Kitchen extension with a long roof lantern over the island and glazed doors to the garden

Roof Lanterns in Derby

A lantern sized to the spot it has to light.

Tell us where you eat, cook or sit. We size and place the lantern so the daylight falls there.

Book a free survey

Free survey
Fixed written quote
10-year workmanship guarantee

Three places a lantern lights well

Dining room with stone walls and a roof lantern centred over a long wooden table — Over the dining table, where the family stays on after the plates are cleared.

Green-walled dining room with a roof lantern above the table and French doors beyond — Over a green-walled dining table, with French doors beyond.

Sitting room with a sofa and plants under a pyramid roof lantern — Over the sofa end of a long extension that the back window never reaches.

Ten years on our workmanship. In writing.

Surveyed before we price
A fixed written quote that does not change on the day
Building Control notification handled

How the guarantee works

Close view of a grey aluminium roof lantern on a flat roof beside a brick house

The full guide

Roof lanterns, from the table up

A roof lantern is a raised glazed roof that sits on a flat roof and sends daylight down into the room. It looks simple from the garden. Underneath, the spot, the opening, the upstand, the glass and the rules all have to agree. This guide takes them in that order, starting where you sit.

Over the table
Shape and glass
Kerb and vent
Opening and well
Lantern or window
Rules and sign-off

Callout 1

Start where you sit, then look up

What goes on the survey sheet

Where you sit or work: marked on the floor plan
Ceiling height: measured inside the room
Joist direction and size: checked from inside or on the roof
Which way the roof faces: noted for the glass choice
Falls and outlets: traced across the flat roof
Steels and walls: located before the opening is drawn

When people search for roof lanterns Derby wide, they usually start with the product. A raised glazed roof, a ridge, slim bars, a lot of sky. It is a handsome thing, and it is easy to fall for the look. But a roof lantern is a skylight and a rooflight at once, and like any rooflight it only earns its place if the daylight it gathers lands somewhere useful. So we start with the person, not the roof.

At the free survey we ask a plain question. Where do you stand, sit or work in this room? The answer is a particular place. The end of the dining table where the family settles. The worktop where the vegetables get chopped. The reading chair in the corner of an extension that the garden doors never quite reach. We mark that place on the floor plan, and everything else follows from it. Roof lantern installation is a job of lining up a hole in the roof with a spot on the floor.

Why the middle of the ceiling is a poor default

A lantern centred on the ceiling because the ceiling is there will light the middle of the floor. That might be an empty strip between the table and the units. If the table sits under the bifold doors and the island sits against the back wall, a centred lantern throws its light between the two and flatters neither. Moving the opening a few hundred millimetres towards the table can change how the whole room feels, and it costs nothing extra at the planning stage, because it is only a line on a drawing.

The roof then gets its say. Joists run one way and not the other. A steel beam may sit exactly where you would like the opening. The flat roof has to fall to its outlet, so the ground around the lantern cannot be level. We look at all of this at the survey, from inside the room and, where it is safe to do so, from the roof, and we tell you which of the possible positions the structure allows.

One room, two places that matter

Open-plan extensions can have two spots. A long, narrow lantern can span both, or two smaller lanterns can each sit over one. The choice depends on the joist direction and on how the room is used through the day. A household that eats at the table but cooks for an hour at the island may want the lantern weighted towards the table, with the island lit by the spill from the edge of the light well. A household that works from the kitchen all day may want the opposite.

We draw the options on a simple plan so you can see where the daylight will fall before anything is ordered. Sizing comes next, and it has its own page. For the arithmetic of floor area, ceiling height and opening, read sizing a roof lantern for the room below. It is worth a look before the survey if you like to arrive with a rough idea.

What the survey records

No price is given until the survey is done, and the visit costs nothing. Alongside the spot, we record the things that decide whether the spot can be served from the roof. The sheet below shows what goes on it. None of it is exotic, but all of it changes the answer, and a lantern ordered without it can arrive a few centimetres wrong in a way no one can fix on site.

