Planning a Home Extension? Don’t Overlook These Rooflight Rules & Design Tips
So, you're planning a home extension—maybe a rear kitchen, a side return, or even a loft conversion. You've picked out your bifold doors, chosen the flooring, and are deep into Pinterest inspiration...
But wait—have you thought about the rooflights yet?
Because if you’re dreaming of a bright, airy space (and who isn’t?), rooflights can make or break your extension. And yes—there are rules you need to know before you go cutting holes in your roof.
Let’s break it all down—the planning rules, building regulations, and design tips that’ll save you stress and help you get the most out of your rooflight setup.
🚫 First, do you need planning permission for rooflights?
Usually, no.
In most cases, rooflights fall under permitted development rights, which means you don’t need full planning permission as long as you meet the rules.
Here’s what the UK guidelines say (as of 2025):
✅ Your rooflight must:
Not project more than 150mm above the roof surface
Sit below the highest part of the roof (no poking above the ridge)
Be obscure-glazed and non-opening if it’s on the side roof slope and less than 1.7m above the floor
Sounds simple, right? It usually is—but there are exceptions.
⚠️ You WILL need permission if:
Your property is listed
You’re in a conservation area, AONB, or national park
You’re building a two-storey extension
You want an oversized or raised rooflight (like a lantern)
When in doubt? Call your local planning office or ask your architect.
🧱 Don’t forget about building regulations
Even if your rooflight doesn’t need planning permission, it must meet Building Regulations.
Why? Because you’re making a structural change to your roof. And the glazing itself has to meet thermal and safety standards.
Here’s what the regs care about:
U-value (thermal efficiency) – The rooflight needs to keep heat in during winter. Aim for a U-value of 1.2 W/m²K or better.
Structure – Your roof needs extra framing (called trimmers) to support the glass.
Ventilation – If it’s the only window in the room, you may need a model that opens.
Safety glass – Think toughened or laminated. Especially important in overhead glazing.
Pro tip: Reputable brands like Saris-Extensions design their frameless skylights to fully comply with UK building regulations—making them a smart starting point for your project.
🖼 Design tips: Make your rooflight work for the space
It’s not just about compliance—it's about getting the design right. Here’s how:
1. Think about the view from below
Do you want to see just the sky? Then go frameless.
Want an industrial vibe? Try a roof lantern with slim aluminium bars.
If it’s above a table or island, symmetry matters—measure carefully!
2. Match the rooflight to the roof type
Flat roof? Go for a fixed rooflight or lantern on a kerb (100–150mm high).
Pitched roof? You’ll want a roof window (like a VELUX or ROTO) that sits flush and follows the roofline.
3. Size matters—but so does placement
A small rooflight in the wrong spot won’t help.
A well-placed one can flood your kitchen, hallway, or loft with natural light—even on gloomy days.
Tip: Don’t put it too close to the wall—you’ll waste light potential. Let it land in the middle of the room if you can.
4. Watch for overheating
Modern glass is clever. You can choose solar control coatings that reflect summer heat and low-emissivity layers that hold warmth in winter.
If your rooflight faces south or west, definitely consider:
Solar control glazing
Integral blinds
Or even external shading
5. Make cleaning easy
If you can’t reach it, it’s probably worth getting:
A non-opening unit (less to clean and maintain)
Self-cleaning glass (it’s not a gimmick—rain actually helps wash it!)
Or a model with remote control blinds or openers
🛠 Common mistakes to avoid
Here’s what trips up homeowners all the time:
🚫 Choosing a rooflight too small for the space
🚫 Forgetting ventilation requirements
🚫 Skipping planning checks in conservation areas
🚫 Picking cheap, single-glazed models that cause condensation
🚫 Assuming any builder can install one—roof glazing is specialist work!
🏠 Final thoughts: Rooflights are small details that make a huge difference
When you’re planning your extension, it’s easy to focus on the big stuff: layouts, doors, finishes.
But rooflights? They’re the unsung heroes of modern home design.
They make dark kitchens bright. They open up narrow rooms. And they connect your home to the sky.
Just make sure you:
Follow the rules
Meet the building standards
Choose the right type for your roof
Design with light, not just glass
Because when you get it right, a rooflight doesn’t just light the room—it transforms it.
Need help picking the right rooflight for your extension?
Ask your builder about kerb height, U-values, or whether you’ll need an opening version. Or contact us—we’ll help you choose based on your space and your style.