Guildford is a borough where the setting does a lot of the deciding. The same rear extension can be straightforward on a 1930s street in Merrow and a careful piece of negotiation on a cottage in Shere. This guide sets out how Guildford Borough Council judges householder applications, which documents it uses, and what to think about before you spend money on drawings.
From 1 April 2027, Guildford Borough Council is replaced by the new West Surrey Council, which takes over planning across Guildford, Woking, Waverley, Surrey Heath, Runnymede and Spelthorne. Guildford’s existing plans are expected to carry across until the new council adopts its own, and a permission you already hold stays valid. Our West Surrey page explains the change.
The plans your application is judged against
Guildford’s development plan comes in two parts, with a design guide alongside.
- Local Plan: Strategy and Sites (2019). Adopted on 25 April 2019, this is the borough’s main plan, covering the Green Belt, housing and the big strategic decisions.
- Local Plan: Development Management Policies (2023). Adopted on 22 March 2023, this adds the detailed policies officers use on everyday applications. Policy H4, on housing extensions and alterations including annexes, is the one that applies to most householder schemes.
- Residential Extensions and Alterations SPD (2018). The council’s design guide for extensions, roof alterations, dormers and outbuildings. It explains what Policy H4 means in practice, with diagrams.
The council agreed a timetable for a new local plan in February 2025. For now, and until West Surrey Council writes its own, the documents above are the ones that count.
What Guildford looks for in an extension
The extensions guide boils down to a few questions an officer will ask of your drawings.
Does it respect the original house? Extensions should look subordinate to the house: lower ridge lines, set back from the front, with matching or deliberately complementary materials. A two-storey side extension that runs flush with the front and the ridge is the classic thing the guide steers you away from.
Does it keep the gaps in the street? In many Guildford roads, the spaces between houses are part of the character. Side extensions that close those gaps at first floor are often refused. Setting the upper storey back from the boundary is the usual answer.
What does it do to the neighbours? Daylight, outlook and privacy matter here as everywhere. Deep extensions on a shared boundary, and first-floor windows or balconies that overlook gardens, are the commonest problems.
Is the roof work in keeping? Dormers should sit within the roof slope, below the ridge and set in from the eaves and sides. Large flat-roofed box dormers facing the street are rarely accepted.
The setting: Green Belt, Surrey Hills and conservation areas
Green Belt. A large part of the borough beyond the town is Green Belt, including most of the villages. Extensions there are judged on whether they are proportionate to the original building, meaning the house as first built, or as it stood in 1948 if older. Earlier additions count against what you can add now.
The Surrey Hills National Landscape. Much of the south and east of the borough, including the Tillingbourne valley around Shere, Gomshall and Chilworth, sits in the Surrey Hills National Landscape. Permitted development rights are narrower there, and the council looks closely at scale, materials and how an extension sits in views from the hills.
Conservation areas. Guildford has around 40, from the town centre and the Millmead and Portsmouth Road area to villages such as Shere and Ripley. In a conservation area, permitted development is reduced, materials and detailing matter more, and you will usually need a short heritage statement with the application. Listed buildings need listed building consent as well.
Thames Basin Heaths. Parts of the north and west of the borough are close to the protected heathland of the Thames Basin Heaths. An ordinary extension is not affected, but a project that creates a new home, such as an annexe let as a separate dwelling, brings extra requirements.
Permitted development in Guildford
Some extensions can be built without a planning application, within national limits. As the rules stand in late 2026:
The main permitted development limits for a single-storey rear extension, as they stand in late 2026. Diagram: James Williamson Architects.
- a single-storey rear extension up to 4 metres deep on a detached house, or 3 metres on other houses, needs no prior approval;
- deeper single-storey rear extensions, up to 8 or 6 metres, can go through prior approval;
- a loft conversion can add up to 40 cubic metres on a terraced house or 50 cubic metres on others, with no dormers on the road-facing slope;
- a single-storey side extension can be up to half the width of the original house.
In conservation areas and the Surrey Hills, side extensions and roof extensions lose their permitted development rights, and cladding is restricted. That covers a lot of Guildford. Many newer estates also had their rights removed by planning condition. A lawful development certificate is the safe way to confirm the position. Is a double dormer loft conversion right for you? covers the loft rules in more depth.
