Can I rent out a garden annex?

This depends on your planning permission conditions. Some approvals restrict use to 'ancillary' accommodation for family only, while others permit independent letting. We recommend discussing your intentions with your installer at the feasibility stage.

How much does a garden annex cost?

Garden annexes typically start from £65,000 and range to £120,000+ depending on size, specification, and finishing level. While this is more than a standard garden room, it's significantly less than a traditional extension or buying additional property.

Can I rent out a garden annex?

This depends on your planning permission conditions. Some approvals restrict use to 'ancillary' accommodation for family only, while others permit independent letting. We recommend discussing your intentions with your installer at the feasibility stage.

How much does a garden annex cost?

Garden annexes typically start from £65,000 and range to £120,000+ depending on size, specification, and finishing level. While this is more than a standard garden room, it's significantly less than a traditional extension or buying additional property.

Harefield · Middlesex

Garden Annexe in Harefield

Serving the London Borough of Hillingdon planning area · Uxbridge (Metropolitan & Piccadilly lines) — 4 miles

Self-contained living spaces perfect for guests, family, or rental income. Built to our 2026 Part L standard — adding £25,000–£60,000 to your Harefield property. From £65,000.

0.15 W/m²K

U-value

£25,000–£60,000

Value uplift

25–40 days

Build time

£103

LDC fee

Trusted by homeowners in Harefield

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Matched to Harefield installers who know London Borough of Hillingdon planning requirements.

Garden Annexe in Harefield, Middlesex

Harefield is a village community on the north-western boundary of Greater London, bordered by open countryside, the Grand Union Canal, and ancient woodland. Its semi-rural character and relatively large plot sizes make it an excellent location for substantial garden room builds — with the kind of space that simply doesn't exist closer to the city. Harefield's detached and semi-detached homes frequently sit on plots significantly larger than the London average. This translates to more design freedom, easier ground screw foundation installation, and the possibility of larger structures without touching the 50% garden coverage limit.

Why Harefield Homeowners Choose This Build

Keep family close while maintaining independence and privacy

Cost-effective alternative to care homes or house extensions

Increase your property value significantly

Faster construction compared to traditional building extensions

Potential rental income stream (subject to planning)

2026 Technical Specification

Wall construction150mm SIPs panels

U-value (wall)0.15 W/m²K

GlazingA-rated argon-filled

Acoustic reduction40dB+ standard

Data infrastructureCAT6A (10Gbps ready)

ElectricsPart P compliant

FoundationsGround screws (no concrete)

Build time25–40 days

FSC-certified timber · Ground screw foundations · Just One Tree partner

Planning in Harefield — London Borough of Hillingdon

Harefield is within Hillingdon's planning jurisdiction. Most builds here will be straightforward Permitted Development. The village conservation area around St Mary's Church has limited extent — the majority of residential properties are unaffected. Your installer will confirm your position at the initial site survey.

£103

LDC fee

2.5m

Max height (boundary)

50%

Max garden coverage

London Borough of Hillingdon Portal Full PD Guide 2026

How We Work in Harefield

Feasibility Assessment

Check planning viability, site suitability, and building control requirements for habitable space.

Planning Application

Full management of the planning permission process, including design and submit documentation.

Building Control

Ensuring all regulations for habitable space are met, including fire safety and accessibility.

Complete Construction

Full build including all utilities, plumbing, electrics, and interior finishes.

See Completed Projects Near Harefield

Real builds with specs, materials, and planning routes documented.

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Garden Annexe FAQs — Harefield

Yes. Garden annexes intended for sleeping or living accommodation almost always require planning permission. Our partner installers manage the full application process on your behalf and can advise on the likelihood of approval in your specific borough.

“The team connected me with a fantastic installer who built my garden office in under 10 days. It's warm, quiet, and I love working from it every day.”

Sarah J.

Wimbledon, SW London · Garden Office

“Quick, professional, and totally transparent. I compared three quotes and picked the best one. My music studio is perfectly soundproofed.”

David M.

Highgate, North London · Music Studio