Roof lanterns suit extensions, orangeries, flat-roofed garages turned into rooms, and some flat-roofed Victorian and Edwardian rear outriggers where a kitchen has been extended over the old yard. They are less suited to a steep pitched roof, where a roof window or a run of VELUX windows does the same job with less fuss. We say so when that is the honest answer, because sending a customer away with the right product is better than fitting the wrong one.

Choose the spot first. The ceiling only decides whether the opening can sit above it.

Callout 2

Shape, frame and glass

Roof lanterns are made to measure, so the size is not limited to a catalogue list. The frame is usually aluminium with slim glazing bars, or uPVC on some ranges, and the shape can be a rectangle with hipped ends, a square pyramid or a long plateau with a short ridge. Each manufacturer has its own bar profiles and colours, and we fit lanterns from more than one range, chosen for the roof and the look you want. Bespoke is the normal way to buy a lantern, not an upgrade.

Shape is mostly about proportion. A long hipped rectangle echoes a long kitchen extension and carries the eye down the room. A pyramid suits a square room, because its four faces meet in a point above the middle. A plateau sits lower, with a flatter top, and works where the roof is shallow or the house is modern and the clean line matters more than height. The table shows the common choices side by side.

Proportion from the garden

A lantern that is too small for the room looks like a hatch. One that is too large can dominate the roofline and, on a south-facing extension, warm the room more than you want. From outside, it should sit comfortably within the flat roof with a clear margin of roof around it. That margin leaves space for the drainage to run past and for the upstand to be weathered properly. We check the view from the garden and from any upstairs windows that look down on it, because a lantern is seen from above as often as from below.

The glass build-up

The glass in a lantern does more work than the glass in a wall window, because it faces the sky for most of the day. In summer it takes the sun almost overhead. In winter it is the coldest surface in the room. Most lanterns use double glazed sealed units with a low emissivity coating, which reflects heat back into the room. Triple glazing fits a third pane, which holds more heat in, at the cost of weight and a slightly lower light level. Solar control glass carries a coating that cuts heat from direct sun while letting daylight through. Self-cleaning coatings use daylight and rain to loosen dirt on the outer pane, useful where nobody wants to climb up and clean the roof. Tints soften glare and change how the sky looks from inside.

Our page on roof lantern glazing, solar control, self-cleaning and tints compares these coatings in more detail, with the trade-off each one carries. If you are trying to decide between them, the question to ask is which way the roof faces and what the room is used for at two in the afternoon in July.

U-values in plain terms

A U-value measures how much heat passes through a material, and lower is better. Existing homes are covered by Table 4.2 in Approved Document L (Part L 2021). Any new or replacement rooflight, a lantern included, must reach 2.2 W/m²K. A roof window is judged as a window instead and is held to a tighter number than a lantern (see the 1.4 W/m²K window limit, or the WER band B route). Modern lantern glazing is designed to meet its limit, and we give you the figure for the unit we quote. Our energy efficient rooflights page covers the wider picture, including what the numbers mean for winter heating.

Plastic and glass are both used in lanterns. Polycarbonate and GRP panels turn up on lower-specification roofs and on some commercial buildings, while a residential extension with an eye on thermal performance and appearance is normally glazed with sealed glass units. We talk through the options and leave the choice to you.

Shapes and frames compared

How the common lantern shapes differ on a flat roof.
Shape	Looks like	Suits
Hipped rectangle	Long ridge, sloped ends	Long kitchen extensions
Pyramid	Four faces, one point	Square rooms
Plateau	Low, flatter top	Shallow or modern roofs
Multi-bay	Two lanterns, one frame	Two spots, one room

Callout 3

The kerb that keeps water out

A lantern never sits straight on the roof covering. It sits on an upstand, a raised kerb built around the opening, usually in timber and insulated, so the roof covering can turn up its sides and the lantern frame can stand above the level that rainwater runs at. On a flat roof, water moves slowly and can pond, so the height of that kerb and the way the covering is dressed up it are what keep the room watertight. Flashings, the thin metal or membrane strips that close the joint between the kerb and the lantern, are the last line of defence and need the same care as the kerb itself.

