Basement contractors in London. We design, engineer and build basements under one contract. Basement cost in London, the 2026 figures.
Most people picture a basement as a dark room. The good ones feel like the ground floor.
The difference is rarely the finishes. It is how light reaches the room, and how early that was decided.
Daylight is not a detail to add later. It shapes the structure, the drainage and the planning case.
What makes a basement feel like a normal floor
Light is only one part of it. Room proportions, ventilation, acoustics and the stair connection matter just as much.
A generous stair can carry light down from above. A cramped one makes the whole floor feel cut off.
So set a daylight and comfort brief for each room. Decide which rooms truly need daylight and which do not.
Lightwells are structure, not windows
A lightwell is a hole in the ground beside the house. It has to be held up, drained and kept dry.
That means it is planned with the engineer from the start. Lightwells should be designed alongside structure, privacy and water management.
Rain falls straight into a lightwell. Where it goes next is part of the waterproofing and drainage design.
Privacy matters too. A lightwell at the front can look straight into a bedroom from the pavement.
Rooflights and glass roofs need more than a supplier
Where the basement runs under the garden, a rooflight can drop light straight in. A glass roof over a rear room can do the same.
Glazing needs coordination for structure, heat gain, shading and maintenance. The comfort of the room below matters as much as the view up.
More glass does not always make a better room. Review orientation and summer comfort as well as appearance.
Ask how the glass will be cleaned. Ask how it drains, and who can reach it safely.
Do not let the new floor darken the old one
Extending at the back can make the middle of the house darker. The same is true below ground.
Test the existing rooms as well as the new space. Use openings and circulation to share useful light across the whole floor.
A glazed rear wall can serve the kitchen and the stair at once. A borrowed light panel can reach a hallway.
Planning, neighbours and rights to light
Lightwells and rooflights change how a house looks from outside. They are part of the planning case, not an afterthought.
Check current local policy for the actual address. Never assume a size or depth. Trees, planting and neighbours all need consideration.
A private right to light is a separate matter from planning. A planning approval does not settle every private property issue.
Ask early whether specialist surveying or legal advice is needed.
The order that works
Daylight brief first. Structure, drainage and planning second. Finishes last.
Done that way, daylight is priced in from day one. Then read what really drives the cost of a London basement.
A basement planned around its light is a room people actually use.
Planning a basement and want daylight designed in from the start?Fill out the contact form or call 020 7731 6841 and let’s get you booked in for a free call with Nick.
This is the work we do. Basement contractors in London, or ask for a cost estimate.
Published 9 October 2026. Written by the NU Projects studio, edited since for house style and accuracy.