Two roof windows side by side can give a loft far more light, and it is often possible. The answer depends on the rafters, the roof covering and how the pair is flashed together.
In older terraces and converted buildings in Old Market, a loft room can feel dim with a single small window, and fitting a pair is a common answer. It is more involved than doing one twice, because the structure and the weatherproofing both have to be handled together.
Why the rafters decide it
Each opening interrupts the roof timbers. For two windows side by side, rafters may need trimming and doubling up around the opening so the roof stays strong. The spacing of the existing rafters often influences which size and arrangement works best, so we measure inside the loft before promising a layout.
Where the loft was converted at some point, there may already be extra timbers or alterations that change what is possible. We trace those before settling on a layout, so that nothing is cut that is carrying more load than it appears to.
A combined flashing, not two single ones
Windows set next to each other need a flashing kit made for the pairing, matched to the roof covering. Two ordinary flashings jammed together would leave a weak joint between them. VELUX and similar roof windows come with kits for slate, plain tile and profiled coverings, so the right one is chosen for your roof.
Matching the kit to the covering is not optional. The wrong kit leaves gaps that water will find in the first hard storm, however neatly the window itself is fitted, so we confirm the covering type on site before ordering anything.
Light, headroom and the room inside
A pair lets in more daylight but also changes how the room feels. We think about where people will stand, where furniture goes and how the openings line up with the floor. The lining, insulation and vapour control around the openings are done carefully so the room stays warm and condensation is kept in check.
Older buildings and their quirks
Roofs on older central buildings are rarely uniform. Timbers may be uneven, the covering may be mixed, and access is often limited. We look closely before agreeing the arrangement, and where the roof needs strengthening we say so. The work may need planning or Building Regulations checks, and we advise before work starts.
- Rafter spacing and the condition of the timbers.
- The roof covering and the matching flashing kit.
- Room layout, headroom and furniture positions.
- How scaffolding and deliveries will fit the street.
What to expect on the day
Fitting a pair is a larger job than a single window, but it is planned and tidy. We protect the room below, open the roof only as far as needed, and aim to leave it weathertight at the end of each day. You are told in advance what will happen and when, so the room is cleared and ready.
Frequently Asked Questions
Can any two windows be placed together?
Not automatically. They need to suit the rafter spacing and the roof covering, and the flashing kit has to be designed for the pairing. We check the loft and roof before agreeing the arrangement.
Will two windows leak more than one?
Not if they are fitted with the correct combined flashing kit and sealed carefully. Leaks usually come from poor flashing or sealing, so the detailing around and between the windows is where we take the most care.
Does a pair affect the roof structure?
Yes, because the rafters are interrupted. They are usually trimmed and doubled up around the openings to keep the roof strong. We look at the timbers in the loft and explain what is needed before we start.
Talk to our team about VELUX and roof window installation in Old Market
Every roof is different — the fastest way to get an accurate answer is a quick chat with our team.