Roof lanterns in Maidstone

Lantern, skylight or roof window?

People use the word skylight for all three, which is fine in conversation but muddles the choice. A flat glass rooflight sits low on its upstand and looks almost like a pane laid on the roof. A lantern climbs higher, with glazed sides and hipped ends, so it catches light from a wider part of the sky and lifts the ceiling line inside. A roof window goes into a pitched slope, such as a loft bedroom or the lean-to roof of a single-storey kitchen. If you are weighing a lantern against a pitched-roof window for the same room, our short answer on a roof lantern or a VELUX window sets the two side by side.

What a lantern roof extension looks like

A lantern roof extension is a single-storey rear or side extension with a flat roof and one or more lanterns set into it. The extension makes the house deeper, and the lantern is placed over the part of the new room furthest from its doors and windows, often near the point where it joins the original house. An orangery follows the same idea: a solid perimeter roof with insulation and plaster inside, and a lantern in the middle where an older design might have had a fully glazed roof.

Conservatories are a related case. A full glass or polycarbonate conservatory roof gets hot in July and cold in January. Swapping it for a solid, insulated flat roof with a lantern keeps a generous patch of sky above the room while the rest of the ceiling behaves like part of the house. That change counts as building work, so the frames and base need a proper structural check and the job needs a Building Control notification.

Where a lantern suits the house

The best spots share a pattern: a deep room, a flat roof above it, and an inside wall that used to be an outside wall. Examples include a Victorian terrace with a side-return kitchen, a 1930s semi with a full-width rear extension, and a newer house where a garden room opens off the lounge. In each, the side windows light the edge of the room well and the middle badly.

A lantern is the wrong answer when the roof is pitched, when the flat roof is too shallow to take an upstand without a rebuild, or when the room is narrow enough that a flat rooflight would do the same work at a lower height. In that last case a flat roof rooflight on a low upstand needs less structure and sits closer to the roof line.

Natural light where the plan is deepest

Set a lantern over the half of that garden room nearest the house and the dim band closes up. The seating at the back, furthest from the doors, gets light from above, and the lounge borrows daylight through the wide opening that joins the two rooms. In a kitchen extension the same move puts light on the worktop from overhead, so you are not cooking in your own shadow.

A lantern also does something a flat rooflight cannot. Its glazed sides take in low sun in the morning and evening, and its height adds volume to the ceiling. Standing underneath, you look up into a small glazed room with the ridge at its peak, and that part of the ceiling feels higher than the rest.

Brightness through the day and the year

Facing matters less with a lantern than with a wall window, because it sees sky in every direction. With a north-facing garden, the back of the house gets little direct sun. A lantern still collects the bright overhead sky on a grey December afternoon, and in summer it can be fitted with solar control glass so the room does not overheat.

Wellbeing and the way a room is used

A room where you can watch clouds cross the glass feels different to sit in from one lit by a grid of downlighters all day. Work at the table, homework after school and a wet Sunday at home all happen under light that shifts with the weather and the hour. Daylight also shows true colours, which helps when you are choosing paint, cooking or reading, and our answer to whether roof lanterns are worth it weighs that light against the extra glass and structure.

A lantern lights the room it sits in and the spaces that open onto it. It will not reach a landing upstairs or a windowless hall on the far side of a solid wall; for those, a sun tunnel or a window set into the slope is the better tool.

The measurements we take

Measuring for a lantern starts with the structural opening in the roof: the hole between the joists or beams, trimmed on all four sides. Around it sits the upstand, the timber or insulated kerb built up from the roof, and its outside dimensions set the size of the lantern frame. Then there is the room below, with its width, length and ceiling height, because a lantern that suits the roof can still look wrong from inside.

We have each lantern made to fit the outside dimensions of its upstand. If the upstand is built a little out of square, or a little wider than drawn, the lantern either overhangs badly or does not sit on it at all. On a new build we agree the upstand size with your builder before they make it. On an existing roof we measure what is there, check the corners for square and the top for level, and correct it before ordering.

Proportion from inside the room

A lantern should look as though it belongs to the room. As a rough working guide, we keep a sensible border of plain ceiling around it so the glass sits like a panel set into the ceiling. In a long kitchen, a long narrow lantern running with the room often looks better than a square one. In a near-square garden room, a square lantern with four equal hips sits comfortably. Where a room is very long, two lanterns in a line can be better than one huge unit, because each keeps a manageable span and weight.

Ridge direction is another choice. Running the ridge along the length of the room draws the eye towards the garden. Running it across can line up with a kitchen island. We sketch both on the survey so you can see them before anything is ordered.

