The structural and architectural detail that decides whether your London basement feels like a habitable room or a cellar. Designed, waterproofed and installed by the team that dug the hole, warranted for 25 years.
Delta Registered Installers · 25-year structural & waterproofing warranty · Free site visit and design read.
A light well is the vertical opening: usually to garden or courtyard level: that brings daylight, ventilation and often direct access into a basement. It's the detail that transforms below-ground space into a room that reads and lives like the ground floor above. Get the structural, waterproofing and drainage detail right and the finished floor feels twice the space. Get it wrong and it's a permanent damp risk.
The design, structural excavation, waterproofing and finishing of light wells around new or existing basements: including retaining walls, drainage, glazing, sliding doors and safety detailing.
Homeowners with a new basement excavation, an existing basement that feels dark or airless, and any project where planning encourages a lower ground floor to open onto a garden or courtyard.
During new basement design, as part of a basement extension, or as a retrofit to bring daylight into an already-completed but under-lit basement.
Daylight and ventilation are the difference between a basement worth living in and a basement worth using for storage. Light wells cost money, but skipping them is the false economy that undoes the entire investment.
Every UHM project runs through the same structured stages. You'll always know what's happening next, who's doing it and when it completes.
Light-well position, size and access design worked through with your architect, weighed against daylight goals, garden layout and structural constraints.
Excavation of the light well against engineer-designed retaining walls, integrated with the basement's temporary works and party wall strategy.
Waterproofing detail at the light-well interface, drainage sized to design rainfall, connected to the basement's sump-and-pump system.
Sliding or bi-fold doors, safety glazing where required, surface grating, edge protection and railings to building control standard.
Structural and waterproofing sign-off, building control certificate and issue of 25-year warranties covering the completed detail.
Light wells come in several distinct forms, each with different structural, waterproofing and architectural implications. Here's the toolkit.
The most common form: a light well cut into the rear garden or courtyard, opening the basement to daylight and often to direct garden access via sliding or bi-fold doors. Retaining walls, waterproofing and drainage are integrated with the basement envelope.
Where garden light isn't possible, a courtyard cut into the property or an internal light well brought down through the ground floor slab can deliver daylight from above. Glazing at the top and structural detailing around the opening decide the success of the detail.
Historic London terraces often have coal-hole covers and vault glazing at pavement level. Modern equivalents, structural glass pavement lights and grated light wells, bring daylight to the front of the basement while managing highway safety and drainage.
Where a completed basement is under-lit, retrofit light wells can be introduced: subject to planning, structural condition and party wall consents. We survey feasibility first and give an honest read before quoting.
A properly designed light well makes a basement kitchen-diner or principal suite feel like a real ground floor, not a converted cellar.
Waterproofing detail at the light-well interface designed and installed to the same 25-year standard as the main envelope.
Drainage capacity calculated against design rainfall and connected to the main sump-and-pump system, no ponding, no backup.
The same directly-employed crew builds the light well and the surrounding basement. No handovers at the most-critical interface.
Edge protection, safety glazing and surface grating specified to meet building control expectations from the outset.
Bi-fold or sliding doors, natural stone edges, planted courtyards, the finish level that turns a functional detail into an architectural feature.
Cut corners on light-well detailing and you create the exact conditions the rest of the basement waterproofing is trying to prevent, water pooling against the structure, drainage backed up, safety hazards on the surface.
The junction between the light well, the basement wall and the ground is one of the most-loaded waterproofing details in the whole basement. Poor detailing here undoes the entire system.
A light well without properly sized drainage becomes a bath in a rainstorm. Standing water damages joinery, sills and finishes, and puts pressure on the waterproofing beneath.
Uncovered light wells or badly detailed grates are trip and fall hazards. Building control expects proper edge protection, glazing specification and safety detailing.
Adding a light well as an afterthought once the basement is dug.
Skipping the drainage sizing calculation.
Under-specifying the retaining wall design.
Using cheap grates that trap leaves and back the drainage up.
Ignoring the structural interface between existing wall and new opening.
Skipping the safety edge detail at surface level.
Straight answers we give on almost every free site visit, cost, timeline, guarantees and what's included.
Usually yes, particularly if they alter the external appearance of the property or extend beyond the existing footprint. We can advise informally at feasibility stage, working with your architect and planning consultant.
Priced per project. Cost depends on the size and depth of the well, the structural retaining design, the glazing and door specification, and the finish level. Site visits and quotes are free.
As part of a new basement excavation, light wells are built into the main programme. As a retrofit to a completed basement, they typically take six to twelve weeks depending on complexity.
In many cases yes, subject to planning permission, structural feasibility and party wall consents. We survey first and issue a written feasibility read before quoting.
The completed light well and its interface with the basement envelope are covered by the same 25-year structural warranty and 25-year waterproofing warranty as the main basement.
Drainage capacity is sized against design rainfall and connected to the basement's main sump-and-pump system. Twin pumps and battery back-up mean drainage keeps working through storms and power cuts.
Frequently yes, most substantial light wells need full planning permission. Small internal light wells or replacements of like-for-like features are sometimes permitted. Your architect and planning officer decide the case.
Building control expects proper edge protection: usually a combination of railings or planters, safety-rated glazing where applicable, and slip-resistant surface materials. All of this is designed in from the start on a UHM light well.
A director will visit, review your basement or design brief, and give you a written specification and quote, for free. If a light well won't work in your case, we'll say so.
