What Is a Roof Balcony Window?

A standard roof window opens like a hinged hatch and gives you light and ventilation but no place to stand. A balcony-style window is built to open further. The top section swings upwards and out, while the lower part folds down and forward, turning the window into a small railed platform at roof level. You then stand inside the room with your head and shoulders in the open air, rather than leaning out of a gap.

This is a roof window, not a true balcony. There is no floor sticking out over the garden. The lower section forms a guard at about waist height, and the floor you stand on is still the loft floor. For that reason it suits a loft room that has no space for a dormer, a Juliet balcony or an outside terrace, and where you want a view without altering the shape of the roof.

Different makers build these in their own ways, so read the model's data sheet for how the sash moves and how the guard is made. Because the window folds out, the sash and its hinges carry more load than on a standard unit, and they are made accordingly.

These windows are tall. The frame has to stretch from just above floor level up to a comfortable head height, so the opening is much bigger than a standard roof window. That has the same consequences we describe in our answer on replacing a Velux with a bigger one: rafters cut, trimmers fitted, and a doubled timber carrying the cut ends.

Pitch matters because the design only works within a stated range. The data sheet for the exact model gives the lowest and highest roof angle, and the position of the frame relative to the floor of the room. On a shallow roof the window may not open far enough to stand under; on a steep one the folded section sits at a different angle to the floor. Measure the pitch on site and check it against the sheet before ordering.

The room inside needs a floor-to-window relationship that works, too. If the roof meets the wall too low, there will not be enough height. We check this from the loft side with a tape and a level, and tell you what the window will and will not give you.

Permitted development for roofs sits in Class C of the General Permitted Development Order, and one of its tests is how far a roof alteration pokes out of the slope: 0.15 metres at most. A window that folds outwards when open raises an obvious question, so take the data sheet to the planning team at your council and ask whether they judge the closed position, the open position or both. A side-facing slope brings extra conditions on glazing and opening, set out in the same Class.

Flats are outside the dwellinghouse definition, so those rights do not apply to them. Listed buildings need listed building consent when the alteration touches their character, and an Article 4 direction, which some conservation areas carry, can change things again, so check your own address.

Building control is separate. The Planning Portal counts roof windows as part of the building envelope, and Crawley Building Control puts new window openings in roofs on its approval list. A loft room for sleeping may also need an escape window under Approved Document B, with an openable area of at least 0.33 square metres.

The appeal is clear: a view and fresh air in a loft room without building a dormer. The compromise is that you are looking out through a roof opening, not standing on a terrace. For many lofts that is enough, and it avoids the larger structural and planning questions a dormer raises.

What fixes the price here is the model, the size of the opening, the timber work, the covering cut around it and the access needed, so the written quote follows the survey. As a yardstick for a plain window only, Checkatrade's October 2026 table puts a new roof window at £1,250 on average across the UK, and a folding design with its larger opening will cost more than that.

A balcony window also needs a safe way to use it. Think about children and pets near an open guard, the strength of the catches and how the window closes against a gust. Ask the supplier how the lower section locks, and how the sash is held in a wind.

Our roof windows and skylights page sets out the range of work, and fire escape roof windows in a loft covers the escape rules.