House extensions in Uxbridge and Hillingdon, built at the price you agree

Whether you own a semi-detached house, a detached family home or a bungalow, an extension is one of the most cost-effective ways to gain space without moving. We build single-storey rear extensions, side and wraparound extensions, and double-storey additions, with open-plan kitchen and living space, garden rooms and bi-fold doors. Steel and timber framing, structural engineer coordination and building regulations are all managed for you.

Every property is different, so we do not publish a one-size-fits-all price. As a guide, published 2026 London figures put single-storey extension construction at roughly £3,000 to £5,000 per square metre, before VAT and professional fees, with a new kitchen or bathroom on top. Your own price depends on size, structure, glazing and finish.

After a free site visit you receive a written, itemised fixed-price quote, so you can see exactly where the money goes and compare it fairly with any other quote.

Source note: Cost guide figures from Architecture for London, "How Much Does a House Extension Cost in London? 2026 Update". Guides only; your quote will be specific to your project.

Many single-storey rear extensions in England can be built under permitted development, without a full planning application. The standard limits are 3 metres deep for semi-detached and terraced houses and 4 metres for detached houses, with larger depths of 6 and 8 metres possible through the prior approval route. Height, materials and boundary rules also apply.

Permitted development does not apply everywhere. Homes in conservation areas, flats, and properties with Article 4 directions need planning permission for work that would otherwise be permitted, and side and multi-storey extensions have their own rules. Hillingdon has 31 designated conservation areas, so it is worth checking yours before you spend money on drawings.

We check your property's position before we quote, and we work with architects and planning consultants if you need a Lawful Development Certificate or a full planning application. Always confirm the position for your own home with Hillingdon Council.

Source note: Planning Portal (extensions, planning permission); Hillingdon Council (conservation areas).

Extensions need building regulations approval whether or not they need planning permission. If you share a wall with a neighbour, or dig near their foundations, the Party Wall etc. Act 1996 applies: notice must be served at least two months before work to a party wall, or one month before excavation near a neighbouring building, and your neighbour has 14 days to respond. Leave time for this in your plans.

We handle party-wall agreements, building regulations and structural engineer coordination as part of the job.

Source note: GOV.UK, Party Wall etc. Act 1996 explanatory booklet.

1. 1Free consultation and site visit. We listen, measure up and talk through your options.
2. 2Written fixed-price quote. Itemised, so you can compare it like for like.
3. 3Plans and approvals. We coordinate your architect, structural engineer and building control, and planning where needed.
4. 4The build. One dedicated project manager coordinates trades, materials and schedules, with weekly progress updates and quality control inspections.
5. 5Handover. Snagging walk-through and completion paperwork.

Also explore house extensions in Northwood, loft conversions in Uxbridge, and home renovations in West London.