VELUX Window Installers › St Mellons › Guide
Fitting a VELUX or similar roof window looks simple from the room below, but it cuts into the roof structure and the weatherproofing. Getting it right comes down to checks made beforehand. Here are the ones we make on lofts and roofs across St Mellons, before we price or book the work.
The roof covering and flashing kit
Every window needs a flashing kit matched to the roof covering. Most St Mellons homes have concrete interlocking tile, and the kit must suit that profile. A mismatch is the usual source of leaks around a roof window, so we identify the tile first and choose the kit to suit it.
The rafters and the opening
The window sits in an opening in the roof, and that usually means trimming one or more rafters and doubling up the timbers around it. Whether that is possible depends on the roof design. Homes with trussed rafters, common on later estates in Pontprennau and Castleton, need particular care, and we check this on site.
- Rafter spacing and size at the chosen position
- Whether trusses or purlins are in the way
- Condition of the timber around the opening
- Position relative to chimneys, valleys and ridges
Headroom and the room below
A window is no use if you cannot stand or see out of it. We look at head height, floor position and where the window will sit relative to a bed, desk or stair. The best position is often not the one first imagined, so we talk through it with you from inside the loft.
It also pays to think about how the window will be used. A roof window that opens for cleaning and ventilation needs clear space around it inside, and a position that suits you standing, so we talk through reach and use before settling on a spot.
Lining, insulation and condensation
The opening needs a lining, insulation and a vapour control layer to stop warm air getting into the cold roof space and condensing. Condensation is often mistaken for a leak. We check the insulation and ventilation of the roof around the window so the room stays dry in damp east Cardiff weather.
- Insulation fitted tight round the window frame
- Vapour control layer sealed to the lining
- Roof ventilation not blocked by the new opening
Permission and who to ask
A roof window may need planning or Building Regulations checks, and we advise before work starts. Ask any fitter how they match the flashing to your tile, how they handle the rafters and who is responsible for the lining. Please do not go onto the roof to look yourself. Call us for a proper look.
Need velux window installers in St Mellons? See our velux window installers in St Mellons page, or call 07766 547309.
More Guides for St Mellons
Common Questions
Can I choose any size of window?
Not always. The size depends on rafter spacing, the roof structure and where the opening can safely go. We check on site, then suggest sizes and positions that suit both the roof and the room below.
Why do some roof windows leak after fitting?
Usually the flashing, the sealing or the roof covering around the window, not the glass. A kit that does not match the tile, or poor sealing at the corners, is a common cause. A proper match and careful fitting prevent it.
Is condensation the same as a leak?
No. Condensation forms when warm damp air meets a cold surface and looks like a leak. A well insulated, sealed lining and good ventilation reduce it. We check the details around the window to tell the two apart.
Get a Quote in St Mellons
Tell us what the roof is doing in St Mellons and we will look at it. Call 07766 547309, message us on WhatsApp or use the form below.