The upstand is also where the lantern is fixed down. Its top must be level and true, because a lantern frame set on a twisted kerb will not seal along every edge. Where we build the upstand as part of the job, the lantern arrives to a kerb we have checked is level and square. Where a builder has formed the kerb for a new extension, we measure it before the lantern is ordered, because a kerb that is a few millimetres out of square means a frame that is made to fit it.

Flat roof coverings and the lantern

Derby extensions carry a mix of flat roof coverings. There is torch-on felt, single-ply membranes such as EPDM, and GRP fibreglass. Each is weathered up the upstand in its own way, and the joints need something sound to bond to. Where the existing roof is old, brittle, discoloured or cracked, the area around a new lantern may need recovering so the new work is not sitting on a tired surface. That shows up at the survey and goes into the fixed written quote, so there are no surprises when the covering is lifted.

The same applies to the lantern frame. Aluminium needs little more than a clean now and then. A uPVC frame can discolour over the years and should be specified in a colour that will wear well. Either way, the frame and the covering are two systems that meet at one joint, and the survey looks at both.

Working at height

Lifting a lantern onto a roof is a job for the right equipment. Large frames and heavy glass units may need a crane or a lifting plan, and the working area needs edge protection while the lantern is set down. Fall protection and safe access are part of the plan from the first visit, not an afterthought on the day. If scaffold is needed, it is allowed for in the quote, because a fixed price has to include it.

Ventilation from the lantern

A fixed lantern lights the room but does nothing for the air. Some rooms need light and air together, so lanterns can be made with an opening vent at one side or along the ridge, operated by hand or by an electric actuator. Warm air rises and leaves through the vent, and fresh air is drawn in at a lower window. An opening vent is among the most effective ways to keep a south-facing extension comfortable, and we plan its position at the survey alongside the rest of the frame. Controls, rain sensors and wiring are covered under electric opening rooflights.

Water moves slowly on a flat roof. The kerb is what keeps it from finding a way in.

Callout 4

Cutting the opening and lining the well

The opening is the hole in the roof structure that the lantern sits over. Its size sets the size of the lantern, so it is worth getting right. In a new extension, the builder can frame the opening as the roof goes on, which is simpler and usually tidier. In an existing flat roof, forming it means cutting joists and fitting trimmers, which are timbers that carry the load of the cut joists across to the ones left whole. The joists to be cut are propped from inside first, and the trimmers are sized to the span.

That is structural work. A roof lantern is heavy for its size, and the load it puts on the kerb, the trimmers and the walls beneath has to be accounted for. Where an existing roof is in doubt, or a steel is needed, the structural checks happen before the lantern is ordered. In a loft conversion on a pitched roof, the picture is different, and roof windows are the usual answer. Our roof windows page covers that.

The light well

Inside, the opening leaves a shaft between the ceiling and the base of the lantern, called the light well. Its depth is the thickness of the roof build-up, so joists, insulation and the deck all count. The sides of the well can be square or splayed. A splayed well, angled outwards as it drops, spreads the light wider across the room and makes the lantern feel larger from below. A square well keeps the light more concentrated on the spot underneath. The choice follows from the spot you picked in the first place.

What pushes a lantern quote up or down

Size and shapeLarger, more complex frames need more glass and more bars.
New or existing roofCutting into a finished roof adds propping, trimming and making good.
Glass specificationTriple glazing, solar control and self-cleaning each add to the unit.
Roof coveringA tired covering may need recovering around the lantern.
Lifting and accessHeavy glass may need a crane, scaffold or a lifting plan.
Opening ventHand or electric opening adds hardware and sometimes wiring.

