The short answer
Often, yes. A failed fixed rooflight can usually be swapped for an opening one in the same hole, provided the kerb or upstand is sound and there is room for the hinge and the sash to swing. The decision is best made before the order goes in, because fresh air, a rain sensor and a motor are simple to specify now and awkward to add later.
What decides whether the opening is possible
Three things set the answer: the size of the hole, the state of the kerb, and what the new sash needs to open without fouling anything.
A fixed rooflight is a pane in a frame with nothing that moves. An opening one has a hinge, a stay or motor, and a sash that lifts clear of the frame, so it asks more of the structure around it. We look at the opening first. If the existing rooflight sits on a timber upstand that is dry, square and firm, a new opening unit can often be sized to the same clear opening. If the old unit was a plain pane dropped onto a thin lip of roof covering, the upstand may need rebuilding to carry a proper frame. That is still replacement work, done in the same visit.
Then there is swing. A roof window on a pitch opens by pivoting or by lifting at the top. A flat rooflight lifts on hinges, and the sash rises at an angle. Both need clear air above the glass. A parapet wall, a dormer cheek or a neighbouring vent pipe too close to one edge can decide which side the hinge goes on, or rule out a particular size. We note these at the survey and draw them into the written quiet spec that comes with the quote.
Finally, the frame. Where the old rooflight failed because the seals gave up, the frame may be fine. Where the frame itself has bowed, split or corroded, there is little point hanging a moving sash on it. Our page on when the frame has failed too explains why a whole new rooflight is the honest route in that case.
Choosing how the new sash opens
Opening rooflights come in three practical forms, and the room decides which one suits.
| Type | How it opens | Suits | Note |
|---|---|---|---|
| Manual | Pole or handle | Reachable windows | Simplest |
| Electric, mains | Motor on a switch | High or flat roofs | Needs a cable |
| Electric, solar | Motor, battery | No cable route | Needs daylight |
Reach matters more than people expect. A manual rooflight over a stair well or a double-height kitchen is a rooflight nobody opens, because nobody can reach the handle. A motor on a wall switch or a remote turns the same unit into one that gets used on an ordinary warm afternoon.
A rain sensor is the small addition that deserves a conversation now. It closes the sash when the first drops land, so a rooflight left open while you are out does not let the room get wet. It is a modest fitting when the unit is ordered and a fiddly one afterwards. Our hub page on electric and opening rooflight installation sets out the control options in full.
What opening adds to a room, and what it asks for in return
An opening rooflight is mostly a ventilation upgrade. The light is the same.
Warm air rises, and a sash set in the highest part of the ceiling lets it leave. In a loft bedroom in August, or a south-facing kitchen extension, that is the difference between a room you use and one you avoid. Purge ventilation of this kind is also what Part F of the Building Regulations looks for in habitable rooms, and a high opening does the job well. A single fixed pane cannot contribute anything.
The price of that openness is sound. A window that lets fresh air in also lets the outside in, and in Crawley that can mean departures from Gatwick on a summer morning or the M23 on a still night. For that reason we specify the sash as a laminated acoustic build and finish the seals carefully, so the closed position is as quiet as a fixed unit would have been. The open position is your choice, and you can use it on the days when the noise is not the point. Our note on failed opening rooflights, hinges and motors covers the moving parts in more detail.
Because the glazing is overhead, it is also laminated on the room side for safety. Safety glazing is covered by Part K, and a laminated inner pane holds together if the glass is ever broken. The page on laminated glass for a replacement unit explains the reasoning.
How the swap is planned and carried out
The order matters, and the survey comes first.
- Measure the opening. We take the clear size, the kerb height and the angle of any pitch. The method is set out in how a failed rooflight is measured.
- Choose the opening method and the glazing build, and write both into the quiet spec.
- Order the unit. Opening rooflights are made to measure, so there is a wait. Lead times vary with the product.
- Fit, weather and make good. The old unit comes out, the upstand is checked, the new rooflight is set and the inside is made good.
Where the work is notifiable, we handle the Building Control notification and install to current Building Regulations. The job carries our 10-year workmanship guarantee.
Questions about swapping fixed for opening
Can I keep the existing frame and just add a sash?
Not as a rule. A fixed frame is built to hold glass still, and it has no hinge points or seals designed for a moving sash. The reliable route is a new opening rooflight that arrives as one matched unit.
Will an opening unit cost more than a fixed one?
Yes, because there is more to it: a hinge, a sash, often a motor and a sensor. We give a clear figure on the quote, and our costs guide shows what moves the price.
Does it need planning permission?
Usually no for a like-for-like opening in the same place, but the position of the roof matters. In a conservation area or on a listed building the answer changes, so we check the address before anything is ordered.
Is a roof window the same thing as an opening rooflight?
On a pitched roof, often yes, since roof windows open by design. Our roof window installation page covers them.
If you would like the new rooflight to open, get a quote and say so. We will write the opening method into your quiet spec. The wider service sits on our misted and failed rooflight replacement page.