Does the room change the planning position?
No. Planners judge a conservation rooflight by what it does to the roof, not by what sits under it, so a bathroom unit faces exactly the same questions as one over a bedroom or a landing.
In a Cambridge conservation area that means size, position on the slope, how visible it is from the street, and whether it sits flush with the slates or tiles. If an Article 4 direction applies, or the house is listed, you will need an application or consent before anything is cut, and the fact that it lights a bathroom neither helps nor hurts. Where a bathroom rooflight can gain a small advantage is placement: bathrooms in terraced houses tend to sit at the back, over the rear addition or in the rear half of a loft, so the rooflight often lands on the slope planners are more relaxed about. The trade-off between the slope that gives the best light and the slope planners prefer is covered in front or rear slope, and the wider picture is on the conservation rooflight installation page.
Ventilation: the sash helps, the fan is still required
An opening conservation skylight is a good way to clear steam quickly, but Approved Document F still expects a bathroom to have mechanical extract ventilation, and a rooflight on its own will not meet that.
Part F sets an extract rate for bathrooms (an intermittent fan rated at 15 litres per second is the usual benchmark, with continuous systems as an alternative), and an openable window or rooflight does not stand in for it. The reason is practical: nobody opens a rooflight on a January morning, and a closed sash moves no air at all. So plan the fan first and treat the rooflight as a bonus. Warm, wet air rises and gathers at ceiling level, which is exactly where a rooflight sits, so a sash opened for ten minutes after a shower clears the last of the humidity faster than the fan alone.
A top hung sash on a stay is the usual opening type; the options are set out in can conservation rooflights open. If the rooflight is out of reach above a bath, an electric actuator is worth considering, though the motor, wiring and switch then have to respect the bathroom electrical zones, and whether a given range offers one is a matter for the maker's specification. Background ventilation in slim frames is limited; see do conservation rooflights have trickle vents.
Condensation on a slim steel frame
Bathrooms produce more moisture than any other room, and the inside face of a rooflight is often the coldest surface in them, so this is where condensation shows first.
Modern conservation units are double glazed and some have a thermal break in the frame, which keeps the inner surface warmer than an old single glazed cast iron light ever managed. Some ranges also include a condensation channel that collects droplets and lets them evaporate. Even so, a bathroom without a working fan will run with water on any glass in the roof. Good extract, warm glazing and a properly insulated lining around the opening are what keep the frame dry. The glass and frame detail is explained in thermal performance of conservation rooflights.
Privacy and glass
A rooflight looks at the sky, so privacy is often less of a problem than people expect; the exception is a low rooflight overlooked from a neighbour's higher window.
On a terrace in Romsey or off Mill Road, rear additions sit close together and a neighbour's loft window can look down onto your rear slope. If that sightline exists, you have three routes:
- obscure or satin glass, which some makers offer for conservation units and others do not, so it has to be confirmed for the size and range chosen;
- a blind fitted to the inside of the frame, again depending on what the range supports;
- moving the rooflight higher up the slope, where the angle takes it out of view.
Clear glass keeps the view of the sky, which is much of the pleasure of a bathroom rooflight. Overhead glazing should have a laminated inner pane under Part K so that broken glass stays in place, a point that matters more over a bath. If the slope faces south, solar control glass can take the edge off summer heat; see can conservation rooflights have solar control glass.
Where to put it in the room
Position decides whether the rooflight lights the mirror or just the ceiling, and whether you can reach the handle.
| Position | Light | Watch for |
|---|---|---|
| Over the bath | Sky view while bathing | Reach, safety glass |
| Over the shower | Bright enclosure | Direct spray on frame |
| Near the basin | Even light on the face | Glare on the mirror |
| Near the door | General light | Easiest to open |
Orientation shapes the kind of light you get. A north slope gives soft, even light that is kind to a mirror at any hour. An east slope brings low morning sun straight into the room while you get ready; a west slope does the same for an evening bath. A south slope gives the most sun and the most heat, which suits a cold bathroom in winter and needs thought in July. We draw the sun path for your slope as part of the light plan so you can see where the bright spot will fall before the roof is opened. Avoid placing the frame directly in the line of a shower head: the glass is built for rain, but constant spray and soap film make the internal seals and finish work harder.
Questions people also ask
Can I put a conservation rooflight directly above a shower?
It can be done, and it gives a lovely bright enclosure, but it is better placed just to the side of the shower head so the frame is not in the direct spray, with the extract fan close by to take the steam.
Is obscure glass available in conservation rooflights?
It depends on the maker and the size. Some conservation ranges list an obscure or satin option and some do not, so we confirm it against the specification before it goes on your quote.
Does a bathroom rooflight need Building Regulations approval?
A new rooflight normally does, because it alters the roof structure and the thermal envelope. Where the work is notifiable we handle the Building Control notification, and the rooflight is fitted to current Building Regulations.
Will a conservation rooflight make my bathroom colder?
A modern double glazed unit loses more heat than an insulated roof, but far less than the old single glazed lights it often replaces, and on east, south and west slopes winter sun offsets some of that loss. Book a light survey and we will check it for your slope.
