House Extensions in Fulham: Single-Storey, Side Return and Loft Compared

Most Fulham house extensions come down to three options: single-storey rear, side return, or loft conversion. Each adds different square footage, costs different money, and triggers different planning hurdles on an SW6 terrace. Here's how to choose between them.

The three extension types that work on a Fulham terrace

1. Single-storey rear extension

What it is: extending the back of the house out into the garden, usually full width, replacing the existing rear addition with one open-plan kitchen-dining space. Adds 15–25m².

Planning: usually permitted development under the larger home extensions rules (up to 6m projection on a terrace), unless the property is in a conservation area, has Article 4 restrictions, or the neighbour objects to the prior approval notice. Allow 8–10 weeks for planning even if straightforward.

Best for: families wanting a proper kitchen-dining-living space, opening onto the garden. The single biggest quality-of-life uplift you can buy on a Fulham terrace.

2. Side return extension

What it is: filling in the dead alleyway running down the side of the rear addition, widening the back of the house from 2.5m to ~4.5m. Adds 6–12m² and — more importantly — makes the existing rear room properly usable.

Planning: usually permitted development. Party wall agreement always required with the neighbour you're building against.

Best for: terraces with a narrow, useless rear kitchen that you'd rather widen than rebuild entirely. Often combined with a full rear extension for the L-shape.

3. Loft conversion

What it is: converting the unused roof space into one or two bedrooms, often with an ensuite. Adds 20–40m² depending on type (rear dormer, L-shaped dormer, mansard).

Planning: rear dormers usually permitted development; mansards almost always need full planning permission. Conservation areas restrict everything.

Best for: needing more bedrooms, not more living space. If the family is growing but the downstairs already works, a loft adds the most usable rooms per pound.

How to choose between them

Ask one question: what does the house actually lack? More living space? A rear extension. More usable living space without changing footprint? A side return. More bedrooms? A loft.

What's the same across all three

• Party wall agreement with at least one neighbour, usually both. Start 6 weeks before breaking ground.
• Structural engineer calculations for steels. Don't accept a "design included" quote that skips this.
• Building control sign-off at multiple stages — not just the end.
• Scaffolding licence from Hammersmith & Fulham (3–10 working days).
• Skip permit for the duration.

What's missing from cheap quotes

The "all-in" quotes that look cheaper than the others usually leave out:

• Party wall surveyor fees (both sides if you've got two party walls)
• Structural engineer
• Building control fees
• Redecoration of the rooms affected (you'll be replastering and repainting either way)
• Kitchen fit-out (often quoted as "kitchen by others")
• Underfloor heating, second-fix electrics beyond basic spec

Get every quote on the same scope before comparing. Cheapest line item isn't cheapest job.

Local planning quirks worth knowing

Conservation areas (Hurlingham, Moore Park, Bishop's Park, Walham Green) strip back permitted development rights. Article 4 directions in parts of SW6 do the same on a more granular basis. Leasehold flats need landlord consent for any external alterations — always slower than freehold houses. Check both before assuming a project is straightforward.

Call Fulham BM for a fixed-quote extension consultation. 20+ years on SW6 terraces, FMB and CHAS accredited. Request a quote at fulhambm.co.uk.