House extension architect in Guildford

Guildford is a borough where the setting does a lot of the deciding. A large part of it is Green Belt, much of the south and east sits in the Surrey Hills National Landscape, and there are around 40 conservation areas. An extension that would go through without comment in one street can be refused in the next. Knowing which rules apply to your house, before anyone draws anything, is most of the battle.

We are based in Woking and work across Guildford, from Stoke, Merrow and Burpham to the Clandons, the Horsleys and the Tillingbourne villages. This page is about extensions. For the wider picture of planning in the borough, see our Guildford architects page.

The three layers behind every Guildford decision

The local plan. Guildford’s development management policies, adopted in 2023, include specific policies on house extensions, design quality and the amenity of neighbours. They carry full weight.

The design guide. The Residential Extensions and Alterations guide, adopted in 2018, goes through front, side, rear and roof extensions. Its central test is subordination: an extension should step down from the main roof, sit back from the front of the house and use materials that belong.

The setting. In the Green Belt, extensions are judged on whether they are proportionate to the original building. In conservation areas and the Surrey Hills, permitted development rights are narrower and the council looks harder at materials and views.

An application that answers all three on paper is one the planning officer can support. One that ignores any of them usually comes back.

Rear, side or two-storey?

Single-storey rear extensions are the most common. Many can be built under permitted development, up to 3 metres deep on a terraced or semi-detached house and 4 metres on a detached one, or up to double that through prior approval. In the Green Belt, even a permitted development extension counts towards the proportionality test for anything you add later.

Side extensions are where the design guide is most specific. Expect to set a two-storey side extension back from the front wall and drop its roof below the main ridge, so the original house still reads clearly and the gaps between houses survive.

Two-storey extensions give the most space for the money, and need the most care with neighbours’ light and privacy.

What it looks like done well

Just up the road in Woking, we designed a two-storey side and rear extension for a one-bedroom end-of-terrace, taking in an old lean-to garage and turning it into a three-bedroom family home. It steps back and down from the original house, which is exactly the approach Guildford’s guide asks for, and the stair and walls are drawn so a loft can follow later.

The Woking starter home extension, a two-storey side and rear extension.

At a detached house in Hook Heath, the slope of the plot made room for a new lower ground floor opening onto the garden, adding a whole floor with barely a change from the street. On sloping Guildford sites, around the Mount or towards Shalford, the same idea is often worth exploring.

Sometimes you do not need to extend

In Guildford itself, Jeremy and Mary-Jane were told by every builder to knock through and extend into the garden. The real problem was how the ground floor connected, not its size. A replanned kitchen, dining room and snug gave them the house they wanted, smaller than any of the builders’ schemes and finished months sooner. That project is on our kitchen extension architect in Guildford page.

The Guildford kitchen and ground floor renovation.

Where to start

The free 15-minute Clarity Call is the place to start. If there is something worth testing, the Clarity Pack works through what your house can realistically take, the planning position with Guildford Borough Council, the structure and the likely cost bands, before you commit to drawings or builders. Our pages on single-storey extensions, double-storey extensions and heritage and conservation go into more detail.