Flat roof rooflights in Maidstone
A rooflight set into a flat roof puts daylight straight down onto the floor of rooms that have sky above them and no wall to borrow light from. We survey the roof, build the kerb, fit the glass across Maidstone and the 30 road miles around it.
- Free survey, fixed written quote
- 10-year workmanship guarantee
The long read
Flat roof rooflights: kerbs, glass, rules and fitting
Under a flat roof there is usually a room that was added to the house later: a utility, a converted garage, a hall in a single-storey wing, a bedroom in a flat-roofed dormer. Each has sky directly overhead and a ceiling that keeps it out. A rooflight in that ceiling is a small structural job as much as a glazing job, because the kerb, the fall of the roof and the glass all have to agree. To talk through your own roof, get in touch.
Rooms that sit under a flat roof
Flat roofs often cover the parts of a house that came after the original build. A single-storey wing, a garage with a room made out of it, a porch, a utility behind the kitchen and a dormer cheek on a loft are all common places for one. The ceiling is low, the walls are shared with older rooms, and the windows that remain are small or face a side passage.
That arrangement makes the roof the one surface that always has daylight on it. A flat rooflight makes it a light source for the room beneath, without moving a wall or touching the front of the house.
Rooms we look at under flat roofs
Converted garages, utility rooms, boot rooms, single-storey hallways, ground-floor shower rooms, garden rooms, porches and flat-roofed dormers.
Natural light, brightness and wellbeing
Light from above lands on the floor and the work surfaces, which is where you use a room. A utility with a single small window beside the back door is bright for the first metre and grey beyond it, so the washing machine and the ironing board live in a dim corner. One rooflight over that corner changes the whole feel of the room, and the same applies to a converted garage with its old door bricked up and a single window facing the neighbour's fence.
Brightness also follows the day. Overhead glass sees the sky in every direction, so a room under it keeps some daylight on an overcast afternoon when a wall window facing the wrong way has already gone dull. Daylight also lets you see the true colour of paint, fabric and food, which matters in a kitchen or a room used for hobbies.
Garage conversions, utilities and flat dormers
A garage converted into a playroom or an office has one end wall with a window and a long side wall shared with the house. A rooflight placed in the middle of the ceiling lights the part furthest from that window. A utility or boot room attached to the back door often has no window at all in its inner half, and a small fixed unit over it gives you a room you do not need the lamp for in the morning.
A flat-roofed dormer on a loft usually holds a window in its front face and a tight space behind it. A rooflight in the dormer roof lights the landing end of the room and gives the bedroom depth. Because the dormer sits well above ground level, the unit is usually out of sight from the street and the garden.
Where a rooflight is the wrong answer
A flat rooflight does little for a room two floors below the roof, and it cannot reach into a space under a pitched roof further along the house. For a windowless landing or bathroom under a pitched slope, a sun tunnel or a roof window is the better route, and over a deep extension, or on an orangery or conservatory roof being rebuilt, a roof lantern suits better. Where a flat roof is close to the end of its life, we suggest it is renewed first, because the covering around the kerb is the part that keeps the new unit watertight.
Fixed, opening and walk-on units
Fixed glass is the simplest unit to understand: a sealed double-glazed pane in a frame, bonded to a kerb, with nothing to open and nothing to maintain except the surface of the glass. It suits any room where light is the only need, and it gives the slimmest line from the garden.
| Unit | How it works | Where we put it |
|---|---|---|
| Fixed rooflight | Sealed pane on a kerb, nothing moves | Hallways, utilities, bedrooms, garden rooms |
| Manual opening | Hinged vent worked with a pole | Bathrooms, shower rooms, kitchens |
| Electric opening | Motor and rain sensor on the vent | Out-of-reach roofs, wet rooms, large extensions |
| Walk-on glass | Laminated, load-rated glass floor in the roof | Terraces, paths, courtyard light wells |
Can you put skylights on a flat roof?
Yes, and flat roofs are one of the easier places for them. The roof surface is level, so the frame sits square on a kerb and there are no tiles or slates to cut around. What changes from roof to roof is the structure under the covering, the existing fall and the covering itself, and we read those at the survey before we agree a product.
What is the best skylight for a flat roof?
The best one is the one chosen for the room. A bathroom needs a way to clear steam, a landing needs light without a view, and a home office needs glare under control. We start from what the room is for and where the light should land, then pick from fixed, opening and walk-on units. Within each type we fit VELUX and other brands from their standard ranges, and we can order a made-to-measure aluminium rooflight where the opening is an unusual size.
