Where to position a skylight so the room gets light and stays calm

A rooflight should be placed for the times you are actually in the room. Daylight moves across the roof all day, and a position that is perfect at noon can be wasted at breakfast.

Before thinking about the roof, write down when each room is busy. A kitchen is used early and again in the evening. A home office is used from nine until five, and needs steady light without a bright patch crossing the desk. A bedroom is used when it is dark, and what matters is what happens at first light in June. A stair and landing are used in passing, so they need a general glow rather than a spotlight.

This short list turns into a brief for the survey. It tells us whether the rooflight should be generous and central, small and high, or pushed to one side of the room. It also tells us where not to put it. Rooms that are used at dusk do not gain much from glass that only works at midday.

A sloping rooflight collects a good deal more daylight than a vertical window of the same size, because it faces the brightest part of the sky. That is why a single well-placed unit can do the work of two windows. It is also why a poorly placed one is so noticeable. Put it in the right spot and the room brightens evenly. Put it in the wrong spot and you get glare in one place and gloom in another.

Orientation sets the character of the light. A roof slope facing south, east, west or north gives four quite different rooms under the same pane of glass.

In the northern hemisphere a south-facing slope receives direct sun for most of the day, and the light is strong, warm and moves across the room. North-facing slopes receive no direct sun for most of the year, and the light is cool, even and steady, which suits studios, offices and kitchens where colour matters. East-facing glass is bright early and dim by afternoon. West-facing glass is gentle in the morning and strong, low and golden in the evening.

None of these is a fault. A north light that feels flat on a grey January morning is the same light that keeps a desk free of shadows in July. The aim is to match the aspect to the room, and where the roof gives no choice, to adjust the size, the glass and the blind to suit.

A flat roof is different, because the rooflight itself can be angled. A lantern has faces in several directions and collects light from all of them. A flat rooflight sits horizontal, looks straight up and takes the sky overhead, which gives a softer, more even fall of light than a tilted one. We describe the choice between the two in our page on how to choose a rooflight for your home.

Each room has a spot where light earns its keep. Find that spot first, then place the glass above it or just beside it.

In a kitchen the worktop and the island are the working surfaces. Glass directly over the island lights it from above and leaves no shadow from the person standing there. Glass set between the island and the window wall lights both and fills the dark middle of the room. Glass placed directly above wall units tends to light the cupboard doors and little else, so we keep the light well clear of the run of units and of the extractor hood, which needs solid ceiling to fix into.

In a bedroom the question is different, because the bed is where the light should not land first. A rooflight over the foot of the bed lights the room when you are dressing and leaves the pillow end dim. A rooflight on the side away from the head of the bed gives bright daytime light with a gentler start to the morning. The full reasoning is set out in our answer on whether a skylight in a bedroom will wake you at dawn.

On a stair, the best position is over the landing or the turn, where the light can drop down the whole flight. A narrow rooflight set above the stairwell does more than a wide one in the ceiling of the hall, because the stairwell acts like a light shaft. A sun tunnel can do this job well in a hallway where a full rooflight cannot reach, and a sun tunnel is a light pipe that carries daylight down through the roof space.

For a home office, the best position is usually beside the desk, not above it. Light falling across the work surface from one side is easier on the eyes than light falling straight down onto a screen. A rooflight directly overhead on a bright day can put a reflection on the monitor, which is tiring by the afternoon.

• Kitchen: over or just beside the island, clear of the extractor and the wall units.
• Bedroom: toward the foot or the side of the bed, away from the pillow end.
• Stairs: over the turn or the landing, so light drops down the flight.
• Office: to one side of the desk, so the screen stays clear of reflections.

On a pitched roof, height up the slope changes where the light lands inside. A unit set high throws light deep into the room. A unit set low lights the floor close to the eaves wall.

In a loft conversion the ceiling slopes down toward the eaves, and a rooflight low in the slope lights the part of the room where the ceiling is lowest, which is usually the part you would otherwise leave dark. A rooflight high in the slope lights the middle of the floor, where the headroom is best and the furniture stands. Two units, one low and one high, often work better than one large unit in the middle, because the light arrives from two heights and softens the shadows between them.

Distance from the side walls matters as much. Glass pushed hard against a gable wall lights that wall and bounces light across the room, which is useful when the wall is white. Glass centred in the room gives a balanced fall of light but leaves the corners dim. We normally check both positions against the furniture plan before settling on one.

Think, too, about the standing position under the glass. On a pitched roof, a rooflight set too low can leave the bottom edge at knee height, which makes the room feel enclosed. Set it so the lower edge is at a comfortable height above the floor, and the room feels open without feeling exposed. Our guide to sizing a rooflight for the room covers how the proportions follow from the position.

The best place for the light is not always the place the structure allows. Rafters, trimmers, valleys, chimneys and falls all narrow the choice.

On a pitched roof, rafters run from ridge to eaves at fixed spacing. A rooflight that fits between two rafters needs little structural change. One that is wider than the gap needs a trimmer above and below, and a cut rafter each side, which is a normal job but one to plan. Moving the unit a short distance sideways to sit between rafters can save structural work without changing the light very much. A roof window chosen to fit the existing spacing is the simplest route.

On a flat roof, the limits are the joists, the falls and the edges. The joists decide how big an opening is easy and where beams may be needed. The falls decide where water runs, and a kerb placed across the run of water has to be positioned so that water can pass round it. Parapets and abutments need a working margin of deck. The flat roof rooflight installation page covers the detail, and we also keep a chimney breast, a soil pipe or a solar panel in mind, because each of them casts a shadow across the glass at some hour of the day.

