Garden Annexes (updated)

Yes. Because a garden annexe is intended as habitable, self-contained accommodation — with sleeping, washing and often cooking facilities — it sits outside Permitted Development. Planning permission and Building Regulations approval are both required. Our in-house architectural team will manage the entire application on your behalf, with a current 100% success rate.

Yes, where it's been built to full Building Regulations and has planning permission as ancillary residential accommodation. All our annexes are designed to be lived in year-round — properly insulated, properly heated, and approved as habitable space.

The build itself usually takes six to ten weeks on site, depending on the size and specification. Before that, planning applications typically take 12 weeks from submission. From first enquiry to handover, six months is a realistic estimate for most annexe projects.

As a guide, our bespoke annexe projects typically range from £59,000 to £120,000+, depending on size, specification and the level of planning and Building Regs work required. Because every annexe is individually designed, we don't publish a fixed price list — complete our Project Planner and we'll come back to you with a genuine estimate based on your site and brief.

Industry research, including Checkatrade's, suggests a well-built annexe adds 20–30% to a home's value — comfortably more than a typical kitchen refit or loft conversion. The exact uplift depends on your location, the quality of the build, and how the annexe is marketed at point of sale.

It can, but it's important to tell us upfront if this is the plan. Garden annexes are usually exempt from the Community Infrastructure Levy (CIL) when they're built for family use within the grounds of your main home. Letting the annexe out — including short-term lets and Airbnb — is treated as a "disqualifying event" that can withdraw that exemption, making the annexe liable for CIL, potentially backdated, with a legal duty to notify the local authority within 14 days of the letting starting. If rental income is part of your plan from the outset, we'll factor this into the application and process it accordingly, rather than it catching you out later.