You are standing in a half-finished loft bedroom with a tape measure, and the builder asks which type of roof window you want. A centre pivot, or a top hung? Both open, both shed rain and both come in a range of sizes, so the question feels like a matter of taste. It is not. The two move in different ways, and a window that suits a high wall in a landing can be awkward over a bed, a desk or a bath.
The difference shows itself in small daily things: where the handle is, what you can reach, whether the sash swings into a wardrobe, and how you wash the outside pane without climbing onto the roof. This guide goes through each of those in turn and finishes with a room-by-room way to choose. It applies to new lofts and to replacing an existing window, and the sizes and heights for either type are fixed with the builder before the rafters are cut.
How each one opens
A centre pivot window turns on a horizontal axis at about the middle of the sash. When you lift the handle, which sits along the top edge, the lower half swings outwards and upwards while the upper half swings into the room. The opening is therefore split into two: a gap at the bottom, where air comes in, and a gap at the top, where it can leave.
A top hung window has its hinges at the head, and the sash swings outwards from the bottom like a flap. The handle sits at the bottom edge, so you pull it towards you and push the sash out. The whole sash moves outside the room, which leaves the space under the window clear.
The two types are often confused with a third, the fixed roof window, which does not open at all and is used where light matters more than air. Some makers sell variants with the pivot set above or below the middle. Names vary by manufacturer, and the quote states the exact model.
| Centre pivot | Top hung | |
|---|---|---|
| Hinge | Horizontal axis at mid-height | Along the top edge |
| Handle | At the top of the sash | At the bottom of the sash |
| Movement | Top half swings in, bottom half out | Whole sash swings out |
| Reach to open | Handle is high, so the window is placed lower | Handle is low, so the window can sit higher |
| Cleaning the outer pane | Sash rotates so the outside faces in | Cleaned from inside only as far as you can reach |
Neither type is better. They answer different problems, and the room decides which one fits. The loft guide that sits alongside this one, roof windows for a loft conversion, looks at where the windows go in the first place.
Reach and the room below
Reach is the first practical difference. You operate a roof window from the floor, with an arm raised, and the handle's position decides whether you can do it comfortably. A centre pivot has its handle at the top of the sash, so a window set low in the slope can be opened from a standing position without stretching. If the same window is set high, the handle rises with it, and you may be reaching above your head.
A top hung window has the opposite arrangement. The handle sits at the bottom of the sash, which makes it easy to use when the window is high on the slope and out of reach of a person standing beneath. For a window above a stair or in a tall landing, it is often the more sensible choice. Where a handle would still be too high, most makers offer a control bar, a rod that hangs from the sash to bring the handle to a convenient height.
What lies below the window matters too. Over a bed, a desk or a bath, you want the opening to be easy to reach without climbing onto the furniture. Over a stair, the reach is a question of safety, because you will often be standing on a tread, reaching up, in the middle of the flight. In that case an electric or solar-powered opener, run from a wall switch or a remote, removes the problem. Electric units need a cable route at first fix, so they are decided before the ceiling is boarded.
- Low in the slope: centre pivot, handle at a comfortable height.
- High in the slope: top hung, or a pivot with a control bar or electric opener.
- Over a stair or bath: consider electric, so nobody reaches over a drop.
- Out of reach in any room: add a control bar and settle it before ordering.
Headroom and furniture
A centre pivot sash swings into the room, and that has consequences. When it is open, the top half of the sash projects inwards at an angle. If a wardrobe, a shelf or the slope of a ceiling is in that space, the sash can strike it or stop short. So the furniture plan matters as much as the window position.
In practice, the swing means you keep the area beneath the upper edge of the window free of tall pieces. A low bed or a desk is usually fine, because the sash passes above it. A tall wardrobe placed directly under a window may collide with it. If you are not sure, hold a broom handle or a tape out at the angle and see what it would meet, or mark the swing on the plan with the builder.
A top hung sash goes outwards, so the room below is not affected. This is the type to choose when the window is over a place where furniture is likely to be tall, close to the roof slope, or where the slope reaches near the floor and a pivot would catch. The cost is on the outside: the sash projects over the roof when it opens, and the open position needs clear space above it. The opening angle is also limited, so the gap is smaller than the full swing of a pivot.
Another factor is the head of the window, the top edge of the glass. In a loft with a sloping ceiling, the head may sit close to the ridge or to a purlin. A pivot sash needs room to rotate at the top, and if the head is tight against a structural timber, the manufacturer's clearance has to be checked. Our answer on fitting a window between rafters is useful when the window sits close to the timbers.