Upstand height and the flat roof

The upstand does two jobs. It lifts the glass above the finished roof surface so water runs away from the frame, and it carries insulation between the warm room and the cold air outside. A flat roof build-up with insulation on top needs a taller upstand than an older roof with insulation between the joists. Too low and the roof covering cannot be dressed up the side properly; too high and the lantern looks perched. We set the height to suit the covering, whether that is single-ply membrane, felt or GRP, and the falls of the roof around it.

Structure under the glass

A lantern's glazed units and frame bear on the upstand around the edge of the opening, and the opening itself cuts through the joists that carried the roof there. So the opening needs trimmers, and sometimes a steel or engineered timber beam. On a new extension the engineer designs for it. On an existing roof we check what is there, as our answer on adding a lantern to an existing flat roof describes, and where a calculation is needed it is done before the price is fixed. Strengthening work found at the survey goes onto the quote as its own line.

Aluminium frames or uPVC

Aluminium frames are slim and stiff. Because the metal is strong, the bars between the panes can be narrow, so more of the lantern is glass and less is frame. A thermally broken aluminium lantern has an insulating strip inside each section, so the inside face stays warmer and condensation on the frame is less likely. They come powder-coated in almost any colour, and a dark grey or black outside with white inside is one option.

A uPVC lantern usually costs less to buy. The sections are bulkier, with internal reinforcement to carry the glass, so the sight lines are thicker. On a conservatory refurbishment where the existing frames are white uPVC, a matching uPVC lantern can look right. On a crisp new kitchen with slim aluminium doors, aluminium frames usually suit better. Some lanterns combine both, with an aluminium outer cap over a uPVC or timber-lined core. We show you sections and colour samples at the survey so you can hold them up against your doors.

Double glazing or triple

Double glazing is the starting point for any lantern we fit. A good double-glazed unit with a low-emissivity coating, warm-edge spacer bars and argon fill can meet the Part L limit of 2.2 W/m²K for rooflights, judged on the whole unit with its frame. Triple glazing improves insulation further but adds weight and cost, and on a pitched lantern the extra weight bears on the frame and the structure below. We recommend it where the room is used all winter or where the lantern is large, and check the frame is designed to carry it.

Solar control and glare

A south- or west-facing lantern on a kitchen can let in strong heat on a July afternoon. Solar control coatings reflect part of the sun's heat while letting daylight through, and some come with a tint, blue, grey or neutral, that changes the look from outside. On the north side of a house, clear glass is often the better pick so you keep every bit of the soft light. The coating goes on the quote once we have checked which way your roof faces and what shades it.

Safety glass, self-cleaning glass and security

A well-specified lantern has a toughened outer pane and a laminated inner pane; if the inner pane breaks, the pieces stay bonded to the interlayer and do not fall into the room. Some units also carry a self-cleaning coating on the outside face, which uses daylight and rain to loosen dirt; it helps, though a lantern in the shade of a tree will still need an occasional rinse. Laminated glass also improves security, since it resists being broken through, and internally fixed glazing makes it much harder to remove panes from outside. On a single-storey extension with an easy climb from the garden wall, that detail matters.

Opening vents

A lantern can include one or two opening vents, manual or motorised; the motorised ones work along the same lines as electric opening rooflights, and can be fitted with a rain sensor that closes them when a shower starts. Hot air rises to the top of the lantern, so a vent there clears warm air from the room better than a window at head height.

Planning permission

A house in England usually has permitted development rights under Class C for rooflights, provided the unit, frame included, projects no more than 150 mm beyond the plane of the original roof slope and stays below the highest part of the original roof; a further condition for side-facing slopes is set out in our skylight planning guide. A lantern on a flat roof usually rises more than 150 mm above the roof surface, so it normally falls outside Class C and needs planning permission unless the council confirms otherwise.

On a new extension that already has planning permission, the lantern is usually shown on the approved drawings and the question answers itself. Where we add a lantern to an existing extension, we check the planning history and, where needed, prepare or support the application before work starts. Flats, listed houses and homes covered by an Article 4 direction each change the picture, and our guide to roof lantern planning and Building Regulations takes each case in turn. National guidance is on the Planning Portal.

Building Regulations

Cutting a new opening in a roof and fitting a lantern is building work. The structure has to carry the load, the roof has to stay weathertight, and the glazing has to meet the energy rules. We handle the Building Control notification, and the local authority or a registered building control approver inspects and signs it off. You receive the completion paperwork, which you will want when you sell.

