Treharris · Mid Glamorgan
Roof Lanterns in Treharris
We cover Treharris and the rest of Mid Glamorgan for roof lantern supply and fitting, from small skylights over landings to large lanterns for open-plan kitchens.
- CF46
- Guide from £1,095
Flat roof skylight for homes and businesses in Treharris
The price of a roof lantern or skylight depends on the size and shape, glass specification, frame colour, opening vents or electric operation, and whether the upstand already exists or needs building. Access to the roof and lifting large units add labour. See the guide prices for typical ranges.
Old polycarbonate or single glazed roof lanterns can be replaced with double glazed aluminium lanterns on the existing upstand, if the upstand is sound, level and the right size. Upstands that are rotten, uninsulated or out of level should be rebuilt first, which the survey identifies.
The Rooflight Association recommends laminated glass for the inner pane of glass rooflights, because laminated glass stays bonded together if it breaks instead of dropping fragments into the room below. Toughened inner panes are still used, but laminated is the safer choice over kitchens, stairs and seating areas.
Roof lanterns are made in rectangular, square and octagonal shapes, with hipped or gable ends. Frames are usually powder-coated aluminium, often grey or black outside and white inside. Manufacturing lead times depend on size and colour, and the expected timescale is confirmed in writing with the quote.
What a typical job includes
- Fixing, glazing and sealing onto the prepared upstand
- Made-to-measure aluminium roof lantern or framed skylight
- Removal and disposal of an old lantern or skylight
- Sealed double glazed units with laminated inner pane options

Treharris at a glance
- Postcodes covered
- CF46 and the surrounding area, including Nelson (Mid Glamorgan), Gelligaer and Mountain Ash
- Coast
- Treharris is well inland, around 23 km from the nearest coast, so salt exposure is not usually a factor.
- Daylight and sun
- In Treharris the midwinter sun reaches about 15° above the horizon at noon, with roughly 7.6 hours of daylight, rising to about 62° and 16.4 hours in midsummer. Overhead glazing receives far more light than a wall window of the same size, especially when the sun is high in summer. South-facing lanterns may need solar-control glass, while low winter sun and north-facing rooms benefit from clear, high light-transmission low-E glass.
- Access and setting
- Rural roofs collect more leaves, moss and bird debris, so lanterns need clear upstand drainage and regular checks. Exposed sites see higher wind loads and driving rain, and older outbuildings may need the roof structure strengthening before a lantern is added.
- Rules in Wales
- In Wales, Approved Document N covers safety glazing: safety glass is needed in and around doors and in low-level glazing where people could walk into it.
Guide prices in Treharris
| Typical job | Guide price inc VAT |
|---|---|
| Lantern 1500 × 1000 mm, fitted to a kerb | £1,395 – £1,795 |
| Lantern 2000 × 1000 mm | £1,695 – £2,095 |
| Lantern 3000 × 1500 mm | £2,795 – £3,695 |
| Flat glass rooflight 1000 × 1000 mm | £1,095 – £1,395 |
Get a guide price for your size
In Wales, replacing a whole window or glazed external door is building work and is notified either by an installer registered with a competent person scheme or through the local authority's building control. Replacing only the glass in an existing frame is treated as a repair.
What you can choose
Flat framed skylight
A low-profile framed rooflight on a flat roof upstand, fixed or opening, for bathrooms, landings and smaller rooms.
Solar-control glass
Neutral or blue-tinted coatings that reduce heat build-up under south or west-facing lanterns while keeping daylight levels high.
Frame colours
Powder-coated aluminium in grey, black, white or other RAL colours, often dual colour to suit the roof and the room.
Roof Lanterns in Treharris: questions
How long does it take to fit a roof lantern?
Fitting a roof lantern on a prepared upstand usually takes a day or less for a typical size, longer for large or complex shapes. The lantern is made to order first, and the lead time depends on its size, shape and colour. Building or rebuilding an upstand is separate roofing work that comes before fitting.
Does fitting a roof lantern need building regulations approval?
A new roof lantern or skylight generally needs building regulations approval, because the roof structure is cut and must be supported, and the unit must meet energy standards. Fire performance also matters near a boundary. Replacing a lantern on an existing sound upstand is simpler, and we explain which route applies at survey.
Why does my roof lantern get condensation?
Condensation forms when warm, moist air from cooking, bathing or drying clothes meets the colder glass and frames at high level. Older single glazed or non thermally broken lanterns suffer most. Thermally broken frames, warm-edge spacers, extractor fans and opening vents reduce it. Some condensation on very cold mornings is normal and clears as the room warms.
Should the inner glass in a roof lantern be laminated?
Laminated inner glass is the safer choice and is recommended by the Rooflight Association. If a laminated pane breaks, the interlayer holds the pieces together, so glass is far less likely to fall into the room below. This matters most over kitchens, dining tables, stairs and seating, and it is offered as a standard option.
Do you cover Treharris for roof lanterns?
Yes. We can quote for roof lanterns across Treharris and the surrounding Mid Glamorgan area, including postcode districts CF46, and nearby Nelson (Mid Glamorgan), Gelligaer and Mountain Ash. Start with your postcode on the quote form and a glazier will arrange a free survey before giving you a written quote.
Get a written quote in Treharris
Free survey for new glazing, clear guide prices and one point of contact for every glazing job.