Skylights & rooflights in Bristol Light in. Air through.

This is why the position of an opening rooflight matters as much as its size. One over the top landing or high in a loft room moves far more air than the same unit low on a pitch. In a kitchen extension, an opening rooflight near the back of the room lets cooking heat out without opening the garden doors and letting the cat in. In a bathroom with no outside wall, it gives steam somewhere to go other than the ceiling paint.

Fixed is sometimes the right answer

Not every rooflight should open. A large flat rooflight over a dining table may be better fixed, with an opening unit elsewhere doing the ventilating. Walk-on rooflights are fixed by design. A rooflight over a stair void that nobody can reach is pointless as a manual opener and may only make sense electric. On every quote we show which units could open, how they would open, and where we think a fixed unit is the better call. You decide; we explain the difference.

How the draw runs in different houses

The path the air takes depends on the plan of the house. In a Kingswood or Bishopston terrace the stair climbs beside the party wall and the landing sits in the darkest part of the plan, with bedrooms front and back. A roof window over that stair pulls air in through the hall and the back kitchen, up the flight and out at the top. In a 1930s semi the stair usually rises against the side wall past a landing window, so a roof window in the loft room above works alongside that window rather than replacing it. A Georgian house in Clifton has a tall stairwell rising through three or four storeys, and the top of it is where the pull is strongest. Some of these houses were built with a lantern or a glazed laylight over the stair for exactly that reason, long before anyone used the word ventilation.

A newer house with a single-storey kitchen extension works differently. The air path is short and level: garden doors at one end, an opening flat rooflight at the far end, and the cooking heat goes out over the roof instead of drifting back into the hall.

One thing holds in every house: air needs a way in as well as a way out. A single roof window in a loft room with the door shut airs that room slowly, because the air has to enter and leave through the same gap. Leave the door ajar, or open a window downstairs, and the same unit pulls a steady current through the whole house. Bear that in mind before you choose a size. A modest opening unit in the right place, with a route for air to reach it, does more than a larger one in a closed room.

Opening rooflights also help with moisture. A room that can be aired properly after a shower or a pan of pasta is a room where condensation has a better chance of clearing before it settles on cold glass and plaster. The guide to choosing a rooflight or skylight walks through which type suits which room.

Most roof windows also have a vent bar along the top: a small slot that lets air through while the sash stays shut and locked. Ask about it at the survey, because it gives you a trickle of fresh air overnight without opening the window at all.

Weighing them up

The choice tends to come down to reach and habit. If you can stand under the window and take hold of the handle, manual is hard to beat. It opens as far as you want, it works in a power cut, and there is no battery or motor to think about years from now. The trouble starts when a unit sits high on a landing or near the apex of a vaulted ceiling. A rod works, but a window that needs fetching a rod tends to stay shut, and a window that stays shut does nothing for the air in the house.

Electric earns its place where you want the window to work without you. Controls can open and close several units together, so a rooflight over the stair and one in the loft bedroom can open as a pair on a warm evening, and some systems run on a timer. Because the motor draws power from the house, there is nothing to recharge. The cable route does need planning: in a finished loft it can mean lifting boards or chasing plaster, while in a conversion or extension still at the stud stage the cable goes in before the plasterboard and the extra work is small. The VELUX INTEGRA range covers both electric and solar versions, and other leading makers offer their own.

Solar sits between the two. It suits a replacement in a decorated room you would rather not disturb, and it still charges on a north-facing slope, though more slowly through a grey Bristol winter. If you are torn between the two powered options, the answer on electric or solar sets them side by side, and the one on converting a manual unit explains when an existing window can be motorised later.

Flat rooflights that open are built to shed water even when lifted, with the glass overhanging the kerb so rain runs off rather than in. Roof windows in a pitched roof open outward, so the sash itself keeps most weather off the gap. Neither is something to leave wide open through a storm, but neither is a weak point when it is shut.