Where the work is notifiable, we handle the Building Control notification, and the placement is part of what is checked. The total glazed area in an extension is limited, and the position affects fire safety near a boundary. Our page on Building Regulations for rooflights explains which rules apply, and how the glass area is counted.

Finally, walk the loft or the ceiling void before deciding. A position that looks perfect on the plan can land on a water tank, a flue or a run of cable. We check the void at the survey so that these are found before the opening is cut, not after.

One well-placed rooflight is often better than two badly placed ones. When the room is deep or long, two give a more even spread, and spacing then becomes the question.

The rule of thumb is that light from a rooflight reaches about as far across the floor as the ceiling is high, and then fades. In a room with a tall ceiling the reach is longer. In a low attic it is shorter, which is why long attic rooms often need a unit at each end. Two units spaced about one and a half times the ceiling height apart usually leave no dark band between them. Closer than that, and you are paying for overlap. Further, and the middle goes dim.

Symmetry helps the eye. Two rooflights in line, sharing a centre line with a door or a bed or a ridge, look intended. Two scattered at random look like afterthoughts. We mark out the pair on the ceiling plan and check the pattern from the doorway. The answer on how many rooflights a room needs goes through the count for different room sizes.

Every rooflight position trades light against heat and glare. A position that gives the most daylight may also give the most sun on a summer afternoon.

A south or west slope in a loft bedroom can warm up noticeably in July. The fixes are placed in the design: a smaller unit, a solar control coating on the glass, an external blind, or a position that keeps the glass out of the lowest sun. Moving a rooflight a metre toward the north side of a ridge can make a greater difference than adding an internal blind afterwards.

Glare is a placement problem as much as a glass problem. Bright glass directly in the eyeline of a desk, a television or a cooker hob is tiring. Bright glass above and slightly behind where you sit is comfortable. We ask where the television and the screen will stand before we agree the position.

Blinds are best thought of as part of the position, not as an extra. A blind needs a clear run of ceiling or frame to fit and operate, and a rooflight positioned too close to a wall or a beam can leave no room for the track or the cassette. A blind can also change how a room sounds in rain, and our answer on whether a blind reduces rain noise under a skylight explains by how much a fabric layer makes a difference and where it does not.

Where the glass sits decides what it hears. A rooflight is the thinnest part of the roof, and the rooms that feel it most are the ones used in the quiet hours.

Noise does not arrive evenly. Sound from above falls on the roof surface, and the nearer the glass is to the ridge and the open sky, the more directly it is exposed. Rain on a flat glass pane is heard directly in the room beneath it, and a flat rooflight over a kitchen island puts the drum exactly where people sit. A small unit set toward the edge of the room, with a solid ceiling above the table, puts the same sound at a distance. That is a placement choice, and it costs nothing.

In Crawley, Gatwick is inside the borough, and the flight paths pass over parts of the town and the villages around. Where a room sits under a departure or an approach, we listen for aircraft at the survey and place the glass with that in mind. A bedroom under the route may be better served by a smaller, well-specified unit than by a large one. Our page on rooflights under the Gatwick flight paths sets out the local picture, and the answer on whether you can hear planes through a skylight is the shorter read.

The route of the M23, the A23 and the Brighton main line matters in the same way. A rooflight on the side of the roof facing the road receives more of that noise than one facing the garden, so where there is a choice, the garden slope is the quieter one. On a flat roof extension, rain is the noise to plan for, and our page on reducing rain noise under a flat rooflight goes into the glazing build and the seals.

The position tells us what the room needs. The glazing build does the rest. We choose a laminated acoustic inner pane, the thickness of the panes, the cavity, the seals and the upstand for the noise that room hears, and the choice is written into the quiet spec that comes with every quote. You can read what goes into one on the page about the quiet spec.

A position is only a decision when it has been tested in the room. At the survey we treat the placement as a drawing, a mock-up and a conversation, in that order.

The drawing is a ceiling plan with the furniture, the doors, the light fittings and the structure all shown together. The mock-up is a rectangle of masking tape or cardboard held against the ceiling at the chosen spot, so you can see the size and the edges in the real room. The conversation is about what you noticed: whether the tape sits where the kettle is, where the bed is, and whether the room looks better a hand's width to the left.

Then we check the position against the roof from outside and from the void, looking at rafters, falls, valleys and anything that throws a shadow. If the roof and the room disagree, we say so and suggest the nearest position that works for both. It is usually a small move, and it often improves the result.

When the position is agreed it is written on the quote along with the size, the glazing build and the quiet spec, so the drawing, the glass and the price all refer to the same spot. If you would like us to look at a room, get a quote and we will arrange a survey. Our skylight and rooflight installation page shows how the work is organised from first visit to finished ceiling.

These are the questions that come up once the tape is on the ceiling and the furniture is marked.

Can a skylight go directly above a bed?

It can, but it is rarely the best spot. Light directly overhead lands on the sleeper first thing in the morning. A position toward the foot or the side of the bed keeps the daytime light and softens the start of the day. A blind or a darker tint can help, and the choice is best made with the bed position marked.

Should a rooflight be centred in the room?

Not always. Centring looks tidy on a plan, but the useful place is usually over or beside the thing you do in the room. If the room has a clear focus, such as an island, a desk or a dining table, the light should follow that focus, and the ceiling can carry the difference.

Is it better to put a skylight on the north or south side?

South gives more sun and more heat, and north gives steadier light with no direct sun. For a bedroom or an office, north is often calmer. For a living room that wants warmth, south is lovely with shading. The right answer depends on the room and the hour, which is why we start there.

Does the position change how noisy a rooflight is?

It can. Glass facing the road, the flight path or a flat roof with falling rain hears more than glass on the sheltered slope. Position sets the exposure, and the glazing build sets how much of that comes through. Both are considered together and written down in the quiet spec.