Replace a rooflight dome with a roof lantern

Why people replace a rooflight dome

A plastic rooflight dome lasts for years, but eventually turns dull or yellow. The view of the sky disappears, the insulation falls short of modern glass and an old dome can start to leak. At that point the question is whether to fit a new dome or switch to glass. The differences are explained under roof lantern or rooflight dome.

A glass roof lantern gives clear light and a view of the sky. HR++ double glazing is standard, with a U-value of about 1.1 W/m²K. Sound reduction is also better than with a thin plastic dome, which you notice when it rains.

• Clear glass instead of dull or yellowed plastic
• Better insulation with HR++ or triple glazing
• Less noise from rain and hail
• Clean aluminium frame in any RAL colour

Replacing a flat roof dome: how it works

First, the existing dome and upstand are removed. Then your builder checks whether the opening is the right size. Many domes sit in a small opening. If you want more light, the opening is enlarged. That is usually possible, as long as the structure allows it. A builder or structural engineer assesses the load-bearing capacity.

Next comes a new or adapted upstand, and the builder fits the new roof lantern, usually a mono-pitch roof lantern. The roof lantern connects watertight to EPDM or bitumen. Everything involved with an existing roof is covered under a roof lantern in an existing flat roof.

Replacing a roof lantern: old ones too

It is not only domes that get replaced. An old roof lantern made of polycarbonate or with single glazing can also come out. The principle is the same: remove the old structure, check the upstand, fit a new made-to-measure roof lantern. Why glass often beats plastic sheets is explained under glass or polycarbonate.

If your current roof lantern leaks, first find out where the water is coming from. Sometimes the problem is in the connection rather than the roof lantern itself. The article leaking roof lantern will help you on your way.

Cost and permission

What replacement costs depends on the size, the glass and the work on the opening. See how much a mono-pitch roof lantern costs for more. The roof lantern itself usually does not need separate planning permission. If in doubt, always check with your municipality, especially if the roof is visible from the street.

Frequently asked questions