Leaving it open safely

Many people want to air a room overnight or while they are out. The vent bar on a roof window allows that with the sash closed and locked. Some roof windows also have a secure ventilation position, where the sash opens slightly and locks there. Electric units can be closed from a keypad on the way out, or from a phone app with some systems.

What the rain sensor actually does

The sensor is a small plate on the outside of the window frame. It reacts to water landing on it, not to a forecast, and when it feels drops it tells the motor to close the sash whether anyone is home or not. That is what makes it reasonable to leave an electric roof window open over a landing while you are at work. Keep the plate clear, because a sensor buried under leaves or moss from an overhanging tree is slower to notice the rain. A manual unit has no sensor at all, so the habit that counts is closing it when you go out and relying on the vent bar instead. The answer on the rooflight rain sensor goes into how they are set up.

The rooflight to think hardest about is the reachable one. A roof window in the back slope above a single-storey extension, or a flat rooflight on a roof someone could climb onto, deserves more care than one high on the front of a three-storey terrace. A key-locking handle stops the sash being opened from outside, and a flat rooflight on an actuator is held shut by the motor arm when it is closed. A laminated inner pane holds together if it is broken. Part K of the Building Regulations does not require laminated glass in a house roof, so treat it as a sensible choice rather than a rule.

Security is about how the unit is fixed and locked rather than whether it opens. A modern roof window is fixed from inside the roof, and its locking handle works like a window lock. Laminated inner glass is an option worth asking about for a rooflight over a bed or a busy kitchen. We set out these options on the quote, so you can choose with the prices in front of you.

If you want an opening rooflight mainly for summer heat, it is also worth asking about glass. Solar control glass and an external awning blind on a roof window both cut the heat that builds up in a loft. Opening the window then clears what is left. Our page on fresh air through the roof goes further into using rooflights to ventilate a whole house.

1930s semis in Henleaze, Westbury-on-Trym, Keynsham and Portishead often have hipped tiled roofs and a box room or a dark landing that would gain more from an opening roof window above it than from anything else. Newer homes in Bradley Stoke, Emersons Green and around Weston-super-Mare tend to have flat-roofed rear extensions, some with an old plastic dome rooflight that is ready to be replaced with something clearer and better insulated.

Stone matters too. Pennant sandstone in the older parts of Bristol and south Gloucestershire, and Bath stone to the east, both carry heavy roofs. The flashing, the kerb and the trimming around a new opening are all chosen for the roof they sit in.

What each roof asks of the fitter

On a Victorian terrace the roof is usually Welsh slate on battens, and older roofs may have no felt beneath them at all. A new roof window brings its own underlay collar, so the area around the frame ends up drier than the rest of the roof, and the slates are cut and dressed to a flashing made for slate. The rafters in these roofs can be slimmer and more widely spaced than modern timbers, so a wider window is framed with doubled rafters and new trimmers rather than simply cut in.

Georgian terraces in Clifton and Bath often hide a butterfly roof behind the parapet, two slopes falling to a central valley. A rooflight on the inner slopes can be out of sight from the street, which helps the conversation with the council, though it does not replace it. Our conservation rooflights page covers the units that suit these roofs, and the Bath page looks at the city's own position.

The hipped roofs on 1930s semis carry clay or concrete tiles, and the hips leave less clear slope than a gable does, so the rear slope is usually where a roof window fits best. Tiles need a deeper flashing than slate, and the battens are set out differently, which the survey picks up. On newer estate houses the main roof is usually built from trussed rafters, the factory-made triangles you see in the loft. These cannot just be cut to make room for a window, so a new opening there needs a structural design first. Their flat-roofed extensions, often in felt or GRP, take a flat rooflight on an insulated kerb, which our flat roof rooflights page explains.

You will find a page for every town we cover on the areas page, each written about that place and its houses.

Replacement is also the cheapest moment to change what the rooflight does. If you have a fixed flat rooflight over a stuffy kitchen, the replacement can open. If a loft window has always been out of reach, the new one can be electric or solar. Because the opening already exists, the extra cost is mostly the unit itself.

Same size, or bigger?