Making an application in Guildford
Pre-application advice. Guildford Borough Council offers a paid pre-application advice service. Check the current fee and process on the council’s website. It is most useful where a scheme sits in the Green Belt, a conservation area or the Surrey Hills and the principle is uncertain.
Validation. Applications must meet national requirements and the council’s local list. In a conservation area or near a listed building, include a heritage statement. In the Green Belt, a short calculation of the original and proposed floor area or volume helps the officer judge proportionality, and it saves a round of questions.
Timescales. The statutory target for a householder application is eight weeks from validation. Listed building consent, often needed in the older parts of the borough, runs alongside on a similar timescale.
Our work in Guildford
Two recent Guildford projects show the range. For a family home, every builder had suggested knocking through and extending into the garden. We replanned the ground floor instead: a better kitchen with a hidden utility, the dining room opened to it, and the front room back to being a snug. The scheme was smaller than anything the builders had proposed. For a townhouse with nowhere to go but up, we turned the attic into a main bedroom suite, a home office and built-in storage, with dormers and rooflights within the limits set by the existing roof.
The Guildford townhouse loft conversion.
There is more on our Guildford page, and in our guides to house extensions in Guildford, kitchen extensions in Guildford and loft conversions in Guildford.
The houses we see most often in Guildford
Townhouses and terraces near the centre. Around the town centre, Stoke and the streets near the Mount, Victorian and Edwardian houses have little room to grow sideways. The roof and a modest rear or side-return extension are usually the options, and conservation area rules often apply.
Interwar and post-war semis. In Merrow, Burpham and Onslow Village there is often room at the back and side. These are the houses where a single-storey rear extension under permitted development, or a well-judged two-storey side extension, can make the biggest difference.
Cottages and village houses. In Shere, Gomshall, the Clandons and the Horsleys, older houses often sit in a conservation area, the Surrey Hills or the Green Belt, sometimes all three. Here, careful design and good materials matter more than square metres.
After planning: the steps people forget
Planning permission is only the first approval. Before building starts you will also need:
- Building regulations approval. This covers structure, fire safety, insulation, ventilation and drainage. You can use the local authority building control service or a registered building control approver. Planning drawings are not enough to build from: the structure, the details and the specification need working out first.
- Party wall agreements. If the work involves a shared wall, or digging foundations close to a neighbour’s, the Party Wall etc. Act 1996 requires you to serve notice on them. Leave time for it, because a neighbour can take several weeks to respond.
- Planning conditions. Many Guildford permissions come with conditions, such as matching materials or obscured glazing to side windows. Some must be discharged before work starts.
Sorting these in the right order is what keeps a project on programme once the planning decision arrives. Planning permission vs building regulations explains the difference.
How we approach a Guildford project
We start by finding out which layers of protection apply to your plot: Green Belt, Surrey Hills, conservation area, listed building, or none at all. That alone changes what is realistic. We then read the planning history, test the scheme against Policy H4 and the extensions guide, and look at what the council has approved and refused nearby.
Usually one move carries most of the risk: a side extension at first floor, a large dormer to the street, or the size of an addition in the Green Belt. Once that is clear, you can change it, keep it and build the case for it, or phase the work so the certain part goes first. The Clarity Pack does exactly this before design, alongside the structure and the likely cost bands.
Questions people ask about planning in Guildford
Which policy covers house extensions in Guildford? Policy H4 of the Local Plan: Development Management Policies, adopted in March 2023, supported by the Residential Extensions and Alterations SPD of 2018.
Can I build a dormer in Guildford without planning permission? Sometimes, on a house outside a conservation area and the Surrey Hills, if the dormer is to the rear and within the volume limits. In protected areas, roof extensions need planning permission.
How much can I extend a house in the Green Belt? There is no fixed percentage in law. The test is whether the addition is proportionate to the original building, and the council looks at the cumulative effect of earlier extensions.
Will West Surrey Council change Guildford’s rules? Not straight away. Guildford’s plans are expected to carry across until the new council adopts its own, and existing permissions stay valid.
Where to start
The free 15-minute Clarity Call is the first step. We’ll talk through your home, where it sits in Guildford’s planning layers and whether the Clarity Pack would help. For the general rules, see do I need planning permission for an extension? The same guide exists for every Surrey borough we work in: see all eight planning guides.
