Dorchester · Dorset
Roof Lanterns in Dorchester
Our glaziers fit roof lanterns across Dorchester, glazing and sealing each unit onto its upstand and explaining any building regulations approval the work needs.
- DT1
- Guide from £1,095
Roof lantern replacement for homes and businesses in Dorchester
In England, a rooflight on a house is usually permitted development if it projects no more than 150mm beyond the roof plane and is no higher than the highest part of the roof. Raised lanterns often stand taller than that, so check with the council before ordering.
Warm, moist air rises and collects in a roof lantern, so condensation can form on cold winter mornings, especially over kitchens and bathrooms. Thermally broken frames, warm-edge spacers and good room ventilation reduce it, and opening vents in the lantern can release warm air in summer.
In England, Approved Document L sets a limiting U-value of 2.2 W/m²K for rooflights, calculated in the horizontal position, for both new and existing homes. A kerb or upstand built on site should achieve 0.35 W/m²K or better. Ask for the lantern's declared horizontal U-value, not a vertical figure.
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.
What you get
- Survey of the roof, opening, upstand and drainage
- Removal and disposal of an old lantern or skylight
- Sealed double glazed units with laminated inner pane options
- Written guarantee terms and manufacturer documentation
About Dorchester for this job
- Postcodes covered
- DT1 and the surrounding area, including Weymouth, Bridport and Yeovil
- Coast
- Dorchester sits roughly 8 km from the nearest coastline, close enough that exposure on open or high ground is worth considering. Coastal lanterns face salt deposits on the glass and frames and strong uplift from wind on exposed roofs. Marine-grade coatings, stainless fixings and secure fixing to a well-built upstand matter, and salt film may need rinsing more often than self-cleaning glass manages alone.
- Daylight and sun
- In Dorchester the midwinter sun reaches about 16° above the horizon at noon, with roughly 7.7 hours of daylight, rising to about 63° and 16.3 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 England
- Approved Document K requires safety glass in critical locations in England: glazing in doors and in side panels within 300 mm of a door, up to 1500 mm above floor level, and any glazing in walls or partitions up to 800 mm above floor level.
Guide prices in Dorchester
| 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
Approved Document L sets the minimum energy performance for replacement windows and doors in existing homes in England: a U-value of 1.4 W/m²K, or Window Energy Rating band B for windows; doors can instead meet a Door Set Energy Rating (band B, or band C for doors more than 60% glazed); rooflights need 2.2 W/m²K.
What you can choose
Rectangular hipped lantern
A long ridge with hipped ends, suiting most rectangular extensions and kitchens, sized to the opening and the room below.
Opening vents
Manual or electric vents in the lantern or skylight, with optional rain sensors that close them automatically in wet weather.
Solar-control glass
Neutral or blue-tinted coatings that reduce heat build-up under south or west-facing lanterns while keeping daylight levels high.
Roof Lanterns in Dorchester: questions
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.
Will a roof lantern make my room too hot?
A roof lantern can add heat on sunny days, especially facing south or west, because overhead glass receives sun for much of the day. Solar-control glass, opening vents and blinds help keep the room comfortable. The glass is chosen at survey based on the lantern's size and orientation and how the room is used.
Do I need planning permission for a roof lantern?
Sometimes. In England, rooflights on a house are usually permitted development if they project no more than 150mm above the roof plane and are no higher than the highest part of the roof. Raised lanterns often exceed that, and flats, listed buildings and conservation areas have extra controls, so check with your council first.
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.
Do you cover Dorchester for roof lanterns?
Yes. We can quote for roof lanterns across Dorchester and the surrounding Dorset area, including postcode districts DT1, and nearby Weymouth, Bridport and Yeovil. 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 Dorchester
Free survey for new glazing, clear guide prices and one point of contact for every glazing job.