In many cases, a house extension may fall under permitted development and not require full planning permission. However, this depends on factors such as the size, location and design of the extension, as well as whether the property has been extended previously.

Local councils across Surrey and London will also consider the impact on neighbouring properties, including loss of light, overlooking and overall scale.

I review each project at an early stage and advise whether planning permission is required before preparing any drawings.

The 45 degree rule is a guideline used by many planning authorities to assess how a proposed extension might affect light to neighbouring properties.

A line is drawn at 45 degrees from the centre of the nearest window of a neighbouring habitable room. If the extension crosses this line, it may be considered to have an impact on daylight or outlook.

Many extensions however, are still approved depending on the overall design, building orientation and context.

The cost of a house extension in Surrey in 2026 can vary depending on size, specification and complexity.

As a rough guide:

• Single-storey extension: £2,200 – £3,000 per m²

• Two-storey extension: £2,000 – £2,700 per m²

Higher-end projects or complex designs can exceed these ranges.

I always recommend developing a clear design first, as layout and structural decisions can have a significant impact on overall build costs.

A typical planning application will include existing and proposed drawings such as floor plans, elevations and a site plan.

Depending on the project, additional documents such as a design and access statement may also be required.

I prepare all planning drawings and submit the application on your behalf, managing the process through to a decision.

Most householder planning applications take around 8 weeks from submission to decision, although this can vary depending on the local authority and complexity of the proposal.

Before submission, I usually allow a few weeks to develop the design and prepare the drawings.

Overall, the process from initial concept to decision typically takes a couple of months.

For most house extensions, loft conversions and home renovations, an architectural designer can provide all the services required, including design, planning drawings and building regulations drawings.

I offer a full residential design service, guiding clients from initial ideas through to construction.

The most important factor is choosing someone with the right experience for your type of project.

I offer a full range of architectural design services across Surrey and London, including measured surveys, concept design, planning applications, building regulations drawings and 3D architectural visualisations.

I can be involved throughout the entire process, from initial ideas through to working alongside builders during construction.

Yes, I design loft conversions across Surrey and London, including dormer, hip-to-gable and rooflight conversions.

I can advise on permitted development rights, planning permission requirements and prepare all necessary drawings for both planning and building regulations.

Yes, I can recommend builders where appropriate or work alongside a builder you have already chosen.

I often stay involved during the construction stage to answer questions, clarify drawings and help ensure the design is delivered as intended.

Yes, I produce detailed 3D architectural visualisations to help you fully understand the design before construction begins.

These are particularly useful for house extensions, loft conversions and internal reconfigurations, allowing you to visualise the space and make informed decisions early in the process

I am based in Effingham, Surrey and work with homeowners across Surrey including Bookham, Horsley, Guildford and Cobham, as well as projects in London.

The first step is usually an informal conversation about your project and what you are hoping to achieve.

From there, I can advise on feasibility, design options and whether planning permission is likely to be required, before moving into the design stage.