Opening rooflights
An opening unit lifts on a hinge, by hand with a pole or with a motor. Hot, damp air rises, so a vent in the ceiling clears a bathroom or a kitchen faster than a window at head height. Motorised units can carry a rain sensor that shuts the vent when a shower starts; we cover the controls and the power supply on the electric opening rooflights page. If you want to stand on the roof or keep the vent clear of furniture below, the position of the hinge matters, and we mark it on the survey drawing.
Walk-on rooflights
A walk-on unit is a thick, laminated glass floor set into a roof terrace or a path to a plant room, or over a basement-style light well. The glass is specified for the load it will carry and the way it will be used, so a unit that people cross to reach a balcony is not the same unit as one over a stair. Our page on walk-on rooflights goes through the types in more detail.
Glass or polycarbonate
Glass gives a clearer view of the sky and holds its look for longer; polycarbonate is lighter. How each behaves with heat is covered in our answer on glass or polycarbonate for heat, and what we fit on a given roof depends on the span, the room and the budget you set.
Upstands, kerbs, falls and drainage
A flat roof is rarely level. It is usually built with a gentle fall so that rain runs to a gutter or an outlet, and any rooflight sitting in it has to leave that route clear. A kerb or upstand that sits across the line of the fall can hold a small pond of water behind it, and ponding is where weather finds the joint between glass and roof.
Building up a kerb
- Set out the opening Mark it on the roof and below, and keep it clear of outlets and the line of the fall.
- Trim the structure Fit timber trimmers or a beam round the cut joists.
- Build the kerb Raise a timber or insulated section square and level on the deck.
- Dress the covering Take the membrane, felt or GRP up the outside of the kerb under the cap.
- Seat the frame Fix, seal and glaze the unit on the finished kerb.
What a kerb does
The kerb is a raised frame, in timber or in a factory-made insulated section, built around the opening. It lifts the glazing above the surface of the roof so that water running over the covering never reaches the frame, and it carries insulation between the warm room and the weather. The roofing membrane, felt or GRP is dressed up its outer face and finished under the cap. Done well, the kerb is invisible once the unit is on; done badly, it can let water in.
The height of the kerb comes from the roof covering and the insulation, not from a single number we apply everywhere. A roof with insulation sitting above the deck needs a different upstand from one with insulation between the joists, and an older felt roof with a deep layer of earlier repairs presents a third case. We measure the build-up at the survey and set the kerb height to suit it. If you want the full detail, the guide on rooflight upstands and kerbs goes through the options.
Falls, outlets and where the water goes
Before cutting anything we look for where the roof drains. If the nearest outlet is on the far side of the opening, the covering around the kerb is shaped to guide water round it. On a roof with a very slight fall, a small tapered section behind the kerb, sometimes called a cricket, can send water to either side. Where the fall runs the other way, we usually leave the arrangement alone.
Outlets and gutters need to stay clear of leaves after the work. A rooflight that has been fitted properly can still be let down by a blocked outlet beside it, and we point out where yours are before we leave.
Reaching the structure underneath
A rooflight needs an opening through the deck and the joists. Smaller openings between existing joists may need only timber trimmers; wider ones, or an opening that cuts a joist, can call for a beam or a steel section. The structure is checked as part of the survey, and any strengthening shows on the quote as its own line. You can read more about this in our answer on adding a skylight to an existing roof.
The ceiling below matters too. The opening in the roof and the opening in the ceiling are joined by a lining, the shaft, and we angle or splay it where we can to spread the light across the floor and reduce the dark edge you get from a straight box.
Frames, glass, heat and security
Look at a rooflight from inside and you notice the light first and the frame second. From outside, the frame is what the neighbours see. It is worth choosing both together.
Myth
Putting more glass in a roof always makes the room hot in summer and cold in winter.
Fact
A current double-glazed unit has to meet the 2.2 W/m²K limit, and solar control coatings or an opening vent deal with the sun, so the room is shaped by the specification and not by the glass alone.
Aluminium frames and uPVC
Aluminium frames are stiff, so the sections can be slim and the glazed area large. They come powder-coated, usually in a grey or black outside and white inside, and a thermal break inside the section keeps the frame's inner face warmer than the air outside. uPVC frames are bulkier, with reinforcement in the section, and they suit a room where the existing windows and doors are white uPVC and a matching finish is wanted. We show you samples at the survey so you can hold them against your own window frames.
Double glazing and the U-value
Double glazing is the starting point. A sealed unit with a low-emissivity coating, a warm-edge spacer and gas fill is the usual build. Part L of the Building Regulations sets the energy limit for a rooflight in an existing home at 2.2 W/m²K, and that is judged for the whole unit with the frame included, not for the middle of the glass alone. We quote whole-unit values so that two rooflights can be compared like for like. A lower figure means less heat escapes. For a longer read on the numbers, our page on energy-efficient rooflights goes through them.