Roof windows come in standard sizes, so an old one can often be replaced with a modern unit of the same size and the same flashing type, with little disturbance to the ceiling inside. Going bigger means trimming the roof timbers, which is more work but often worth it for a loft that has always felt dim. Flat rooflights are usually made to the existing kerb size, or the kerb is rebuilt and insulated to suit a new unit.

What a replacement involves

For a roof window in a pitched roof, the work runs in a set order:

1. The room below is cleared where it needs to be, and the floor and furniture are sheeted.
2. The old sash comes out first, then the frame is unscrewed from the rafters and the old flashing lifted.
3. The slates or tiles around the opening are taken off and set aside for relaying.
4. The new frame is fixed, levelled and wrapped with its insulation and underlay collars.
5. The new flashing is dressed in, the slates or tiles go back around it, and the sash is hung and adjusted.
6. Inside, the lining around the window is finished, ready for decorating.

A flat rooflight follows a different route. The old dome or glazed unit is unbolted, and the kerb beneath it is checked for soft timber and missing insulation, because an old kerb is often the coldest part of the roof. If it is sound it may be insulated and kept; if not, a new kerb is built and the roof covering dressed up its sides before the new unit goes on. Back on a pitched roof, a like-for-like roof window can sometimes be swapped from inside the room, which can save scaffolding on a tall house.

The signs that a unit has reached this point are easy to spot: a grey film between the panes that never wipes away, black mould on the frame, a sash that binds or will not latch, a draught you can feel with your hand, or a brown stain on the ceiling below. Whatever name you use for it, the process is the same. Rooflight is the trade term and skylight the everyday one, and the answer on skylights and rooflights sorts out the difference.

We make the roof weathertight at the end of every day, protect the floors and furniture beneath, and handle the Building Control notification where the work needs one. You can read more on the misted and failed rooflight page, or find out whether a skylight can be replaced without a new roof.

Building Regulations are a separate matter. A new opening in a roof, or a whole new rooflight replacing an old one, is building work that has to meet the regulations, including the energy rules in Part L. For an existing home, the limit is 1.4 W/m²K for a roof window and 2.2 W/m²K for a rooflight. We fit to current regulations and handle the Building Control notification where the work needs one. Replacing only the glass in an existing frame is generally not notifiable. Our Building Regulations guide sets it all out.

Escape is the other rule people ask about. A roof window can only serve as an escape window for a storey within 4.5m of the ground, so in practice it suits bedrooms tucked under the roof of a single-storey or chalet-style bungalow. Converting the loft of an ordinary two-storey home is another matter, because that needs a protected stair down through the house, not an escape roof window. Building Control can be your council's own team or a registered building control approver, and on notifiable work we deal with the notification so you receive the paperwork at the end.

Cost

We do not publish a price list, because the cost depends on the roof, the size and type of unit, how it opens, the access, and the finishing inside. What we can say is what moves the price: an electric or solar unit costs more than a manual one; a new opening costs more than a like-for-like replacement; a conservation rooflight costs more than a standard one; and scaffolding, where it is needed, is a real part of the bill. The costs page gives typical UK ranges and explains each factor. Every quote we send is written, itemised and free.

Timing

A like-for-like roof window replacement is often a one-day job. A new opening with internal finishing, or a roof lantern on a new extension, takes longer, and the survey is where we set a realistic timescale for your house. See how long it takes to fit a skylight for the usual stages.

The wait before the work starts depends on the unit more than the fitting. Standard roof windows in common sizes are widely held by suppliers. Made-to-measure flat rooflights, conservation units and roof lanterns are built to order, so there is a gap between signing the quote and the fitting day. If planning permission or listed building consent is needed, that decision comes first and nothing is ordered until it is in hand. Weather plays a part too: we will not open a roof in driving rain, and a day lost to a storm moves the job rather than leaving your roof half done. In towns further out such as Clevedon or Portishead the timings are the same as in the city.

Whatever the job, the roof is made weathertight at the end of each day, and the work carries our 10-year workmanship guarantee.