Skylights and rooflights in Brynmawr

Count the windows and doors in your house before you add another. Approved Document L (Wales) is the energy guidance for homes, and when a window or door opening is enlarged or a new one is created, it says the total area of windows and doors should not exceed 25% of the home's total floor area. Guidance of this kind is written as "should", and it explains why a survey begins with what the house already has.

The wording is changing. From 4 March 2027 a newer Welsh edition of the document takes effect. Approved Document L (Wales) in that edition names roof windows and rooflights in the total as well as windows and doors, and it allows more than 25% where the home's energy efficiency is improved to compensate. A plan made now for glass in a roof deserves a look at both editions, to see which applies to the project.

Light needs differ by room. A kitchen, a study and a child's bedroom ask for brighter daylight than a landing or a utility cupboard. The point holds for a kitchen with a lantern as much as for a loft with two roof windows. The figures needed are the floor area and the existing openings, both easy to gather with a tape measure and an afternoon in the house.

Separate figures cover how well each fitting keeps heat in. A new or replacement roof window in an existing home should be no worse than 1.4 W/m²K, or Window Energy Rating band B, in the current edition. A rooflight should be no worse than 2.2 W/m²K. The two numbers belong to two different kinds of fitting, so the quote should say which is which.

Do some of the thinking beforehand. Walk through the house on a dull afternoon and note, room by room, where light is short and where it is plentiful. Mark the dark corners on a floor plan if you have one, even a rough sketch, and bring it. The energy-efficient rooflights hub covers the rest of the topic.

Brynmawr stands between 380 and 460 m above sea level, and wherever a house sits, the glass in its roof is among the coldest surfaces in the building once the heating has gone off. Warm, damp air meets cold glass, and moisture settles on the pane. A bathroom can do it fastest, and a bedroom in a loft can do it overnight.

The remedies are plain ones: a sash you can open, an extractor fan that carries on after a shower, and vents wherever the old window had them. Approved Document F (Wales) deals with an old window that had trickle vents, and says the window going in should carry vents at least as large, controlled by the occupant or working automatically.

Look at the glass from the bed. After dark a roof window shows little of its own: switch the room light on and the pane returns the room, switch the bedside lamp off and it fades to a dark square. That is when moisture matters, because nobody is awake to wipe it, and the pane can drip to the sill by morning if the air is heavy.

For a loft bedroom, think about the blind as seriously as the glass. A blackout blind keeps the room dark when it is light early in summer, and it is worth choosing one that can be reached from the bed or from a landing near the stairs. Tell us who sleeps there, what time they wake, and whether anyone shares the room. A child's room and a spare room ask for different blinds, and the reach of a cord or a handle matters more with small arms.

Ask about the glazing. A roof window should meet 1.4 W/m²K or WER band B under the guidance, and the glazing is worth a question to any supplier. The double or triple glazing page compares the choices without prices.

Tell us which room the window is in, and whether the room is aired by day. Those two details settle more about condensation than the choice of frame does. A room where washing is dried indoors needs more air than one that is only slept in, and the survey notes which you have. If the window will sit over a bed, say which side, since it affects where a cord or a handle can be reached.