Cleaning the outer pane
Nobody likes a dirty roof window, and it is the outer pane that gets the weather. Cleaning it is the reason many people choose one type over the other.
A centre pivot can be cleaned from inside. The sash is generally made to rotate through a half turn and hold in that position, so the outer pane faces into the room and can be wiped with a cloth. Some have a catch that locks the sash at the cleaning angle. The method differs by model, so follow the maker's instruction for the unit you have. This is the single biggest advantage of the type for a window in a roof that you cannot or would rather not access.
A top hung window does not rotate, so the outer pane is reached by opening the sash and cleaning what you can from inside. A long-handled tool can reach more, but a large unit may need an outside visit. If the window is on a low or accessible roof, such as a ground-floor extension or a garage, that is simple. If it is high up on a pitched slope, it is not something to attempt without the right equipment.
Glass choice helps. A self-cleaning coating on the outer pane works with rain to break down dirt and wash it off, which reduces the number of times the pane needs cleaning. It does not remove the need entirely, particularly under trees or on a shallow slope. Ask for it in the specification if the window is going somewhere hard to reach, and the quote will say whether the model offers it.
Do not climb onto a pitched roof to clean a window. If the outer pane cannot be reached from inside, a window cleaner with the right equipment, or a different window type at the planning stage, is the safer route.
Blinds and controls
Roof windows gather light and heat, so blinds are part of the design of the room more than an extra. A blackout blind makes a bedroom usable on a summer morning. A pleated or roller blind softens the light over a desk. An external blind or awning cuts the heat before it reaches the glass, which matters in a loft that faces south.
Both opening types take blinds from the same makers, but the type changes how they are fitted and used. The rails and fixings are made to suit the sash, so the blind is ordered for the exact window. On a centre pivot, the handle at the top means the blind control and the opening handle are both near the head of the window. On a top hung, the bottom handle sits where the blind pull might want to be. Check the positions on the sample before ordering.
Controls cover more than blinds. Electric or solar-powered roof windows open and close from a switch or a handheld remote, and some are linked to a rain sensor that closes the window when rain starts. They are useful in a high or awkward position, and they ask for planning: an electric unit needs a power or a solar supply, the electrician needs to know at first fix, and the blind may also be electric.
- Manual blind: a cord or a pole, suited to a reachable window.
- Electric blind: a switch or remote, suited to a high window.
- External awning: controls the heat before it reaches the glass.
- Rain sensor: closes an electric window when it rains, on models that offer one.
The flashing and the weathering of the window are the same whichever type you choose, and our guide to flashing kits for tiles and slate explains how the unit is joined to the covering.
Choosing for each room
There is no need to use the same type throughout the house. A mix is common, and it is often the best answer. Work through the rooms one at a time, ask what the window is for, and let the room choose the type.
| Room | Often suits | Why |
|---|---|---|
| Bedroom | Centre pivot, set low | Easy to reach from the bed and the floor, with the outer pane cleaned from inside |
| Home office | Centre pivot | The desk sits below the sash, which passes above it |
| Bathroom or shower room | Top hung or electric | Steam leaves through the opening and the sash stays clear of the bath |
| Stair and landing | Top hung or electric | The window is high, and nobody should reach from a tread |
| Kitchen or utility | Top hung | Nothing swings into worktops or tall units |
| Under a low slope | Top hung | The sash goes out and does not meet the ceiling |
An opening window gives warm, moist air a way out of a room, which is useful in a bathroom or a bedroom, though it is the whole ventilation arrangement that does the work and not the window alone. Where a window is intended as a way out in a fire, a separate set of rules applies, set out in our answer on roof windows and fire escape.
When you have chosen, the builder needs the type, the exact model and the size in writing before the rafters are cut, because the opening size and the position are fixed by the unit. Our written quote names the model and size, and we time the order so the window is on site when the roof is opened. For the wider range of types, the roof windows page is the place to look.
Opening type questions
- Can I swap a pivot for a top hung in the same opening?
- Sometimes, when the sizes match, but the handle height, the sill position and the flashing can all change. Check the exact models with us before relying on a swap.
- Which type is better in a bathroom?
- Either can work. A top hung sash stays clear of the bath and lets steam out, while an electric opener suits a window that is out of reach. A bathroom should have its own extraction too, because a window alone is not a ventilation system.
- Do both types come in the same glass and sizes?
- Both types come in a range of sizes and glazings, though not every combination is made. The quote names the model and the glazing that has been specified for your window.
