3: Would you like to add a High Level Shelf?

  • with ThermoWood® High Shelf


Option 4: Would you like to add a Rainwater System?

  • with Swallow Hunter Rainwater System in WHITE


  • with Swallow Hunter Rainwater System in BLACK


Option 5: Please choose a Delivery option -

  • including Delivery/Installation within Mainland UK

  • including Delivery/Installation within Scotland (North of Grangemouth)


Delivery Info


Inclusive delivery and installation is limited to UK Mainland excluding areas 15 miles further North of Glasgow. Areas further than this and Offshore Islands would require a custom quote. Please Contact Us here if this is the case.
A suitable, flat and level base must be prepared prior to the delivery and installation.

Price Promise

If you find any of our products in stock and immediately available, at our competitors we will try out best to match the price. We do not charge extra for delivery or installation, but if you find somewhere cheaper, please Contact Us so that we may try to match the price or beat it.


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£4,067.00 inc. VAT