Internal windows and borrowed light

An internal window is a fixed glazed panel set into an internal wall to borrow daylight from a bright room for a dark one — an inner hallway, a landing, a windowless bathroom or a box room. A glazed fanlight over a door does the same job.

£450–£800per m² plus VAT, supplied and fitted (guide)

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Internal windows and borrowed light — illustrative interior

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Toughened and laminated safety glass
Surveys across the UK
Fixed-price written quotes

What are internal windows and borrowed light?

Borrowed-light panels can be framed in slim steel-look profiles to match a screen or door, or set frameless into the plaster. Obscure glass keeps privacy where the window looks into a bathroom or bedroom.

Options and specification

Fixed internal windows, transom lights and door fanlights
Steel-look framed or frameless in a plaster reveal
Clear, reeded, satin or laminated acoustic glass
Openings formed in stud walls; masonry walls assessed first

Guide price: £450–£800 per m² plus VAT, fitted
Minimum job: About £450 plus VAT
Lead time: Typically 3–5 weeks from survey
Best for: Victorian and Edwardian inner halls, landings, loft conversions and windowless en-suites

Where they work best

We most often fit internal windows and borrowed light in Victorian and Edwardian inner halls, landings, loft conversions and windowless en-suites. At the survey we'll look at the light, the way the space is used and the structure around the opening, and suggest a layout that works for it.

Building Regulations and safety

Glass within 800mm of the floor must be safety glass. Cutting into a masonry wall may need a lintel and, if the wall is load-bearing, structural calculations; stud walls are usually straightforward.

How the job runs

We survey and measure, send a drawing and a fixed written price, then make your glazing to order — lead time is typically 3–5 weeks from survey. On the day, floors are protected, the frame or track is fixed, the glass is set and sealed, and the space is cleaned before handover.

Questions about internal windows and borrowed light

Does an internal window need Building Regulations approval?

Usually not on its own, but forming an opening in a load-bearing wall needs a lintel and Building Control sign-off. Glass near the floor must be safety glass.

Will people be able to see through it?

Choose reeded, satin or acid-etched glass for privacy — it still passes most of the light.

Can you match my existing doors?

Yes. Frames can be finished in any RAL colour, with glazing bars set to line through with an adjacent door or screen.