Modern Rear Extension in Chiswick, London – Full Project from Start to Finish

Modern Rear Extension – Chiswick, London

This job in Chiswick, West London was one of those projects that really show what a good extension can do to a home. The old rear structure had been there for years — small, cold, and not very practical. The clients wanted to replace it with something more open and bright, so we started fresh, taking the old one down completely and rebuilding from the ground up.

Demolition and Groundwork

We began with the demolition and groundwork. The foundations needed to be deeper and stronger for the new design, so we dug everything out and poured new concrete footings with reinforcement. At the same time, we took care of all the drainage work — both inside and outside — including a new rainwater system to make sure everything runs properly for years ahead.

Structural Work

Once the ground was ready, we moved to the main structure. We built new brick walls and installed steel beams to support the roof. The design included a flat roof with two skylights, which completely changed how the space feels — it’s now filled with daylight even on a cloudy London day.

Insulation and Flooring

We took our time with the insulation — it’s one of those things you don’t really see, but it makes a big difference once the place is finished. We added proper layers under the floor and in the walls so the house keeps warm in winter and cool in summer. The base had to be solid, so we poured a new concrete slab, laid the membranes, and finished it all with a clean screed. It was a slow process, but worth it — everything lined up perfectly in the end.

Interior Finishing

Once the main build was done, we moved inside for the finishing work. We put up new plasterboards, skimmed the walls, and laid the flooring. That’s the part where you really start to see the house come together — when the bare shell turns into a proper living space. The new room feels open, tidy, and bright — exactly what the client had in mind from the start.

Exterior Details

On the outside, we installed new fascia boards and guttering to handle rainwater and finish the roof neatly. Every corner and joint was checked twice to make sure the detailing matched the clean, modern look of the new extension.

The Result

In the end, this extension gave the clients exactly what they were hoping for — a larger, warmer, and brighter space that blends beautifully with the original building. It’s modern but still feels like part of the home, not just something added on. From the first day on site to the final touch-ups, every part of this project was managed and built by our team — carefully, professionally, and with pride.

Frequently Asked Questions

Do you build house extensions in Chiswick and West London?

Yes. Chiswick, Acton, Ealing, Hammersmith and the surrounding areas are regular working ground for us. This project was a full rear extension in Chiswick, taken from demolition through to final finishes by our own team.

Why did this extension need new foundations?

The new structure placed different loads on the ground than the old rear building had, so the footings needed to be deeper and stronger. We excavated and poured new reinforced concrete footings before anything was built on top. On older London houses this is common — existing foundations are often shallower than current requirements.

What kind of roof was used on this extension?

A flat roof with two skylights. Flat roofs suit single-storey rear extensions where height is restricted, and the skylights bring daylight into the middle of the plan — something a rear window on its own cannot do.

Was the drainage altered during the build?

Yes. Drainage was renewed inside and outside, including a new rainwater system. Rear extensions frequently sit over or close to existing drains, so this gets dealt with at groundwork stage rather than discovered later.

How much does a rear extension like this cost in London?

Build costs typically run from around £45,000 for a small rear extension up to £110,000 for a larger one, before kitchen units, appliances and VAT. Groundwork, steel spans and glazing move the figure most.

How long does a rear extension take to build?

Ten to sixteen weeks on site for a typical rear extension, plus design and approvals beforehand. Groundwork and foundations take the first two to three weeks, and that stage looks slow because it is.