Part of our Flat Roof Skylight Installation service
Can You Install a Skylight on a Flat Roof in Cheltenham?
How flat-roof rooflights work, why the kerb and weatherproofing matter, and what to expect from the installation.
Yes, flat roofs are well suited to skylights. Fixed rooflights, opening rooflights and roof lanterns all sit happily on a flat roof, mounted on a raised kerb that lets water drain away cleanly. The work that makes it last is the kerb and the weatherproofing detail, which is exactly where a specialist installation earns its place.
Flat-roof extensions are one of the most popular places to add light from above, and the modern look of a frameless rooflight or a glazed lantern suits them well. Here is how it works and what to expect.
How a flat-roof skylight works
The kerb or upstand
A flat-roof skylight does not sit flat on the roof. It sits on a raised kerb, a built-up upstand, which lifts the glass above the water line and lets rain run off. The kerb is the heart of a watertight installation. If your builder has formed one accurately during the extension, that helps; if not, we can supply and fit an insulated upstand.
Weatherproofing and flashing
The roof covering is dressed up and over the kerb, and the rooflight is sealed onto it, so water is shed away from the opening. How this is detailed depends on the covering, felt, EPDM, GRP or single-ply, and getting it right is what keeps the roof dry for years.
Drainage and fall
Flat roofs are never truly flat; they have a slight fall so water drains. The skylight and kerb are detailed to work with that fall, not against it.
What you can fit on a flat roof
- Fixed flat-glass rooflights for a clean, modern, frameless look
- Opening and electric rooflights for ventilation and fresh air
- Roof lanterns for a raised, architectural feature over a larger space
- Walk-on rooflights where the roof doubles as a terrace or brings light to a room below
Our flat-roof skylight installation and roof lantern installation pages cover these in detail.
What to consider before fitting
The condition of the roof
A sound, well-laid flat roof is the ideal base. We check the covering and structure at survey so the rooflight goes onto something fit to take it.
Glazing for comfort
Flat-roof glazing faces straight up at the sky, so solar-control glass is often worth it to manage summer heat, paired with good insulation for winter. Our energy-efficient skylight page explains the choices.
Fixed or opening
A fixed pane is the most economical and gives the cleanest look. An opening or electric unit adds ventilation, useful in a kitchen or bathroom.
Why the detail matters
A flat-roof skylight lives and dies by its weatherproofing. Done well, it is a clean, bright, long-lasting feature. Done poorly, it is a source of leaks. This is why we focus on the kerb, the flashing and the seal, and why every installation carries our written guarantee on our workmanship.
To plan a flat-roof skylight properly, get a quote and we will survey the roof, recommend the right product and provide a fixed written price.
From quote to daylight, with no surprises
Fixed quote
A clear, fixed written price — online or by phone.
Survey
A specialist confirms the right glazing spec. Flexible times.
Install
Clean, weather-tight fitting that protects your property.
Guarantee
We tidy up and back the work with a written guarantee.
Frequently asked questions
Can you put a skylight on a flat roof?
Yes. Fixed rooflights, opening rooflights and roof lanterns all suit flat roofs, mounted on a raised kerb that lets water drain away. The kerb and weatherproofing detail are what make the installation last.
Do flat-roof skylights leak?
Not when fitted properly. A correctly formed kerb, good flashing and a sound seal keep a flat-roof skylight watertight for years. Leaks come from poor detailing, which is why specialist fitting matters.
Do I need a kerb for a flat-roof skylight?
Yes. A flat-roof skylight sits on a raised kerb to lift the glass above the water line. If your builder has formed one accurately it helps; if not, we can supply and fit an insulated upstand.
What type of skylight is best for a flat roof?
It depends on the room. Fixed flat-glass rooflights give a clean modern look, opening units add ventilation, and roof lanterns create a feature over larger spaces. We advise on the best fit at survey.
Helpful reading on this
Costs, comparisons and answers to the questions we’re asked most.
Other skylight services
Ready to bring the daylight in?
Tell us about your project and we’ll send a clear, fixed written quote — no pressure, no surprises.
- Fixed written price before any work starts
- No pressure, no obligation, no sales calls
- Flexible survey times that suit you
- A reply within one working day