The well is lined with insulated board and plaster so it matches the ceiling. Where the roof insulation is thick, the sides of the well need insulating too, or the cold from outside reaches the plaster and condensation can form in winter. We plan the lining at the survey so the finish inside is part of the written quote and not a surprise for the plasterer.

New roof or existing roof

Forming an opening in a new extension and cutting one into an existing roof are different jobs. The first is part of the build and the lantern arrives at the right moment. The second means working over a finished room, with dust sheets down, props in place and the weather watched. For a straightforward single rooflight the roof work is usually one day or two. A lantern is a larger and more complex piece of work, and the survey tells you what yours involves.

What shapes the quote

Every lantern is quoted after a survey, in writing, and the figure stays put on the day. Two lanterns of similar size can be priced quite differently, because the things that move the cost are not only about size. The list below shows what pushes the figure up or down, so you can see why before you see the number.

Callout 5

Lantern, flat rooflight or roof window

A roof lantern is one answer to a dim room, not the only one. Flat rooflights sit lower, look quieter from outside and suit smaller openings. Roof windows suit pitched roofs and lofts. Sun tunnels carry a little light down a long shaft to a hallway or landing. Choosing between them is a matter of the roof you have and the spot you want to light, and it helps to see the options set out together.

On a flat-roofed single-storey extension, the real choice is between a lantern and one or more flat rooflights. A lantern raises the glass, sends light in every direction and gives the room a ceiling with height and character. A flat rooflight sits close to the roof, takes less room on the outside and is simpler to form. Our flat roof rooflights page covers that side of the choice, including how single-storey extensions can be lit by a row of smaller units instead of a single large one.

Lantern or VELUX windows

A common question is whether to put in a lantern or a pair of VELUX windows. On a pitched roof, VELUX windows are the natural choice, and on a flat roof they need a framed upstand of their own. The two do different things. A roof window opens and gives a view as well as light; a lantern lets light in from several directions and rarely gives much of a view. Our comparison of a roof lantern or VELUX windows goes through the differences in more detail. If you are weighing up the VELUX range itself, see our VELUX windows page.

Heat and comfort

A frequent worry about lanterns is whether the room will get hot. It can if the glass is wrong for the roof, or if the roof faces south with no way to let warm air out. Solar control glass, an opening vent and a sensible size cure most of that. Blinds, fitted inside the lantern, add another layer of control. In winter, the same glass keeps the heat in or lets it out depending on its specification. We deal with this in detail in our answer on whether roof lanterns get hot, and the short version is that glass choice does most of the work.

Orangeries and conservatories

An orangery is built with a flat perimeter roof and a lantern in the middle, so a lantern is the natural choice there. The perimeter has to be insulated and strong enough to carry it. Replacing an old glazed roof on an existing conservatory is a different job, and the walls and frame need checking before any lantern is considered. Our page on putting a roof lantern on an orangery roof explains what the structure needs.

Commercial and residential

Our work is residential first, which means houses, extensions and garden rooms, though small commercial jobs are welcome. A shop back room, a studio or a small office with a flat roof can take a lantern in the same way as a kitchen. The difference is usually in the access, the fall protection and the paperwork rather than in the product.

A lantern or a flat rooflight?

Roof lantern

Raised glass, light from four sides
Gives the ceiling height and shape
Suits wide, deeper extensions
Heavier, needs a stronger kerb

Flat rooflight

Low profile, neat from outside
Simpler to form in the roof
Suits smaller or narrower spots
Less sky, less ceiling drama

Callout 6

Planning, regulations and sign-off

A roof lantern changes the roof, so two sets of rules can apply. Planning is about how the house looks and its effect on neighbours. Building Regulations are about how the work is built, covering structure, insulation and safety. They are separate, and passing one does not cover the other.

