The short answer
Choose frameless if you want the cleanest, flattest look from outside and the sharpest edge inside. Choose framed if you want a conventional, forgiving unit that is simpler to fit and straightforward to match to an existing kerb. Both can be made to meet current Part L, so the decision is mainly about appearance and the roof you have.
What the two terms mean
A frameless flat rooflight has glass that sits on the kerb with the framing hidden below the glass line, so from the garden or from above you see an unbroken pane. A framed rooflight has a visible frame around the glass, usually aluminium or PVC, and the glazing sits within it. People searching for a frameless flat rooflight are usually after the first look. The framed rooflight is the more traditional build and is still the right choice on many roofs.
How each one looks from outside and inside
From outside, a frameless unit looks like a sheet of glass laid on the roof. There is no frame to catch the light and the profile is low. A framed unit shows its edge, which can be slim and dark or broader and more visible, depending on the system.
From inside, the difference lies in the edge of the opening. A frameless rooflight lets the glass meet a crisp reveal, and where the roof depth allows we splay and plaster that reveal so the line is clean. A framed one has a frame member on show at the edge, so the lining is detailed to meet it neatly. Either way, we plaster and make good the reveal, so the finished room looks designed.
Fitting and the kerb
Frameless units are usually fixed to a purpose-made kerb, with the glass bonded or fixed so no frame appears. The kerb and upstand must be accurate, because a hidden frame leaves less room to disguise a slightly out-of-true opening. A framed unit tolerates a little more, and many framed rooflights can be matched to an existing kerb of the right size. The junction itself is covered in our kerb and upstand guide, and for a swap on an existing kerb see replacing a rooflight on the same kerb.
A side-by-side comparison
| Question | Frameless | Framed |
|---|---|---|
| Look from outside | Flat glass, no visible frame | Glass with a visible frame |
| Look from inside | Crisp, minimal edge | Frame edge shows at the reveal |
| Kerb | Needs an accurate, purpose-made kerb | More tolerant, often suits an existing kerb |
| Opening option | Available on some systems | Widely available |
Cleaning, maintenance and long-term wear
Glass is glass, so both styles clean the same way: a soft cloth or brush and clean water, from the roof side where it is safe to reach and from the room side where the unit opens. The difference is at the edges. A frameless unit has fewer places for dirt to settle against a raised frame, so the surface tends to look cleaner for longer. A framed unit has frame joints and a gasket line that benefit from a look when you clear the roof.
The bonded or sealed edge of a frameless unit is the part that matters over the years, which is another reason to have it fitted by someone who builds the kerb to suit. A framed unit with a good gasket is forgiving, and a failed seal can often be dealt with by changing the glazed unit alone while the frame stays in place.
Opening, ventilation and shading
If you want the rooflight to open for air, the choice of style narrows. Framed systems offer opening versions across a wide range of sizes, with manual or electric operation and rain sensors. Some frameless systems also open, usually by lifting the glass on concealed hinges, but the range is smaller and the cost to you is set out in your fixed quote, not guessed in advance. If the room is south-facing and gets hot, glass that controls solar gain, or an internal blind, matters more than the frame style.
Energy and the rules
Frame type does not decide compliance. A whole replacement is building work, and either style has to reach 2.2 W/m²K as a flat-roof rooflight. We confirm the figure with the maker for the exact size we quote, and the Building Control paperwork is ours to sort out. The regulations themselves are explained in this short answer on Building Regs.
Security, strength and glass choices
The glass is laminated or toughened according to the unit, and the maker states what the glazing is rated for. Neither style is automatically stronger. A frameless pane relies on its bond to the kerb, and a framed one relies on the frame and its fixings. If anyone will need to walk across the roof, that calls for walk-on glass specified to the manufacturer's stated load rating, not a standard rooflight of either style.
Glass options are open on both. Clear glass gives the most light, tinted or solar control glass cuts glare and heat, and self-cleaning coatings help between washes. These choices are independent of the frame decision, so settle them separately at the survey.
Which one suits you
If you want the glass to read as part of the roof and you are happy with a purpose-built kerb, frameless is the answer. If you want a proven, simple fit, or you are matching an existing opening, framed makes sense. We talk through both at the free survey with your roof in front of us, give you a fixed written quote for the one you pick, and finish the room inside with a 10-year workmanship guarantee on our installation.
