In the vast majority of cases, a leaking skylight is not a glazing problem — it's a flashing problem. The flashing is the lead or code metal that seals the junction between the skylight frame and the surrounding roof covering. When it fails, water enters at the frame edge and tracks behind the ceiling lining before emerging at the visible drip point below — which is almost never directly beneath the actual failure.
This distinction matters for cost. A homeowner who assumes the glass unit has failed is at risk of being quoted for a full unit replacement when what's needed is a flashing repair. A homeowner who has had sealant applied and reapplied without the leak stopping is almost certainly dealing with a flashing failure that no amount of surface sealant will fix.
There are two types of flashing on Dublin skylights — purpose-made manufacturer kits (Velux, Fakro, RoofLITE) matched to the specific roof covering type, and site-formed lead flashing dressed on site by the roofer. Both perform well when done correctly. Site-formed lead is also where a lot of Dublin skylight installations fail — lead that hasn't been dressed properly, isn't lapped sufficiently, or has been fixed in a way that doesn't allow for thermal movement.
Sean inspects the full flashing detail on every skylight job — not just the visible sealant bead — before recommending any repair. In most cases the unit itself is sound and the fix is at the flashing level.
No jargon. No hard sell. Just a clear process from your first call to a weatherproof roof.
The most common skylight repair we carry out across Dublin. Failed lead flashing or deteriorated manufacturer flashing kits are replaced correctly — using the right flashing type for the roof covering profile and dressing the lead properly to allow for thermal movement. Where a previous flashing installation was incorrectly done, we correct the detail rather than simply patching over it.
Where the perimeter seal between the skylight frame and the surrounding roof covering has failed but the flashing itself is sound, resealing with the correct product — matched to the frame material and roof covering type — is the appropriate repair. We also replace worn weatherstrips and gaskets around the opening sash where draught ingress is the presenting problem.
Where the sealed glazing unit has failed — visible as persistent misting between the panes — the glass unit is replaced without disturbing the frame. This restores thermal performance and eliminates the condensation cavity at a fraction of the cost of full unit replacement.
Velux roof windows use a range of opening mechanisms — manual centre-pivot, top-hung, electrically operated — that develop specific failure modes over time. Handles, hinges, pivot brackets, and operating rods can all be repaired or replaced to restore smooth, secure operation without replacing the full unit.
Where internal Velux blinds — blackout, pleated, or roller — have failed or need upgrading, we supply and fit genuine Velux accessories matched to the window series and size.
Where a skylight frame has deteriorated, the unit is no longer thermally efficient, the glass is cracked or broken, or the window is simply beyond economic repair, we carry out full unit replacement. We supply and fit Velux, Fakro, and RoofLITE units in the correct size for the existing opening, with new manufacturer flashing kit matched to the roof covering type.
Where a homeowner wants to add a skylight to an existing roof — to bring natural light into an attic conversion, a landing, or a dark bedroom — we carry out the full installation including cutting the roof opening, installing the structural trimmers, laying the unit, and flashing correctly to the surrounding roof. All new installations include an inspection of the roof structure in the opening area before the unit goes in.
Rooflights set into flat roofs — square or rectangular units sitting on an upstand rather than set into the pitch — are a separate category with different flashing requirements. We repair and reseal flat roof rooflights as part of our flat roofing service, addressing the junction between the rooflight kerb and the flat roof membrane correctly.
A cracked or broken skylight is an immediate water ingress point that needs temporary weatherproofing and a prompt permanent repair. We respond to emergency skylight calls across Dublin City and County — making the opening weathertight quickly and scheduling the permanent fix.
Real Results From Home-Owners in Dublin!
Velux is the dominant brand in the Irish roof window market and the unit found on the overwhelming majority of Dublin homes with skylights. They're well-engineered, long-lasting products — a correctly installed and maintained Velux window will perform well for 20 to 30 years. Here's what we typically encounter on Dublin properties at different stages of a Velux window's life.
Newer installations (under 10 years) Leaks on relatively new Velux windows are almost always installation-related — flashing that wasn't fitted correctly, a felt collar that wasn't properly dressed around the frame, or a sealant application instead of the correct flashing kit. These repairs are straightforward when diagnosed correctly.
