Can a Roof Window Be Added to an Existing Tiled Roof in Montpelier?

Yes, in most cases a roof window can be cut into an existing tiled roof. What decides it is the structure behind the covering. Here is how it goes on Montpelier's Victorian roofs and loft rooms.

A new roof window means opening up a working roof, so it needs planning from the inside out. The rafters, the roof covering, the lining and the finished room all have to work together. On Montpelier's tall Victorian houses and flats, that often means a loft room that is being brought into use for the first time.

What decides whether it works

We look at the roof pitch, the rafter size and spacing, the covering and what sits below in the loft. Window and roof must suit each other, and the opening has to be where there is enough headroom to make it worthwhile. Chimney breasts, party walls and existing purlins can all limit where the window can go, so the position is chosen on site.

Sloping ceilings and the stair position below also matter, since the window should light the part of the room people actually use and give a safe route out. We usually mark the proposed position inside the room first, so you can see what you would get.

Cutting into the roof

A section of tiles and battens is removed and rafters are trimmed and doubled up around the opening so the structure stays sound. Timber is cut square, a new frame fixed, and the window is set into it. This is the part where the roof is open to weather, so we plan it around the forecast and keep the opening covered whenever work stops.

• Tiles and battens lifted back from the opening
• Rafters trimmed and doubled up
• Frame fixed square to the structure
• Roof covered overnight if work is not finished

Flashing that matches the covering

VELUX and similar roof windows are supplied with a flashing kit chosen to suit the roof covering, whether plain tiles, slate or interlocking tiles. The kit lets water run round the window and back onto the roof. A mismatched kit is a common cause of leaks later, so we confirm the covering type before ordering anything.

Plain tile, slate and interlocking coverings each need a different kit, and a replacement kit cannot simply be swapped across between them without checking. If the covering is old or brittle, we say so before cutting, because disturbing tired tiles around a new opening can cause more damage than the window itself.

Lining, insulation and the inside

Inside, the opening is lined and insulated, and a vapour control layer is fitted so warm damp air does not reach cold timber. Neat plastered or boarded splays bring daylight into the room and finish the opening. In a flat or loft conversion, the window position also needs to line up with floor level and any sloping ceilings. Roof windows may need planning or Building Regulations checks, and we advise before work starts.

Access, scaffold and living with the work

On steep Montpelier streets with tight access, scaffold or a protected working platform is needed, and we plan deliveries and waste removal in advance. We tell you which rooms will be affected, how long the roof stays open on the day and what is left to finish indoors. After fitting, we show you how to open and clean the window.

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