Glazing guide: Double height glazing with XP Slide Panoramic doors from Express Bi-folding Doors

Oversized glazing: a buyer’s guide

A guide to glazing that enhances the look of your home and performs brilliantly

By Caroline Rodrigues | 28 February 2022

Bright interiors, great views and an easily accessible connection with the garden are some of the benefits of fitting glazed doors. To tempt you with ever more exciting design possibilities, glazing manufacturers continue to innovate and offer larger glass panels. Structurally bonded sliding doors are one of the most recent introductions.

‘The frames are bonded to the glass so can be extremely narrow. With some systems the outer frame is completely concealed so the doors look like a glass wall,’ says Steve Bromberg, managing director of Express Bi-folding Doors.

Will I need permission?

Many glazing projects won’t need planning permission but there’s no hard and fast rule. ‘It will depend on the type of property, where it is, whether you are replacing like for like, and if there are any specific restrictions in place,’ says James Davies, director of Paper House Project.

‘Your choice of door may be restricted if you are in a Conservation Area. When a building is listed you must consult an architect, planning or heritage consultant as well as your local authority,’ James continues. Check with your local planning department or visit the Planning Portal. Both replacement and new door design installations will need to meet Building Regulations.

Large aperture double height glass doors with XP Slide Panoramic doors

This huge rear extension in West Yorkshire features a double-height glazed facade with XP Slide Panoramic doors from Express Bi-folding Doors

The buying process

Visit several showrooms if you can, to see different glazed door types and configurations. To get an estimate, take along approximate measurements, architects’ drawings, and photos of your site. Once you’ve pinned down the style, glass, configuration, security and frame option, a formal quote will be sent out. You can expect a surveyor from the company to visit the site, and to get detailed drawings.

‘A reputable supplier will liaise with your chosen builder and/or architects to iron out any of the technical details,’ says Tony Culmer, managing director of Maxlight. ‘Once you are happy with everything, expect an eight-week wait for delivery, then allow two to three days for installation – complex projects can take longer,’ he adds.

Terrace house extension with fixed glazing and casement doors

This extension to a Victorian terrace in London by Sinclair Studios has Mondrian steel-framed fixed glazing and casement doors using IQ Glass. Photo: Luke Weller

Thermal efficiency

Large glazed doors can be a weak point in the insulation envelope of your home. ‘Look for the whole door U value, which includes both the thermal efficiency of the frame and the glazing,’ says Chris Herring, director of Green Building Store. You’ll find this information on door supplier websites, as W/m2K – Watts per metre-Kelvin. The lower the value the more thermally efficient the product. Typically, triple-glazed timber whole door U values range from 0.95 to 0.75 W/m2K, while double-glazed U values are in the region of 1.4 W/m2K.

‘Choose doors with the highest level of airtightness, which is indicated by a Class 4 rating. I also recommend using quality airtightness tapes around the door frames,’ Chris adds. ‘Heat can escape from your home via thermal bridging where different materials meet, such as timber frames against stone or brick walls. This wastes energy and leads to the risk of condensation and mould on these cold areas. To minimise thermal bridging, it is often possible to create an insulated threshold detail. Thermal modelling software is used to establish the thermal bridge Psi values – a measure of heat loss along a junction between two elements.’

Velfac glazing on a Victorian terrace extension in London

Paper House Project rebuilt an existing lean-to and added a side-fill extension to this London home with tailor-made Velfac 200DGU doors. The frames are aluminium on the exterior and timber on the inside. Photo: French + Tye

Weather-proof and secure

Good drainage is vital to keep rainwater out of your home. A level threshold system, where the floor levels are the same and the drain sits beneath appears seamless. The alternative is a weather-tested threshold with a protective upstand. In either case, ensure the patio slopes away from the house to direct water away.

Keep home security up to scratch with multi-point locking and a hidden in-line tracking system to prevent the doors being lifted from their mechanism. Locks should comply with the police-preferred Secured By Design standards.