Mid-life units (10–20 years) The most common issues in this age range are weatherstrip and gasket deterioration leading to draught ingress, and glazing unit seal failure causing misting between the panes. Both are repairable without unit replacement. Flashing condition should be checked at this stage — original lead work on mid-life installations can start to show signs of fatigue cracking and may need re-dressing.
Older units (20+ years) Velux windows from the 1990s and early 2000s are still in service on a large proportion of Dublin's attic conversions and dormer extensions. By this age, the glazing unit is typically underperforming thermally regardless of whether the seal has visibly failed. Opening mechanisms on manual units may be worn. Flashing in this age range is frequently at or past end of life. Full unit replacement becomes the more cost-effective option over ongoing repairs at this stage — and modern Velux units are substantially more thermally efficient than the units being replaced, with an immediate impact on heating costs.
DJ Roofing Dublin carries out skylight repairs and installations throughout Dublin City and County — every area, north to south.
North Dublin: Swords, Malahide, Howth, Clontarf, Drumcondra, Glasnevin, Finglas, Blanchardstown, Castleknock, Santry, Raheny, Artane, Baldoyle
South Dublin: Rathfarnham, Terenure, Templeogue, Dundrum, Stillorgan, Blackrock, Dún Laoghaire, Dalkey, Killiney, Churchtown, Rathmines, Ranelagh, Sandymount
West Dublin: Lucan, Clondalkin, Tallaght, Palmerstown, Rathcoole, Newcastle, Saggart, Adamstown
Dublin City Centre: D1, D2, D4, D6, D7, D8, D12
Not sure if we cover your area? Call us — we almost certainly do.
Because sealant applied over a failed flashing detail doesn't fix the flashing — it temporarily slows the water entry until the sealant deteriorates or the movement of the roof reopens the gap. If your skylight has been resealed more than once and is still leaking, the flashing needs to be properly inspected and most likely replaced. Surface sealant is not a substitute for correctly installed flashing.
The key distinction is when the water appears. Condensation runs down the inside face of the glass in cold weather when the room below is warm and humid — kitchen, bathroom, or a bedroom with poor ventilation. A genuine leak appears during or after rainfall, regardless of internal conditions. If you're not sure, call us — we diagnose this at the inspection stage before recommending any repair.
Yes, in most cases. If the frame is sound and the issue is a failed sealed unit — persistent misting between the panes — the glazing unit is replaced without disturbing the frame or the flashing. This is considerably less expensive than full unit replacement.
Most standard repairs — flashing, resealing, glazing unit — are completed within a few hours. Full unit replacement takes longer, depending on the roof covering type and access. We'll give you a realistic timeframe in the written quote.
It depends on the specific condition of the unit, but at 20-plus years we would typically assess the glazing performance, the frame condition, and the flashing status at the inspection stage and give you a straight cost comparison between repair and replacement. Modern Velux units are substantially more thermally efficient than units from the 1990s and early 2000s — in some cases replacement pays for itself over a few years in reduced heat loss.
Yes. We carry out new skylight installations — including cutting the roof opening, structural trimming, unit installation, and flashing — across Dublin City and County. Contact us for a free survey and quote.
A straightforward resealing job is minor. Flashing replacement is more involved. Full unit replacement depends on the size and type of the window. We always inspect first and provide a written quote — so you have an exact price before committing to anything.
If your skylight is leaking, draughty, misting up, or simply hasn't been looked at in years — a proper inspection is the right starting point. Most skylight problems are significantly more affordable to fix than homeowners expect, particularly when caught before water has been in the structure for a season.
Call DJ Roofing Dublin for a free skylight inspection across Dublin City and County. Honest diagnosis, written quote, no call-out fee, no pressure.
DJ Roofing offers a full range of roofing services for homeowners and landlords throughout Dublin.
DJ Roofing Dublin provides professional roofing services to homeowners and commercial property owners throughout Dublin City and County. Our services include roof repairs, roof replacement, flat roof repairs, chimney repairs, slate roof repairs, fascia and soffit replacement, gutter repairs, skylight repairs, and emergency roofing.
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