Skylight Cost With a New Roof

Skylights arrived in Greater Victoria in two waves. The 1970s and 1980s put acrylic bubble domes on flat curbs into the low-pitched roofs of Gordon Head, Cordova Bay and Sidney ranchers, and most of those domes are now yellowed, crazed and sitting on curbs that have rotted from the inside. The 1990s and 2000s put glass deck-mounted units into the steep roofs of Langford, Colwood and Broadmead, and those are mostly sound but have reached the age where the factory flashing kit and the seals are due.

Shade is the local complication. A skylight under a Saanich or Highlands fir canopy collects needles and moss around the curb, and the debris dam is what causes most of the leaks blamed on the unit itself. Roofers here will often recommend a slightly smaller or curb-mounted replacement where a dome sat on a home-built curb, because the modern flashing kit is the fix, not the glass. On a heritage-designated home, confirm with the City of Victoria before enlarging or adding openings.

Every skylight is a hole in the roof with four sides of flashing. On a re-roof the crew must remove the old flashing, run ice-and-water membrane up the curb, and fit new step flashing on the sides, an apron below and a head flashing above, then weave it all into the new shingles. That is the $300 to $900 per unit in our model. Manufacturers sell flashing kits for deck-mounted units; curb-mounted domes get site-formed metal, which takes longer.

Ask how old the skylight is. If it went in with the last roof, it has 20 or more years of sun on the seals and glazing, and flashing it into a 25-year roof means opening the new roof in five years when it fogs or leaks. Replacing it now costs $1,500 to $3,000 in our model, but the flashing labour overlaps with the re-roof, so the effective premium over a re-flash is closer to $1,200 to $2,100. If the unit is under ten years old and the glass is clear and the seals intact, re-flash it.

• Replace: same age as the roof, fogged or yellowed glazing, acrylic dome, rotten curb
• Re-flash: under about 10 years, clear glass, factory flashing kit available
• Remove: unit no longer wanted, room has other light, roof over and add decking

A leaking skylight on a roof that is not being replaced is a repair menu item at $300 to $900 for re-flashing or resealing in our model. Most leaks are flashing or debris, not glass, and a reseal or re-flash resolves them. A rotten curb, condensation between panes or cracked acrylic means replacement, and on an old roof that is the moment to price the whole roof rather than pay twice for the flashing.

Ask the roofer to list each skylight with its treatment: re-flash, replace with a named unit and size, or remove. Ask whether the new unit is deck-mounted or curb-mounted and whether the manufacturer's flashing kit is included. Ask who does interior finishing if the opening size changes. Two quotes that differ by $3,000 on a three-skylight home often differ only in whether the skylights are being replaced.