Granny Flat Prices in London

Granny flat prices in London start from £4,500/job. A 1-bedroom granny flat costs £98,000 on average. Prices include VAT. Garden annexes typically require planning permission unless they qualify as permitted development. Build times vary from 8–16 weeks depending on size and complexity.

The best granny flat type depends on your budget, lot size, and intended use. For rental income, a 1-bedroom or 2-bedroom with standard finishes offers the best return on investment. For family use, consider accessibility features and a more generous layout.

A standard granny flat in London takes 12–20 weeks from slab to handover. A 2-bedroom build averages £144,000 and takes 16–20 weeks. Kit/prefab builds can be completed in 8–12 weeks. Council approval adds 2–24 weeks depending on the pathway.

Yes — all granny flats in London require building or planning approval. Your builder or certifier will advise on whether you can use a fast-track approval pathway or need a full development application. The approval process, costs, and timeline vary by council area.