Sun, glare and overheating
Glass facing south or west takes the sun for much of the day, and under a flat roof the heat has nowhere to go. A solar control coating cuts the heat the glass lets in and still passes the daylight, and some versions carry a tint. A rooflight on a north-facing roof can be left clear to keep the soft light. An opening vent, or a blind fitted inside the unit, gives you control when the weather is hot. If you are worried about the room heating up, our answer on whether rooflights overheat a room explains what to ask for.
Safety glass and security
We specify safety glass for a roof: a laminated inner pane, which holds the pieces together if it breaks, and a toughened outer pane. A laminated inner pane also resists forced entry, and a frame fixed from inside with the glazing beads out of reach adds to that. A single-storey roof that can be reached from a garden wall or an outbuilding is the one to think about; tell us at the survey and we will specify accordingly.
Self-cleaning outer glass breaks down dirt in daylight and lets rain wash it away. It helps on a roof that is hard to reach, though a unit that sits under a tree will still need an occasional rinse from a water-fed pole.
Planning, Building Regulations and the paperwork
The question people ask first is whether a skylight on a flat roof needs planning permission. The answer depends on the unit, the house and the council, and we check all three before we price.
Terms from the council and the paperwork
- Class C
- The permitted development class that covers rooflights on houses in England.
- Article 4 direction
- A local direction withdrawing certain permitted development rights across a named area.
- Original roof plane
- The surface of the roof as first built, from which the 150 mm limit is measured.
- Notifiable work
- Work the council or a registered approver must be told about before it starts.
Do you need planning permission for a skylight on a flat roof?
Rooflights on a house in England are usually covered by permitted development under Class C. On a flat roof the condition that bites is height. Measured from the original roof surface, the frame may rise only 150 mm, and on a rooflight that sits on a kerb, the kerb's height counts toward that figure. A low-profile fixed unit can sit inside the figure and a taller one cannot. Lanterns stand higher again, so they usually go to the council for an application. Our answer on planning for a flat roof skylight goes through the points, and the skylight planning guide sets out the full rules.
In a flat or maisonette the householder rights do not apply, so the route is different. A conservation area does not by itself take Class C away; only an Article 4 direction does. If your house is listed, a new opening in the roof will almost certainly need listed building consent. A condition on the original planning permission can also have removed the rights, so check your paperwork. We look at these at the survey and never promise an outcome, because the council makes that decision.
Building Regulations
Cutting through a roof deck is building work: the joists, the energy performance of the room and sometimes fire and escape are all involved. We handle the Building Control notification where the work is notifiable. Inspection and sign-off belong to the council or a registered building control approver. When it is done you get the completion paperwork to keep with the house.
On a replacement, the new unit still has to meet the current limit. A new or replacement rooflight on a kerb takes 2.2 W/m²K. A roof window set in the plane of a pitched roof takes the window limit of 1.4 W/m²K, which is why we treat the two products differently. The full picture is in the skylight Building Regulations guide.
Escape and the ground-floor rule of thumb
A rooflight over a ground-floor room does not usually raise any escape question, since a door and a wall window serve for that. Over a loft room it can, and the height of the floor above ground decides which route the regulations accept. We cover this when the room is in the roof.
What a flat roof rooflight quote is made of
The glass is the part you see, but the quote also carries the kerb, the covering, the structure and the inside finish. Reading the lines in the right order shows why two quotes for a similar-looking unit can differ.
| Quote line | Decided by | Looked at |
|---|---|---|
| Unit size and type | The room and where the light should fall | Survey, inside |
| Kerb and covering | The roof build-up and its fall | Survey, on the roof |
| Structural work | Joist direction and the opening width | Survey, from the loft or ceiling |
| Notification | The council or a registered approver | Before work starts |
Size, shape and the glass
A larger opening needs more glass, a stronger frame and sometimes a beam. A long, narrow unit costs differently from a square one of the same area because of the span the frame has to carry. Glass choice moves the figure as well: solar control, self-cleaning, laminated inners and a thermally broken aluminium frame all add to the specification. For the full list of what a specification includes, see the guide on what a flat roof skylight costs.
The roof around it
The covering decides how the kerb is finished. Single-ply membrane, felt and GRP are each dressed up a kerb differently, and a roof with a warm build-up needs a different kerb section from a cold one. If the covering is near the end of its life, we suggest the roof is renewed first so the new rooflight is not set into old material.
