Basement Conversions · London
When you have run out of room above ground, the only way is down. We design and build basement conversions across London - from straightforward cellar dig-outs to full excavations with lightwells, waterproofing and everything in between.
Discuss Your Basement Project
What We Do
Basement conversions are some of the most rewarding projects we work on. You are creating an entirely new floor of living space without extending the footprint of your home - and in London, where every square metre counts, that is a serious advantage.
Some of our clients have an existing cellar that just needs tanking, lowering and fitting out. Others want a completely new basement excavated beneath their house, sometimes with lightwells to the front or rear garden. We handle both, along with all the structural engineering, waterproofing and building regulations work that goes with it.
Every basement project is different, which is why we do not offer fixed packages. We look at your property, talk through what you want to use the space for, and design something that actually works - structurally, practically and aesthetically.
Our Approach
Basement projects involve more moving parts than most residential work. There is the architect, the structural engineer, the party wall surveyor, the waterproofing specialist, the building control officer - and the builder tying it all together. If those people are not properly coordinated, things go wrong quickly.
At Rosace, the architecture and construction sit under one roof. We appoint the structural engineer, we manage the party wall process, and we build the basement ourselves. You deal with one team and one contract. It is genuinely simpler.
We also spend time getting the design right before we break ground. A basement should not feel like a basement. Good ceiling heights, carefully placed lightwells, and warm, considered finishes make the difference between a room people avoid and one they actually prefer.
We work across Greater London, with particular experience in Kensington, Chelsea, Hampstead, Fulham, Wimbledon and Kingston - areas where basements are common and property values justify the investment.
How It Works
01
Survey
We visit the property, assess the existing structure and ground conditions, and give you a clear picture of what is feasible - including likely costs and programme.
02
Design
We design the basement layout, lightwells and any connections to the ground floor. The structural engineer works alongside us to ensure everything is buildable and safe.
03
Planning
We handle the planning application where required, plus party wall notices to adjoining owners. We manage all council correspondence and any conditions that come back.
04
Build
Our construction team delivers the excavation, underpinning, waterproofing and fit-out. One contract, one project manager, no gaps between design intent and what gets built.
Common Questions
