Fixed to opening
Can a fixed rooflight be made to open?
You have a skylight that does not open and a room that needs air. The fix is rarely a hinge added to the old unit. It is a new opening unit in the opening you already have, and the rules follow the house.
The answer
Usually not by adding a hinge. A fixed rooflight is made as a closed, sealed unit with no hinges, seals or space for an opener, so it is replaced by an opening unit set into the same roof opening. A house keeps its permitted development rights if the new unit stays within the Class C limits, while a flat needs the council to be asked first.
Why can't the existing unit just be fitted with a hinge?
A fixed unit has no hinge fixings, no opening seal and a frame that is not built to carry a moving sash. Retrofitting one would leave a weak, leaky window.
A fixed rooflight looks like a window with the handle missing, but it is built differently from the start. The glass is bonded or clamped into a frame that is not meant to move, and the seal runs unbroken round the edge. An opening unit has hinges, a stiffened frame, a gasket that is compressed each time it closes and, often, a drip detail across the top.
What a conversion would need
To make a fixed unit open you would have to cut the glass free, add hinge rails, fit a gasket and a lock, and check that the frame could take the load of a swinging sash in wind. Doing that to an old unit is rarely sound. The glazing seal may be tired already, and a misted or cold fixed unit is often the reason the owner is looking at it again.
The exceptions
A few makers sell fixed and opening versions of the same frame, so the outer frame stays and the sash is changed. That only works within one range, and an old or unbranded rooflight seldom has a matching opening version. At the survey we identify what is on the roof and tell you whether a like-for-like opening sash exists, or whether the whole unit comes out.
What changes and what stays when the unit is swapped?
The old unit comes out and an opening one goes into the same opening, often on the same upstand. The structure, the ceiling lining and the finish round the edge usually stay.
The good news is that swapping a fixed rooflight for an opening one does not mean starting again. The hole in the roof, the framing around it and the finished ceiling can often be reused, provided the new unit is a close match in size.
Size and fit
An opening unit is usually a little deeper in section than a fixed one, because of the sash and hinge. It may need a different upstand height, or a slightly larger opening, to allow the sash to swing clear. We measure on the roof and the ceiling before specifying, so the new unit lands in the old unit's position and leaves no gap to fill.
Flat roofs and pitched slopes
On a flat roof, the old kerb may be reused provided it is sound and tall enough for the new frame. On a pitched slope, the flashing round the unit is renewed with it so that the weathering is matched to the new frame. In both cases the roof covering around the unit is made good as part of the work.
Motor or hand control
The opening unit can be hand-operated or motorised. If you want a motor, our answer on electrical work explains the wiring side, and the extra cost shows up in the quote.
Do the planning and building rules apply to a swap?
On a house, Class C applies if the new unit stays within 150mm of the roof plane and no higher than the highest part. A flat needs the council asked first. Building Control and Part L apply either way.
A swap looks minor from inside the room, but the rules look at the roof, and an opening unit can stand taller than a fixed one.
On a house
A rooflight on a house is permitted development under Class C if it projects no more than 150mm beyond the plane of the roof slope and sits no higher than the highest part of the roof. Compare the height of the proposed unit, closed, with the one it replaces. Where the slope faces the side of the house, the window needs obscure glass throughout, and it cannot open unless every opening part is more than 1.7 metres above the room's floor.
On a flat
Flats and maisonettes have no householder permitted development, so on a Tyneside flat, upstairs or downstairs, treat the swap as a question for the council before you order. Owning a flat? Your lease or title will name who has the roof. Find out what the neighbour has to be asked, and ask, ahead of any order.
Building Regulations
Building work is notified to Building Control, the local authority or a registered building control approver, and we handle that where it applies. Under Part L for existing dwellings in England, the limiting U-value is 2.2 W/m²K for a rooflight and 1.4 W/m²K (or WER Band B) for a roof window. An Article 4 direction or a condition on an earlier planning permission can remove Class C from a house.
What should be checked before a fixed unit is replaced?
Measure the opening, note the roof type, check the finished height, and decide how the sash will be controlled. Then settle the planning route that fits your home.
A few simple steps before ordering avoid a unit that does not fit or a job that needs an application at the last minute.
Measure what is there
Note the size of the existing opening, the depth of the upstand or how steep the slope is, and what lies below. A shelf, a light fitting or a stair rail inside can limit how far a sash can swing. Our page on electric and opening rooflights shows what the sash types look like.
Decide on the control
A pole, a winding handle, a switch or a handset: each suits a different height of ceiling. Choose with the room in mind, as a sash nobody can reach will not be opened.
The free survey precedes any price, the quote is fixed and written, and the workmanship is guaranteed in writing for 10 years; the guarantee itself is described here.
Before a fixed rooflight is replaced
- Is the home a house or a flat, and who owns the roof?
- Will the opening unit stand higher over the roof than the old one?
- Is there room inside for the sash to swing clear?
- Who will operate it, and from where?
- Does an Article 4 direction or earlier planning condition apply?
Swapping a fixed skylight: what else comes up
Can I keep the old frame and just change the glass?
Only if the frame is built for an opening sash, and fixed frames generally are not. Fitting an opening pane into a fixed frame would leave a sash without proper hinges or seals. We assess the frame at the survey and explain what can be reused.
Will the ceiling lining need redoing?
Not if the new unit matches the old one for size, and the inside finish is sound. A larger or deeper unit may need the lining adjusted. We note this at the survey so the quote includes what the swap needs.
Is an opening unit more expensive than a fixed one?
Yes, because of the sash, hinges, seals and any control. How much depends on size, glazing and whether it is motorised, which the survey turns into one written figure. What moves a price is laid out on the costs page.
Could the new unit be a roof window instead?
On a pitched slope it can, if the opening suits and you want a sash that gives a view and a larger gap. A roof window has a different U-value limit under Part L, 1.4 W/m²K or WER Band B, against 2.2 for a rooflight.