Roof window installation in Birmingham

A new opening or a swap

A new opening means cutting the rafters, trimming the gap with extra timbers and framing a neat box for the window to sit in. The framing carries the load that the cut rafters used to carry, so the timber is sized for the span. Before we order the unit for anything bigger than a small window, the structural detail has to be in our hands.

A like-for-like swap is a gentler job. The old window comes out, the opening is checked for sound timber and the new window goes into the same hole. If the old unit was a different make, a new one in a similar size may fit with a few adjustments to the flashing.

Not every swap is simple. A window that has been in the roof for decades may have sat in an opening that does not quite match any current size, so the quote shows what, if anything, has to change in the framing. Both routes can appear on the same quote, with the new opening priced beside the swap, which shows the disruption each one brings as well as the money it costs.

Roof windows suit loft conversions, bungalows with rooms in the roof, dormer cheeks that have no wall window, landings and stairwells that sit under the slope, and extensions with a pitched roof. They are less of a fit on a flat roof, where a flat rooflight or a lantern is the usual answer. Our page on flat roof rooflights compares those.

Other ways to open

Some roof windows open wider than a standard sash, with a top-hung action and a lower panel that folds out to make a small balcony. A few makers also offer a hinged window that opens fully like a door, for rooms where the roof is steep enough to let you stand under it. These cost more and need careful detailing, so they appear on a quote only where the roof and the room suit them.

Electric windows open on a switch fixed to the wall, or with a handheld remote, and many close themselves when a rain sensor gets wet. They suit windows set out of reach, such as above a staircase. For the switches, remotes and motors the makers offer, see our electric and opening rooflights page, which sets them against each other.

Fixed windows have a place too. Over a stair landing, where nobody needs to look out, a fixed unit lights the space for less money and with no moving parts to look after. A fixed unit can sit above an opening one on a steep roof to bring light deep into a room.

Pine, white or something else

Clear lacquered pine gives a loft bedroom a warm, traditional look. Painted or white-finished frames sit more quietly against plaster and suit bathrooms and kitchens, where steam would test a bare timber face. Polyurethane-coated frames are built for those damp rooms and are wiped clean with a cloth.

Outside, the frame is covered in a metal cladding, commonly aluminium or zinc, in grey, black, brown or a few other shades. The cladding is what you see from the street and the garden, so it is worth choosing a colour that matches your tiles and your rainwater goods.

Where a house sits in a conservation area, a slimmer, flatter profile may suit the street better. Some makers produce a roof window that sits low to the roof surface, with a dark central glazing bar that echoes a traditional cast iron rooflight. Our page on conservation rooflights compares these for listed and conservation area homes. Ask at the survey if your street needs that kind of detail.

If your house already has a VELUX window, you are free to choose another make for the new ones, but the two may not sit in line with one another on the same slope. We look at that on site, and we may suggest matching the existing make to keep the roofline tidy. Our page on VELUX windows sets out what that range offers.

How we size and place them

1. 01

   Find the rafters

   We locate each rafter and the gap between them, because the width of the opening is set by the spacing of the timber.

2. 02

   Set the sill height

   The sill sits where you can reach the handle and see out. We mark it from inside with someone sitting and standing.

3. 03

   Check the view

   We stand in the room and look up through the planned position to check the sky, the trees and the neighbours.

4. 04

   Match to sizes

   Each maker has a size range, and we compare the opening to each one to see where the fit is neat.

5. 05

   Confirm before ordering

   We re-check the measurements on site, so the window arrives to fit.

When the roof is shallow

Every maker sets a lowest roof pitch for its windows, because a window in a shallow slope is more likely to let rain run back under the frame. Dormer roofs, porch roofs and the lower pitches of extensions often sit below that limit. Some makers offer a kit for low pitches, while others point you to a small lantern or a flat rooflight.

At the survey the pitch is measured, never judged by eye, and set against each maker's limit. Our answer on fitting a roof window in a low-pitch roof goes through the options for a shallow roof, and our page on flat roof rooflights covers the alternative.

Roof coverings can also hold surprises. Old slate roofs sometimes have brittle slates that crack when lifted, and we tell you if a few extra slates will need to be replaced to make the work good. That is entered as a separate line item on the quote.

Planning permission

Many roof windows sit within permitted development, and the rooflight planning guide lists what it requires. A rooflight on a listed building also needs listed building consent, however permitted development applies. Elsewhere, the right itself can be removed, whether through an Article 4 direction or through a planning condition.

In parts of Birmingham such as Moseley, Edgbaston and Harborne, some streets sit inside conservation areas. A window on a rear slope is often out of sight from the street, while one on the front slope is the one a council looks at hardest. Your address gets checked at the survey for its permission position, and we tell you what turns up. The council makes the decision.

The lining and the light well

A roof window sits in a splayed box of plasterboard that runs from the window frame to the ceiling and the wall. The lining, sometimes called the light well, is the part you see every day. The angle of the splay changes how the light moves into the room. A wide splay spreads it, and a narrow one makes a tunnel.

Insulation goes behind the lining so the cold from the roof does not reach the room. The gap between the window frame and the rafters is filled and sealed. A vapour control layer on the room side stops moist air from reaching the cold timber, which is the usual cause of damp marks around a badly lined window.

We agree the lining shape with you at the survey, and we bring the plastering into the quote where you want it, or leave it to your own plasterer with the details written down. Painting is yours to choose.

Replacing a tired window

Older roof windows in Birmingham are often timber, with sealed glass units that have misted, or with seals that have hardened and let in draughts. When the frame is in good order but the sealed glass unit has failed, a replacement glass unit can sometimes go in by itself. That is not notifiable, and it costs less. A whole new window is the better buy where the frame itself has failed.

How we tell a failed glass unit from a failed frame is covered on our misted and failed rooflight replacement page, and a quote can price both routes together. A replacement is also the moment to look at the glass and the blind, because a newer window keeps more heat in than one from a few decades ago.