K2 Portal - A Listed Case

When it comes to designing a portal there is little that K2 hasn’t seen or done.

So when the Windowmakers contacted K2 Architectural enquiring about creating a portal to replace an existing (and aging) Victorian design it was business as usual.

Erik Turner, of Portsmouth based the Windowmakers, explains: “The installation took place in Guernsey, a first for us. The original structure (Vine House) was originally built in 1840 and the whole property, including the greenhouse, is a listed building.


It took over 11 months to persuade the local historical council to let us change the use of the original structure (a greenhouse) and rebuild as an aluminium and glass conservatory.

Their agreement (granted in June 2010) was on the condition that we replicated the original design so that its appearance remained unaltered. It took over a year for the owner to remove the existing timber structure, glass etc…as it had to go to the historical warehouse on the island to be used in other projects.

The original building (shown as a water colour painting done in 1910) had a built in water tank destined to feed the vine. This was removed and the front wall taken down to allow access into the cellar of the house. The cellar will become a new kitchen and the now upper area will become an open plan mezzanine.”

K2’s Tim Burton comments: When Erik Turner approached us with this project, it seemed ideally suited to the K2 portal system’s capability, especially as we have already been approved for many listed building projects.

The overall specifications of the installation are as follows: Overall design: 2 storey installation, lean-to style. Overall dimensions: 6800mm (from internal floor) and 4000mm (from external ground level), width: 9400 mm

System used: the K2 portal system and K2 aluminium roof Key structural components: 10 portal rafters (6500mm long), with the roof bars nearing 7000mm. The eaves, legs and main trusses used the K2 Commercial beam (200mm x 102mm). Side legs use the K2 150mm x 83mm leg and the pearlings use the 165mm x 68mm leg, both from K2’s Compact suite

Fixing: the portal frame is fixed to the house using plate fixes while the rest of the frame is supported using the legs made from our 200mm commercial beams

Options: 6 electric aluminium vents.

Colour is standard white (RAL 9016)

Glazing: The roof and frames are glazed with Celsius Clear, which features a U-Value of 1.0. The larger roof units measure 2790mm x 900mm. Each roof unit was fitted with 25mm Astragal bar – and rubber buffer to prevent sagging - to comply with the Historical Council’s requirements of maintaining the original appearance

The final design includes a mezzanine floor with spiral staircase going down to the garden room, complete with 5m bi-fold doors

K2 Conservatories have been designing portal systems in-house for over 10 years.

They are used on the larger projects, for which a traditional conservatory roof system would not be suitable and a more robust structure is required.

Some of our earlier installations, illustrated here, include pool houses, the Brooklyn Hospital project, and a large canopy for the Ministry of Defence. Some more recent installations include the brand new K2 showroom, the Gisland Spa hotel in Carlisle (part of the Co-operative group), and of course the Vine House installation.


Smaller, residential installations also use the K2 portal, from the unusual to the unexpected.

Portals are becoming increasingly popular. K2 has seen a further surge in demand in 2011. We believe this stems from two key shifts in the market:

A move away from the smaller, polycarbonate glazed products when replacing an existing conservatory, which often requires the use of a portal frame to provide structural integrity;

The growth of the high value market, where owners of prestigious properties see the addition of a “glass room” as a must have, both for its practical side and for real added value.

K2’s design capabilities combined with our unique, patented portal system, makes us the ideal supplier for architectural projects, commercial and residential.

Capital Investment

The installation of a new Optimax system glass cutting table from Hegla was recently completed. Andy Vint, glass production manager, explains that this capital expenditure demonstrates that K2 is committed to continuous improvement and to providing a high quality product.

"This is the most significant investment carried out by K2 for the glass production department and will prove key to the division future's success in remaining competitive"


For more information, click here.

New Literature

K2 are adding yet more literature to their extensive range, and have now made 3 further  "customise" mailers available. They are Customise with Eaves Trim (CUSEAVM), Customise with Colour (CUSCOLM) and Customise with Aluminium (CUSALIM).


We realise that our customers need the best tools to support their efforts to sell high-end products. The introduction of these eye catching pieces will help them do just that. Customers can order in the usual manner.