Should you choose a traditional or contemporary home extension?

Even rough-finish exposed concrete, the signature of the 20th-century modernist architects, requires the back-up of a highly advanced construction industry. When we see this kind
of building, we are subconsciously aware that it is well beyond the skills of craftsman working alone and so associate it with our contemporary world.

Many of the design techniques are borrowed from up-market retail, office and hotel buildings, lending an air of class and luxury along with a very un-domestic character.

Glass boxes extensions, such as this one by IQ Glass, can feel more like a part of the garden than the house, and frameless styles are so minimal that they do not clash with the character of the existing dwelling

The disadvantage of having prefabricated components is the cost. The vast majority of smaller building companies in the UK are used to using traditional, on-site construction methods and are suspicious of the precise assembly that is essential for success, which means they will increase their prices to cover the perceived risk.

The products themselves are also more expensive, not least because many of them are shipped in from other countries.

In keeping or contrasting design?

Your preference may be to add a contemporary extension to a traditional house, but there are several factors to consider.

A key strategy is to create a stark contrast with the existing building. As the new element is so different, we read the style and form of new and old completely separately. Using contrast in this way can be so successful that some of the most attractive modern extensions are additions to listed properties.

But half measures do not work here – hence a brick extension built with traditional detailing but with a modern flat roof looks clumsy.

The more skill and craftmanship that has gone into the existing house and the more heritage value it has, the more expensive it is to add authentic traditional details.

Oakmasters created this successful extension to a listed half-timbered house. The double-storey addition is a traditional oak frame structure with internal trusses and open vaulted ceilings

This is because, barring great expense, the result is likely to be a pale imitation of the original in a way that will be brutally exposed when the two are seen together. So there is a very good argument that a building of historic quality should be enlarged with the most up-to date-design possible. Interestingly it is rare for a traditionally styled extension to be added to an existing modern home.

If you prefer something more in-keeping with the style of the house, provided that it is a typical suburban building, this will be relatively cost effective and straightforward.

You will find plenty of builders willing to price the work competitively and it may be a simple matter to replicate the existing details. Many people take this route and although the result can sometimes be rather ‘vanilla’ it’s perfectly satisfactory, particularly if the budget is tight.

A modern extension can experiment with unusual materials and forms. Architects Office S&M’s addition to a London terrace uses a spray-on Prokol polyurea liquid membrane exterior finish [Credit: French & Tye]

However, it can look wrong if the new work is poorly designed. For example, a classic Arts & Crafts house has clay rosemary roof tiles that have to be set at a pitch of 35° or more. The angle of the new roof can’t be lower and if the span is too wide it would be disproportionately high.

A roof with a large span has to be very shallow to avoid this problem, which is only possible using modern concrete interlocking tiles, resulting in a shape and appearance that is completely different to the original.

In this kind of situation, a modern flat covering with rendered walls and steel-framed windows may be a better-looking option.

Typical planning policies

Not so long ago, many planning departments would insist that any extension to a traditional looking house was of a similar style. Anything that was different was summarily dismissed as ‘incongruous’. I never heard a satisfactory explanation from planners as to why this very subjective view should lead to an automatic rejection.

Fortunately, many planning departments have since changed their policy and now actively encourage contemporary design.

This current popularity is partly due to the fact that the authorities now have a better understanding of how these buildings will look and consider them acceptable, even in conservation areas.

Read more: How to get planning permission for an extension

There is a problem with very modern schemes though, which affects some local authority officers and councillors who sit on planning committees. They find it relatively easy to look at elevations showing a traditional extension and can see in their mind’s eye how it will look because the materials and details are so familiar.

The owners of this Victorian property in Buckinghamshire asked Westbury Garden Rooms to create a timber orangery extension. A creamy finish contrasts with the red-brick original

Very creative contemporary designs can look terrible in 2D drawings because they are so unfamiliar.

The real drama and beauty of this kind of look can only be appreciated by visualising it in three dimensions, so to be successful with a planning application you need an architect who can design and present it in a way that will help everyone appreciate how the proposal will look once it is completed.

Main image: The team at OB Architecture based their extension design on sketches of the house from 1863 showing a cluster of pitched roof forms, which have been removed over time.