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A roof lantern without a glazing bar has one continuous pane with no profiles in between. On the DagLichtDesign lean-to roof lantern, that is possible up to 5 metres wide. If the roof lantern is wider, one or more glazing bars are added, thermally broken just like the frame. So a glazing bar is not a sign of lower quality. It is a choice that depends on the size, the weight of the glass and how you want the lines in your ceiling to look.
A glazing bar is a profile that divides the glass into two or more panels. It runs from the low side to the high side and supports the edges of the glass panels. So a roof lantern with a glazing bar has several glass units side by side, each with its own edge.
The bar has to insulate just as well as the rest of the frame. That is why the bars are thermally broken: an insulating strip separates the inner and outer aluminium, so no cold line runs across your ceiling.
For the mono-pitch roof lantern, DagLichtDesign makes panels up to 5 metres wide without a glazing bar. Because a roof lantern is usually narrower than the extension itself, that is plenty for many extensions on a terraced house.
A single panel gives the most open look: from inside you only see the outline of the frame and an uninterrupted stretch of sky. The glass is heavy, though. Glass weighs about 2.5 kg per m² per millimetre of thickness. An insulating glass unit with a laminated inner pane quickly comes to 25 to 40 kg per m². A 5 by 1 metre panel then weighs around 125 to 200 kg.
On a lean-to wider than 5 metres, a bar is needed. But even below that size a bar can be a deliberate choice, for example in these situations:
A glazing bar is a line in your ceiling. Whether it bothers you depends on where it sits. Line it up with something that is already there: a wall, a mullion in the rear wall, the edge of a kitchen island or a beam. Then it reads as part of the design.
Divide the panels evenly. Two 3 metre panels look calmer than one of 5 and one of 1. And choose the colour with care: a white bar disappears against a white ceiling, while a black bar becomes a graphic line. More on this in choosing a frame colour for your roof lantern.
Other roof types work differently. A gable roof lantern goes up to 6 metres long and 4 metres wide per roof plane as standard, and is built modularly beyond that. A hipped roof lantern has up to 9 m² of glass in one piece. Larger versions use segmentation and concealed bars, which also contain the drainage.
More about long and large roof lanterns in a 4 metre roof lantern and under standard roof lantern sizes.
Fix the position of a glazing bar before the upstand and ceiling are built. The contractor can then align beams, spotlights and the line of the rear wall with it straight away.
On the DagLichtDesign lean-to roof lantern, up to 5 metres wide in a single panel. On a hipped roof it is a maximum of 9 m² of glass in one piece. Beyond that the glass is divided with bars or segments.
Not if the bar is thermally broken, as it is at DagLichtDesign. The edge of each glass unit does insulate slightly less than the centre of the glass, so more panels means a little more edge loss in theory. In practice the difference is small.
A panel of a few metres quickly weighs more than 100 kg. Two people cannot safely carry that up onto a roof. Plan for lifting equipment and follow the safety instructions for lifting and positioning in the installation manual.
A properly installed bar is watertight. The bars are part of the system and carry the water to the bottom rail. If a roof lantern does leak, the cause often lies in the junction with the roof or the upstand, see a leaking roof lantern.
Call us or send a photo of your roof. We are happy to help you choose the type, size and glazing.
Request a quote Get in touchA few questions, a photo or the dimensions, and we will prepare a tailored quote. Prefer to call: +31 342 223 190.
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