Answer · Roof windows
Are Roof Windows a Good Idea?
The short answer
Yes, a roof window is a good idea in most rooms with a sloping roof, when it is fitted properly and sized for the spot below it. It brings daylight into a loft, landing or bathroom that has no good wall for a window, and it gives you ventilation as well. The cons are real but manageable. Glare and summer heat need glass and blinds chosen for the slope, and a poor flashing detail can leak. Those are matters of fitting and choice, not reasons to avoid the idea. See the full range on our roof windows page.
Usually yes, if the window is put where the light is needed.
What roof windows do well
A window in a roof lets in more daylight than the same window in a wall, because it looks at open sky and not at a fence or a neighbour's brickwork. A loft room that was dim becomes a place where you can read, work or sleep without switching on a lamp. A landing or stairwell that was a dark tunnel becomes a place that does not need a light at noon.
That is the first and best reason. The second is air. A roof window opens, and warm air leaves through the top of the room while cooler air comes in lower down. A bathroom or a loft that has a stuffy feel can improve a great deal with one opening sash.
A way to use the roof space
Rooms in the roof need a window of some kind. A roof window is the plainest way to give one, and it does not need the structure of a dormer. If you are thinking about a conversion, our guide to roof windows for loft conversions deals with head height, escape and the regulations.
Putting light where you stand
This is the idea behind our work. People ask about a room, but they mean a place in it, such as the desk, the basin or the top stair. A roof window can be set so that the light reaches that place. A wall window on the far side of the room cannot.
What to weigh against them
Every product has a downside, and the sensible thing is to know where it is.
Heat and glare
A south-facing roof window in summer can bring heat into the room. Glass with a solar control coating reduces it, and an external blind reduces it more than an internal one. A north-facing slope sends in steadier light with less heat. If a bedroom window will face south, plan the blind with the window.
Leaks and flashing
A roof window is a hole in the roof with a seal around it. The seal is a flashing kit, made for each type of covering, and its fitting is where leaks come from. A window fitted with the right flashing kit for slate, concrete tile or clay tile, and properly dressed, does not leak because it is a roof window. The risk is in the work, which is why the work is guaranteed. A written 10-year guarantee backs our workmanship.
Cold and condensation
A roof window loses heat faster than a solid roof does. Part L wants new and replacement roof windows at no more than 1.4 W/m²K, or alternatively a Window Energy Rating of B, and modern double and triple glazing manages it. Condensation at the frame is cut by a well-insulated surround and a window you open.
Cleaning and reach
A window high in a roof can be hard to reach. A centre-pivot sash turns so that you can clean the outer pane from inside, and a powered opener can be fitted where you cannot reach the handle. Our guide to centre-pivot or top-hung roof windows sets out how each type opens and which suits which spot.
Weighing a roof window up
In its favour
- Daylight from open sky
- Fresh air from an opening sash
- No wall needed
- Lights a place, not a wall
Watch for
- Summer heat on south slopes
- Flashing must match the covering
- Glare without a blind
- Reach to handle and glass
Who should think twice
A roof window does not suit every roof. A very shallow pitch limits some designs, and a roof that is too low in the room leaves the glass above the standing zone. Some roofs are covered in materials that need special flashing, and some properties are in a conservation area or are listed, where rules apply.
A house can normally take rooflights without a planning application, provided certain conditions are met, and our planning guide lists them. Flats and maisonettes sit outside those householder rights, so they need a separate check. Listed building consent is the route for most alterations to a listed house. In a conservation area the council may have withdrawn the usual freedoms by an Article 4 direction, so a call to the council comes first.
Building Regulations apply too. Cutting into the roof structure for a new window is building work, passed by the council or by a registered building control approver. A straight swap is controlled fitting and must meet the U-value. The notification is sent by us where it is required.
How to decide for your own roof
The best test is a survey where someone stands in the room with you. We ask where you will be when the window is used, mark that on a sketch, then measure the roof pitch, the rafter spacing and the covering. The survey is free, and the quote that follows is written and fixed for the whole job.
If a roof window is wrong for the spot, we will say so in the survey, and suggest another product such as a roof lantern, a sun tunnel or a flat rooflight. The right answer depends on the room. To start, send the free survey form, or WhatsApp 07880 284133 with a photo of the room.
Doubts before you decide
Do roof windows make a room too hot in summer?
They can on a south-facing slope. Solar control glass and an external blind cut the heat a good deal, and opening the sash lets warm air out at the top. A north-facing slope sends in less heat. We talk through the aspect at the survey and suggest glass to suit it.
Do roof windows leak?
A roof window fitted with the correct flashing kit for the roof covering, and dressed properly, is weathertight. Leaks come from poor flashing or damaged seals, not from the idea of a roof window. The fitting is covered by a written guarantee of 10 years.
Will a roof window add value to a house?
Value depends on the house, the street and the market, so any figure would be a guess. What is certain is that a bright, ventilated loft room or landing is more useful to live in, and that is the reason most people fit one.
What about a flat roof?
A roof window is designed for a slope. Over a flat roof, the right product is a flat rooflight or a lantern. Our flat roof rooflights page explains the options.
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Where do you want the light? Tell us in the form: the worktop, the stair, the desk.
No obligation. We survey before we price.
We cover Derby and 30 miles around.