ALTON TWELVE Greenhouse Ultimate Package With Aluminium Bar Capping


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Home Evolution Twelve Cedar Greenhouse
Evolution Twelve Cedar Greenhouse

N.b. This greenhouse comes with Cedar bar cover capping as Standard. Aluminium cover capping in the moss colour is an optional upgrade. Gutters, base, and other aluminium components come in moss powder coated aluminium as standard.

The clever design of these new Alton Evolution models has created a cedar greenhouse that is ideal for modern needs, and by using innovative and strong jointing technology, the Evolution models are delivered flat packed in a self-assembly format. This removes a large amount of cost from the double handling and storage of large unwieldy glazed panels used on other models, and put simply this allows us to put more wood into the greenhouse.

The result is an extremely strong, high quality cedar greenhouse, designed to be maintenance free- even with the standard cedar bar capping. If you upgrade to the moss coloured aluminium bar capping system you will combine all the benefits of cedar and all the advantages of Aluminium in one hybrid greenhouse.

The best type of wood – and more of it!

The frame is made from Canadian Western Red Cedar, which is extremely high in natural preservative oils which, even without further artificial treatment, make it virtually immune from decay. Cedar also has a unique subtle aroma which can deter pests. The frame is based on mostly planed 2×2 (44x44mm) and 3×2 (69x44mm)

We factory treat your Alton Evolution greenhouse in a clear treatment – thus not masking the natural colour variation of the cedar wood. In time, your greenhouse will mellow into a silvery colour which is so distinctive to cedar. The Moss colour of the metal components is designed to blend in perfectly with this mature silvery colour.

– A metal base keeps the wood well away from the damp area on the floor

– Louvres and Automatic roof vents are standard.

– High Eaves – often overlooked by greenhouse buyers, but it is important to consider. High eaves means the greenhouse feels a lot bigger, and it is far more comfortable for you to work in.

– The guttering and downpipes are included as standard.

– Glass overlaps at eaves, protecting a vulnerable area of your greenhouse from rot.

Other features and options
Mortice joint
Mortice and tenon joints.The Cleverly designed jointing system on the Evolution has the duel benefit of making assembly straight forward and adding strength to the framework.

Aluminium base – This keeps the wood well away from the base where water can sit. Plus this unique design feature allows the glass to sit directly onto the metal base – which means that the side water is not running onto the wood, (which is a ‘rot-spot’ on other greenhouses) The Metal base is included on every Evolution model, regardless of which kind of capping you choose.

gutters and downpipes
Guttering Takes the water away and allows you to collect it. Included on every model regardless of which kind of capping you choose.

Door theshold
Roof vents. A generous allocation of roof vents is included with every model and every roof vent has an automatic opener included as standard. These clever devices work through heat expansion alone to open your roof vents gradually as the temperature changes. Fully adjustable, they help you to create the perfect growing environment.

Louvres Your new Alton Evolution model will also include one or more louvre windows. These work in tandem with your roof vents – as the automatic roof vents open and release the warm air, the greenhouse effectively sucks air in through the louvres. These can be positioned near the bottom or the top and on most models at the side of the greenhouse or at the rear. Supplied as manual opening as standard and you can add automatic louvre openers if you wish.

Door theshold
The unique Alton Evolution door system includes the low-profile door threshold. This popular feature means that you have no step at the door (many other greenhouses have a step at the door). Models of 8′ wide and above have 4′ wide access double doors which allow easy entrance for a wheelbarrow or wheelchair.

Aluminium bar capping
Upgrade option Aluminium bar capping – With this new Aluminium bar capping system you really can have a virtually maintenance free Cedar greenhouse – and the stylish moss colour blends in perfectly with the cedar as it ages to the distinctive silvery colour.

Door theshold
The eaves height of 5’7″ on the Alton Evolution models is excellent and is as much as 18″ higher than the lowest greenhouses on the market. The extra height gives you several advantages: There is more air in the greenhouse creating a better growing environment, you have more head room and a higher door, and you have plenty of room for a high level shelf in the greenhouse.

* The Ultimate Package includes an upgrade to aluminium bar capping from the standard cedar capping, aluminium shelving and staging in moss green to length, down one side.

Additional information




Cedar Wood

Measurements Metric

3877mm x 1977mm to 3877mm x 6347mm, 3877mm x 1977mm, 3877mm x 2606mm, 3877mm x 3236mm, 3877mm x 3866mm, 3877mm x 4496mm, 3877mm x 5087mm, 3877mm x 5756mm, 3877mm x 6347mm, 3877mm x 2520mm

Measurements Imperial

12'9" x 6'6" to 12'9" x 20'10", 12'9" x 6'6", 12'9" x 8'6", 12'9" x 10'7", 12'9" x 12'9", 12'9" x 14'9", 12'9" x 16'8", 12'9" x 18'10", 12'9" x 20'10", 12'9" x Ex TENSION 8'3"

Estimated Delivery

4 weeks

Guarantee Length

10 Years

Installation included


Delivery cost included


Made in



12'9" x 6'6"- (7.66 m2), 12'9" x 8'6"- (10.10 m2), 12'9" x 10'7"- (12.55 m2), 12'9" x 12'9"- (14.99 m2), 12'9" x 14'9"- (17.43 m2), 12'9" x 16'8"- (19.72 m2), 12'9" x 18'10"- (22.32 m2), 12'9" x 20'10"- (24.61 m2), 12'9" x Ex TENSION 8'3"- (9.77 m2)