Open the centre
Why the middle of a house loses its light, and how glazing in the roof gets it back.
Kent orchardists prune an apple tree to an open centre so sunlight can reach the fruit in the middle. Houses have a similar problem. The middle of a plan goes dark for a handful of reasons, and each has a roof glazing product that suits it.
The idea
Windows sit in outside walls, so the rooms next to those walls get the daylight. Rooms with no outside wall get what leaks in through doors.
The long read
The rooms we are asked to light are the hall, the landing, the utility, the inner bathroom and the lounge that runs deep from front to back. They share one trait: the nearest window is a long way off, or round a corner. Each situation has its own fix, and the rules differ by product.
Light enters at the edges of a house and thins towards the middle.
Terraces and semis of the Victorian and Edwardian years were planned one room at a time, with each room given a window to the street or the garden. Daylight comes in at the front and the back, and the rooms are shallow enough for it to reach the far wall.
Later changes undo the arrangement. Knocking two rooms into one makes a space that is deep from front to back. A side return or a rear extension pushes the back wall further from the old rooms. A garage turned into a study loses the side window. Each change adds floor area and takes light away from the part of the plan that was fine before.
Interwar and post-war houses often have a hall or landing on the line between the front and back rooms, with doors on both sides and no glazing. Bungalows and chalet bungalows have the same pattern, spread across one floor. The hall sits in the middle of the plan, and every other room stands between it and an outside wall.
There is a simple test. Switch the lights off in the room at midday when the weather is clear and stand still for a minute. If you can read the spine of a book on a shelf at arm's length, the room is lit. If you cannot read it until you reach the window, the light has stopped before it reached you.
A rooflight does not depend on the depth of the plan, because it sits directly above the floor it lights. The sky overhead is also the brightest part of the sky on a grey day, which is why a modest opening above a dim room can matter more than a larger window on the far wall.
When you stand in the dark room, look up. If there is a flat roof above, a lantern or flat rooflight can go in. If there is a loft, a roof window or a tube can bring light down. If there is another bedroom above, the answer is a different one, and we cover it below.
Describe the room to us in your first message, and mention what lies above it. That one fact narrows the choice faster than anything else.
Halls and landings that sit away from every outside wall.
A stair that rises between two walls carries daylight up with it only if there is something at the top to let it in. In a two-storey house the stairs often have a window at the half landing or none at all. In a loft conversion the stairs and landing are often the dimmest area of the whole house.
A roof window above a landing sends light down the stairwell to the hall, because the open stair acts as a shaft. The effect depends on the stair layout and the finish on the walls. White or pale walls carry more of the light down, and a dark carpet takes some of it back.
Words for the hall and landing
A bungalow hall is a different case. There is a ceiling, a loft above, and no stairwell. A sun tunnel suits it, with a dome on the roof and a diffuser in the ceiling, and so does a small roof window with a light shaft if the loft is deep enough to build one. A ground-floor hall below a bedroom is the hard one: the bedroom above takes the route, so we look for a way through the neighbouring roof slope or borrow light from the stairwell.
Where the loft is used for storage, the shaft or tunnel runs through it, and we plan the route so that nothing is lost in the loft. Where the loft is boarded and insulated, we check the insulation thickness around the opening so the ceiling does not become the cold spot in the house.
A landing roof window out of arm's reach can be opened by a pole or a motor. A pole is the simpler control, and a motor costs more and needs power.
For more on roof windows see roof windows, and for the tunnel alternative see sun tunnels.
A converted garage or extension is a deep room with few windows.
A garage attached to the side of a house often has one small window and an up-and-over door. Converted to a study, playroom or utility, it is a deep room with its long wall against the neighbour's and its short walls facing the house. Any windows go in the front, and the middle of the room stays dim.
The garage usually has a flat roof or a low pitch, so there are several ways to bring light in. A flat rooflight over a desk, or a long strip of glazing along the ridge of a pitched roof, brings light into the part of the room that the front window cannot reach. For a room with a pitched roof, roof windows set on either slope serve the same purpose.
| Room | Why it goes dark | Usual choice |
|---|---|---|
| Garage conversion | Windows only in the short wall | Flat rooflight or roof windows over the desk |
| Side-return room | Neighbour wall on one side, house wall on the other | Glazed strip down the length |
| Garden room | Glazed doors light one end only | Fixed rooflight over the back |
| Hall behind a bedroom | Room above blocks a direct route | Light shaft borrowed from the stairwell |
A side return, the strip of garden beside a Victorian terrace, is often infilled with a single-storey extension. The new room has a wall on one side that is the neighbour's, and the old house wall on the other. A glazed strip down the middle of the roof often suits it, because it lights the room along the length that has no other window.