Energy efficiency and the U-value

Part L, the energy part of the regulations, sets a maximum U-value for new and replacement glazing in existing homes. For a rooflight or roof lantern, the limit is 2.2 W/m²K. The U-value measures how much heat escapes through each square metre for each degree of temperature difference, so lower is better. A roof window in a pitched roof takes the tighter window figure of 1.4 W/m²K, which is one reason the two products are specified differently.

The figure that counts is the whole-unit U-value with the frame included; a centre-pane figure for the glass alone leaves the frame out of the sum. Insulation around the lantern matters as well: an insulated upstand and a well-sealed junction with the roof keep the edges warm and reduce the cold bridging that leads to condensation at the frame. For a closer look at glazing performance, see our page on energy-efficient rooflights.

Heat loss through an old conservatory roof

Single-skin polycarbonate and older glass conservatory roofs lose heat far faster than an insulated flat roof, and the same thin roof lets the sun's heat straight in during July. Replacing that roof with an insulated solid one and keeping a lantern in the centre cuts the area of glazing to the part that delivers the light, and the lantern that remains is specified to meet the current limit.

Before anyone climbs a ladder

Once you accept the quote, we place the order for your made-to-measure lantern, and from that point the measurements are fixed. While it is being made, the Building Control notification goes in, any structural design is confirmed, and we agree access with you and, if you share a wall or a drive, with your neighbours.

The installation process on an existing flat roof

On fitting day we protect the room first: dust sheets, floor protection and plastic screens to keep dust in the work area. Then we strip the roof covering back around the opening, cut the joists, and fit trimmers or a beam where the design calls for one. The upstand goes on next, insulated and set square and level. The roof covering is dressed up its sides so water has a continuous path down and away.

The lantern arrives as a frame and glass units. We assemble the frame on the upstand, fix it down, glaze it, and fit the ridge and hip cappings. Seals and flashings are checked before we leave the roof. Inside, the reveals between ceiling and frame are boarded, insulated where needed and finished to take plaster and paint. A small lantern can go from bare opening to watertight in a day; a large one, or a pair, takes longer. We tell you the expected time when we quote.

On a new extension

On a new build, the order changes. The builder forms the opening and upstand to the size we agree, the roofer completes the covering up the upstand, and we fit the lantern when the roof is ready. Agreeing the upstand size before the roofer starts avoids a kerb built a little too big for the lantern that arrives.

Replacing an old lantern

Where an existing lantern has failed, perhaps with misted units, leaking bars or a sagging frame, we remove it and check the upstand before fitting the new one. Often the upstand can be kept and re-insulated; sometimes it needs rebuilding to suit modern frame sizes. Either way you know before the work begins.

After we leave

Building Control signs off the work and you get the completion certificate, with our 10-year workmanship guarantee in writing. Size, glass, structure and access set the price, as the roof lantern cost guide explains, and our costs page covers every other product. Upkeep comes down to clearing leaves from the roof around the lantern, rinsing the glass now and then if it sits under trees, and keeping the drainage outlets clear.

Areas covered around Maidstone

Closest in, we work in Bearsted, Coxheath, Aylesford, Larkfield and Kings Hill. North of the town we cover the Medway towns, including Chatham, Rochester and Gillingham. To the south and west, our areas covered include Staplehurst, Marden, Tonbridge and Royal Tunbridge Wells. East, we reach Lenham, Charing and on towards Ashford.

Each borough has its own planning team and its own conservation areas, and Article 4 directions in some places change what a homeowner can do without permission. We check that council's records for your address as part of the survey.

Free survey and a fixed written quote

Every lantern starts with a free survey at your home. We find where the light stops and where you sit, check the roof's covering, its age and how it drains, look at what lies under it and how we would reach it, then measure the opening or the proposed opening and look at the planning position.

You get a fixed written quote afterwards. It names the lantern, its size, frame material, colour and glass, the structural work, the roof work around the upstand, the inside finish and the Building Control notification. Anything the survey turns up that you need to know first, such as a roof due for replacement or a planning application, appears on it as a separate line.

Getting in touch

Use the quote form at the bottom of the page to book a survey. Tell us roughly where the room is, what kind of roof it has, and whether the extension exists yet or is still being planned. If it is easier, message us on WhatsApp on 07880 284133 with a couple of photos of the room and the roof, or email info@orchardskylightsmaidstone.co.uk. Photos help us bring the right ladders and know which covering to expect before we arrive.

A lantern for an extension still at drawing stage can be sized with your builder before the roof goes on. An orangery or conservatory refurbishment starts with the frames and base, and a replacement starts with the upstand the old lantern sits on. For any of the three, book your free survey.