01Short answer
Yes, some can, and some are better left shut
An opening conservation rooflight exists, but it costs you a little of the slim, flat look that people choose this style for.
The classic conservation rooflight is a fixed pane in a thin metal frame, set close to the slope so it looks like part of the roof. Nothing moves, so nothing needs a bulky hinge or a motor. That is the version most people picture, and it is the neatest.
If you want fresh air as well as daylight, there are opening versions. They keep the same slim frame and the same glazing bar pattern, but add a hinge and a handle, a pole, or a small electric actuator. Some are hinged at the top and swing out, others lift at the bottom edge to leave a gap for ventilation. Whether an opening unit suits your roof depends on the slope, the room underneath and, in a protected area, what the council is happy to see from the street.
So the answer to can conservation rooflights open is yes, with a trade. You gain ventilation and give up some of the flush, fixed neatness. We would rather talk that through on your roof than sell you the same unit for every room.
A fixed pane is the tidiest. An opening one is the practical choice where the room needs air.
02Ways to open
How an opening conservation rooflight works
Three ways of moving the glass, each with a different effect on how the roof looks and how the room feels.
On a pitched roof, an opening unit is hinged on one edge and sits in a frame that is a touch deeper than a fixed one, because the moving sash needs somewhere to go. The sash closes onto a seal all the way round, and that seal is what keeps the warmth in when the unit is shut. A good one closes against a compression gasket, much as a modern front door does.
You then choose how it is operated. A handle suits something you can reach from a landing or a stair. A pole is for a unit set higher up. An electric actuator is for a rooflight over a stairwell or a double-height space, where you would never get to it by hand. Our page on electric opening rooflights covers the motorised side, and ventilating with opening rooflights explains why warm air rising out through the roof is such an effective way to cool a room.
Fixed conservation rooflight
The slimmest frame and the flattest profile. No moving parts and the fewest joints, so the best fit for a rooflight you only want for daylight.
Opening conservation rooflight
A slightly deeper frame, a hinge and a handle or motor. Lets stale air and kitchen steam out, and gives you a way to cool an upstairs room in summer.
03Warmth
Does opening cost you heat?
A shut opening unit can be just as warm as a fixed one, as long as the seal and the frame are well made.
This is where most people worry, and it is a fair worry. More moving parts means more places for a draught to get in. A cheap opening rooflight with a thin gasket and an uninsulated frame will be colder than a fixed one beside it. A good one is built with the same warm-edge double glazing and the same insulated frame, with a thermal break in the metal so the cold outside does not conduct straight through to the inside.
The easy rule is to compare the whole-unit U-value, not just the glass. U-value is the rate heat passes through, measured in watts per square metre for each degree of temperature difference, and lower means warmer. Ask for the figure for the complete window with its frame, because a pane that looks excellent on paper can be let down by the edge. We go through the numbers on are conservation rooflights energy efficient.
Fitting matters as much as the product. The frame has to be sealed into the roof build-up, with the insulation carried right up to the opening and a vapour control layer joined to the lining, or a chilly band will form round the opening however good the unit is.
04Your roof
Where an opening one earns its place
Think about what the room needs before you decide, because the best answer is often one opening unit and one fixed.
Bathrooms, kitchens and loft bedrooms are the rooms where opening glass pays back. They gather steam, cooking smells and summer heat. A landing or a stair void mostly just needs light, so a fixed unit does the job and keeps the roof looking calm from the street.
In a protected area there is a second question. Conservation areas do not take Class C permitted development away on their own, but an Article 4 direction can, and listed buildings always need listed building consent. An opening unit sits a little differently from a fixed one when it is ajar, so tell the council what you are proposing. Our page on skylight planning permission sets out how to check, and conservation areas and listed homes in south Essex looks at what that means locally.
- Is the room one that gathers steam or heat?
- Can you reach the unit, or would it need a pole or a motor?
- Will the opening unit be seen from the street?
- Does the council expect a particular style in your area?
- Is the property listed, which needs consent whatever the roof?
Still undecided? Our free survey and written quote lets you compare both options on your own roof, and it comes from Radiant Skylights. Replacing a whole rooflight is notifiable under Part L, and we handle the Building Control notification where it is needed. For the full range, see our conservation rooflights page.
Venting a period roof: the doubts that come up
Do all conservation rooflights open?
No. The standard one is a fixed pane. Opening versions are made, but they are a separate choice with a slightly deeper frame and extra hardware.
Can an opening one be fitted flush with the slope?
It can sit close to the slope, though a moving sash usually needs a little more depth than a fixed pane. We would show you the real difference on your roof before you decide.
Can I have it motorised?
Yes, an electric actuator can be added where the rooflight is out of reach. It is a good fit over stairs and in tall spaces.
Will the council mind an opening unit?
That depends on your area and your building. Check with the council before ordering, particularly for a listed building, where listed building consent is always needed.