Annexes and garden rooms that sit close to a boundary have the same issue on a smaller scale. A garden room with glazed doors at one end is bright by the glass and dull at the far end. A single fixed rooflight above the back of the room is a tidy solution. Because these buildings may not be a house for planning purposes, we check each case rather than applying the usual rule.
The roof matters as much as the room. A felt or EPDM roof can take a kerb. A green roof needs extra thought. A pitched garage roof in concrete tile needs flashings set into the tile pattern, and an old asbestos cement sheet has to be checked and handled safely before anyone cuts it. Tell us what your roof is made of, if you know, and we confirm at the survey.
A lantern usually rises past the 150 mm limit for rooflights, which normally takes it outside permitted development and into a planning application. Our guide to planning permission explains the position.
The roof above the dark space points to the product.
Four products cover the usual cases, and the roof above the dark space usually points to one of them.
Deciding in the room
A lantern is a raised glazed structure on a flat roof. It suits a wide room under a single-storey roof, and it brings light in from four sides and the top. It needs an upstand and a structure that can carry it. See roof lanterns.
A flat rooflight sits on a low kerb. It is the simpler choice when you want less height on the roof or a smaller opening. Some open, and some take foot traffic. See flat roof rooflights.
A roof window sits in the plane of a pitched roof, and a landing, loft room or sloping-ceiling bedroom can use it. See roof windows.
A sun tunnel is a tube with a small dome up top and a light panel at ceiling level. It works for a windowless bathroom, a cupboard or a hall where there is no space for a larger opening. See sun tunnels.
At a survey we also check for a conservation area, the structure of the roof, what is above the ceiling and where the pipes and wires run.
A roof opening is building work, and each product meets it differently.
A new roof opening counts as building work. Structure, heat loss and sometimes fire safety all come into it, which is why we deal with the Building Control notification where the work is notifiable. The local authority or a registered building control approver signs it off.
Planning is a separate question. Roof windows and rooflights on a house are usually permitted development, within limits on how far they stand above the roof and on where they can sit. Lanterns over flat extensions normally fall outside those limits and need a planning application. We check every case at the survey. The guides on planning permission and Building Regulations carry the full detail.
Three checks at survey
Planning route for the product and the house, the Building Control notification, and the framing that has to be trimmed around the opening.
Energy rules shape the choice of unit. For an existing dwelling, a new or replacement roof window has to meet 1.4 W/m²K, or at least Window Energy Rating band B. A rooflight or roof lantern has to meet 2.2 W/m²K. Those numbers decide how much glazing build-up the unit needs.
Escape rules matter for rooms in the roof. A loft conversion above two storeys puts the new floor higher than 4.5 m, so the usual answer is a protected route down the stairs, and the roof window does not count as the way out. A bungalow or chalet room is within the height, and a roof window can serve as its escape if the opening is at least 0.33 m² and 450 mm in each direction, sits no more than 1,100 mm above the floor and stays open without being held.
Building Regulations set no daylight requirement for houses in England, so nobody will ask you to show that a room is bright enough.
Joists and rafters carry the roof, and cutting them without trimming weakens it. The survey includes the framing, and the quote describes the trimming.
What happens between the first message and the finished ceiling.
The first step is a message. Send us the town, the room and what is above it. We come for a free survey, check the roof and structure, and tell you what will work and what will not.
The quote follows in writing at a fixed figure, and you can compare it with any other quote. For the factors behind a figure, see the costs page.
Myth
A rooflight will make the room cold in winter.
Fact
A unit that meets the current Part L limit loses heat at a controlled rate, and the survey sets the specification for your roof.
The fit takes place at a time agreed in advance. We protect the room below and open the roof, set the unit and weather it in, then line the opening and finish inside. A 10-year workmanship guarantee in writing is part of the handover, and our guarantee page explains what it covers and how to claim.
Not every dark room needs a roof opening. A lighter paint, a glazed internal door or a different layout sometimes does the job. If the answer is glazing in the roof, we will have the measurements to hand.
You can send us the details through the form, by email at info@orchardskylightsmaidstone.co.uk, or on WhatsApp at 07880 284133.
Try the book-spine test on a bright morning: if you cannot read a spine at arm's length, daylight is not reaching the hall.
A window on a half landing lights the landing itself. The lower flight and the hall at the bottom are around the corner from it. A roof window above the top landing can send light down the whole stairwell.
A sun tunnel is a tube with a dome on the roof and a panel in the ceiling, and it fits where the route through the loft is awkward. A small roof window needs a light shaft that is wide enough to be built. We recommend the one that suits your loft.
A lantern's height above a flat roof usually passes the 150 mm allowed, which takes it outside permitted development. The planning guide explains it, and we check the position for your house.
A room that already has windows on two sides and is shallow gains little from another source. A rooflight is best where distance from the wall is the problem.
Often a roof window on the slope above the landing does it. We check the pitch and the rafters at the survey, and the escape rules for the bedrooms in the roof.
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.
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