Structure, access and inside work
Smaller openings often need only trimmers. A wider one may need a steel beam, and a bearing or a wall below may need to be checked. Access is a line too: a single-storey roof reached from the garden is quick to work on, while one behind a terrace needs a different method for getting glass and kerb sections up. Inside, the ceiling lining and the plaster finish around the shaft are listed and priced as part of the job, so the unit does not arrive in a half-finished room.
What the quote should name
A good written quote names the unit, its size, the frame and glass, the kerb, the structure, the inside finish and the notification route. Our costs page lists what moves the price for every product we fit, and what it takes to replace a rooflight covers the like-for-like case.
What moves a flat rooflight price
- Opening sizeWider and longer openings need more glass and stronger framing.
- Frame and glassAluminium or uPVC, solar control, self-cleaning and laminated inner panes.
- Roof coveringMembrane, felt or GRP, and the build-up it sits on.
- StructureTrimmers, a beam, or a check on a wall or bearing below.
- AccessHow glass and kerb sections reach the roof.
- Opening gearManual vent, or motor, wiring and rain sensor.
Survey, fitting day and replacement
We start in the loft or at the ceiling and finish on the roof. A free survey takes in the room you want lit, the covering and its age, the structure over the ceiling, the position of outlets and the route we will use to get glass up. Afterwards comes a fixed written quote that lists each of those, with the Building Control notification included where the work is notifiable.
Sent with the survey
A drawing of where the unit sits, its size, the frame and glass, the kerb and covering, any structural work, the inside finish and the notification route.
On the day
Fitting begins inside, with floors and furniture covered and dust screens in place. On the roof we strip the covering back around the opening, cut and trim the structure, and build the kerb. The membrane goes up the outside of the kerb, the frame is fixed and glazed, and the cap is sealed. A small fixed unit on an easy roof can be watertight in a day. Larger or opening units, and anything with a beam, take longer, and we say how long when we quote. Inside, we line the shaft and leave it ready for plaster and paint.
Replacing an old rooflight
Where an older unit has gone cloudy, started to drip or lost its seal, we replace the whole unit. That usually means taking off the old frame, checking the kerb and re-insulating or rebuilding it so it suits the new frame, then fitting the new unit to the current 2.2 W/m²K limit. Glass-only swaps are sometimes possible, and we check the frame for fit. If your unit is misted, the page on misted rooflight replacement covers the signs and the options.
Areas we cover
We work in Maidstone itself and in the towns and villages within about 30 road miles. Close to the town that includes Bearsted, Coxheath, Aylesford and Larkfield. Further out we work in West Malling, Snodland and Staplehurst, and the full list is on the areas we cover page.
How to start
Use the quote form to book a survey. Say which room it is, what the roof is covered in and whether the roof has been touched in recent years. A WhatsApp message to 07880 284133 with two photos, one of the room and one of the roof, works too, as does an email to info@orchardskylightsmaidstone.co.uk. A photo helps us bring the right equipment, though the survey comes before any price. When you accept the quote, our 10-year workmanship guarantee is put in writing.
Flat roof rooflight guides and answers
Price, permission and condensation
What decides the price of a flat roof skylight in Maidstone?
The opening size, the frame and glass, the kerb and covering, any beam or trimmers, how we reach the roof and the inside finish. Our cost guide walks through the lines.
Which flat roof rooflights fall outside permitted development?
Any unit that, with its kerb and frame, stands more than 150 mm above the original roof plane. A roof lantern usually does. A low fixed unit on a shallow kerb may not. The council decides.
Should the rooflight in my flat-roofed bathroom open?
A vent that opens clears steam far faster than a fixed pane, since warm damp air collects at the ceiling. A manual vent needs reaching with a pole; a motorised one can sit out of reach and close itself in rain.
What happens to the flat roof while the rooflight is being fitted?
We strip the covering back only around the opening, build the kerb, then take the membrane or felt up its outside before the frame is fixed. The roof is weathered over the same day it is opened.
Our garage roof is old felt. Can the rooflight go in before we re-roof?
The kerb is dressed with the covering around it, so a worn felt roof is a poor base for a new unit. Often it is best to renew the covering first or at the same time. We look at the felt, the deck and the falls at the survey.
Why does my rooflight glass run with water on cold mornings?
Water on the inside face is usually warm room air meeting cold glass. A modern frame with a thermal break, an insulated kerb and a window or vent that clears steam all help. Mist between the two panes of glass is a failed seal and needs the unit replaced.
Book your free survey
Tell us about the room that stays dark. We come out, look at the room and the roof, then send a fixed written quote.
Or on 07880 284133, or call 01622 277162
No obligation. We survey before we price.