Skylight Repairs Across South London
Leaking or failed skylights, Velux windows, and roof lanterns repaired properly — stopping water at the roofline junction, not just smearing silicone around the glass.
Most Skylight Leaks Aren't the Skylight
When water drips from a roof window during rainfall, the automatic assumption is that the glass has failed or a rubber window gasket has perished. In practice, the vast majority of skylight leaks stem from the flashing kit, upstand detailing, or surrounding tile junctions, not the glazing unit.
Where any roof window cuts through a pitched roof or flat extension, a specialised perimeter flashing system bridges the gap between the window frame and the surrounding covering (whether slate, clay tile, or flat roof membrane).
If this flashing:
Was poorly installed or cut short during a loft conversion,
Has become choked with moss, pine needles, and rooftop silt, or
Has split due to thermal expansion,
rainwater backs up behind the frame, overflows the drainage channels, and tracks down the internal timber reveal.
This is where calling a specialist roofer makes the difference. A glazier or window fitter looks almost exclusively at the sash, the latch, and the glass pane. A roofing specialist inspects the entire weatherproofing detail: how the water sheds from the tiles above, how the side soakers channel rainfall, and whether the bottom apron is properly dressed over the roof covering below.
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Real feedback from real jobs — roof repairs, replacements and flat roofing across London.
Repair or Replace Your Velux Skylight?
Repair is the right call when the leak traces back to a split lead apron, a blocked perimeter drainage channel, degraded perimeter foam gaskets, or cracked surrounding tiles, while the timber or polyurethane window frame and glazing remain structurally sound.
Replacement is the better long-term investment if the window is 20+ years old, has broken internal mechanical hinges, suffers from rotted internal timber frames, or exhibits "blown" double glazing (permanent fogging or moisture trapped between the two glass panes). Replacing an obsolete, failing rooflight during scheduled roof maintenance is far more cost-effective than continuous short-term call-outs.

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Common Skylight & Roof Lantern Problems in Our Area
Debris Blockages Around Loft Conversions (Dulwich, Beckenham, Chislehurst):
Properties situated on tree-lined residential avenues suffer from heavy leaf fall and moss build-up. Foliage collects in the hidden collection channels beneath the top and side flashing covers of Velux windows, forcing heavy downpours to breach the side gutters and enter the ceiling rafters.
Perished Upstands on Kitchen Extensions (Bromley, Orpington, Croydon):
South London homes frequently feature large flat-roof extensions illuminated by contemporary flat glass rooflights or aluminium roof lanterns. If the flat roof membrane (felt, EPDM, or GRP) was not dressed high enough up the timber upstand kerb, driving rain hits the joint and leaks directly down the plasterboard surround.
Incorrect Flashing Kits on Period Slate Roofs (Catford, Selhurst, Bexley):
Installing a roof window into a traditional natural slate roof requires dedicated recessed slate flashing kits with interlaced side soakers. When general builders use standard deep-profile tile kits on a flush slate roof, gaps are left exposed to wind-driven rain.
Wind-Driven Water Ingress on the North Downs (Warlingham, Selsdon, Sevenoaks):
Higher-altitude properties face intense driving winds. Weakened bottom aprons can lift in high gales, driving rainwater straight under the sill into the ceiling void.
Skylight Repair FAQ's
My skylight leaks, but the glass and frame look undamaged. What is causing it?
In nearly all cases, this is caused by a failure of the exterior flashing kit or a blockage in the perimeter drainage channels beneath the outer casing. Rainwater pools behind the frame, penetrates the batten line, and runs down the interior plasterboard reveal, making it look as though the window has failed.
Do you repair flat roof lanterns as well as pitched Velux windows?
Yes. We regularly repair leaks around aluminium and uPVC roof lanterns on rear kitchen extensions. Most leaks occur at the junction where the flat roof membrane wraps up the supporting timber kerb beneath the lantern overhang.
Can you replace just the flashing kit without buying a brand-new window?
Yes. If your window frame and glass unit are in good working order, we can replace the external aluminium flashing kit, foam gaskets, and bottom apron with a matching manufacturer replacement kit without removing the internal window frame.
Will repairing my skylight require expensive scaffolding?
Generally no. Most roof window repairs and replacements on standard two-storey properties can be accessed and completed safely from roof ladders or internal access, keeping costs and turnaround times down. Scaffolding is only required if the roof pitch is unusually steep or access is obstructed.
Why is there condensation forming inside the double-glazed panes?
If moisture, fogging, or droplet staining is trapped between the two panes of glass, the hermetic factory seal around the glazing unit has broken. We can measure and replace the individual double-glazed pane without having to tear out the entire window frame.
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Areas We Cover Near You
Safeguard Roofing provides skylight repairs, flashing renewals, and roof window servicing across South London, Bromley Borough, Croydon, and the North Kent/Surrey borders:
Bromley Borough: Bromley, Beckenham, Orpington, Chislehurst
Croydon & Surrey Borders: Croydon, Purley, Selsdon, Selhurst, Warlingham
South East London & Bexley: Dulwich, Catford, Eltham, Sidcup, Bexley
Kent Borders: Swanley, Sevenoaks
Additional Roofing Services in South London
If you have any leaky roof problems that have to be fixed fast or a leak in your gutter, we are the local roofing company for you!
Get Your Skylight Repaired Properly
A leaking skylight left unattended rots timber rafters, stains ceiling plasterboard, and ruins insulation. Treating just the glass won’t fix the leak if the flashing or roof interface is compromised.
Call Harvey directly to discuss what you're seeing. He will inspect the window and its surrounding roof detailing in person and provide an honest, fixed written quote.