Planning

Houses normally get their rooflights through permitted development, with Class C setting the terms. What applies depends on the house, its position and whether it sits in a conservation area or is listed. We explain where your house stands at the survey, and our guide to skylight planning permission in Derby sets out the conditions with links to the source. A flat or maisonette cannot rely on householder rights at all. For a listed building, most alterations need listed building consent first. Inside a conservation area the council may have withdrawn those rights with an Article 4 direction, so ask it before you plan anything. For Derby, the planning authority is Derby City Council, and its pages at derby.gov.uk are the place to start. The national Planning Portal also sets out the process.

Building Regulations

Opening up the roof for a lantern is itself building work, so approval under the Building Regulations is required from the council's building control team or a registered building control approver. Our team deals with the Building Control notification on notifiable jobs and fits to current Building Regulations. Part L treats a like-for-like swap as controlled fitting, with the new unit held to the same 2.2 W/m²K figure. Replacement jobs also have a self-certification route through competent person schemes.

Survey to sign-off, in six moves

Free survey
Someone visits, marks your spot on the plan and studies the roof. Pricing waits.
Written quote
A fixed quote follows, with the glass, upstand and finish itemised.
Made to size
The lantern is measured from the finished opening and built to fit.
Opening and kerb
The roof is opened, trimmed and built up, and the covering is dressed.
Glazing set
The lantern is lifted into place, fixed, flashed and sealed.
Sign-off
We handle the Building Control notification and give you the guarantee.

England's Building Regulations set no daylight standard for houses, so a lantern is never needed to satisfy a rule on light. It is there because you want the light.

From survey to guarantee

The process is the same for every lantern. The free survey comes first, with the room, the place in it and the roof all seen before a price. A fixed written quote follows, and nothing moves on the day. The Building Control notification is dealt with wherever the work is notifiable. The lantern is made to size and fitted, with any scaffold or lift plan agreed beforehand. At the end you receive a 10-year workmanship guarantee in writing, along with the completion paperwork.

We cover Derby and about thirty road miles around it, measured by road. If you would like a lantern looked at, book your free survey, or use WhatsApp, 07880 284133. Email is info@skylarkskylightsderby.co.uk. Give us a rough idea of the room and tell us which spot in it matters most. That is enough to get started.

Planning and Building Regulations are separate rules. Passing one does not cover the other.

Before you book a lantern survey

Can a roof lantern go into an existing flat roof?

Yes. The joists are propped, cut and trimmed around a new opening, an insulated upstand is built and the covering is turned up its sides. We check joist size and direction at the free survey, along with the condition of the covering, and the findings go into the fixed written quote before any work starts.

Will a lantern make my kitchen too warm in summer?

It can if the glass is wrong for the roof. A south or west-facing roof does best with solar control glass and an opening vent, which lets warm air leave. A sensible size matters too. Our answer on whether roof lanterns get hot goes into the detail.

Does a roof lantern need Building Control sign-off?

Yes, in the usual case. Forming a new opening alters the structure, so the work is notifiable and approval comes via the council or a registered building control approver. The notification is dealt with for you, and completion paperwork arrives with the guarantee.

What is the difference between a lantern and VELUX windows?

A lantern is a raised glazed roof for a flat roof, lighting the room from several sides. A VELUX window is a roof window set into the slope of a pitched roof, which usually opens and offers a view. See roof lantern or VELUX windows for the full comparison.

Can a lantern sit on top of an orangery?

Yes. An orangery roof is a flat perimeter around a central lantern, so the lantern is the natural centrepiece. The perimeter must be insulated and strong enough to carry the frame. Read more on fitting a roof lantern to an orangery.

How big should the lantern be for my room?

It depends on the floor area, the ceiling height and the spot you want to light, plus the margin of flat roof the drainage needs around it. We work through it at the survey, and sizing a roof lantern sets out the method.

Book your free survey

Where do you want the light? Tell us in the form: the worktop, the stair, the desk.

No obligation. We survey before we price.
We cover Derby and 30 miles around.