Field guide
Roofer Skylight Replacement Pages That Blame the Flashing Correctly
Owners shop for skylights by looking up. Roofers diagnose them by looking at the roof around them, because that is where the water gets in.
A stain under a skylight starts an argument between the glass, the flashing, and the seal. The page that separates the three, with ages attached, ends the argument and sells the right job.
Three failures, three different fixes
Condensation or fog between panes means the sealed unit has failed. The glass is done, the roof may be fine, and the fix is a new unit or glazing, not flashing work. A drip that tracks one side in wind driven rain points at flashing or the step flashing where the skylight meets the shingles. Water at the drywall corners can also be interior condensation running off a cold frame in winter, which is a humidity problem wearing a leak costume.
Naming all three saves owners the most common bad purchase in this category: a new skylight installed to fix a flashing leak, or flashing work sold to cure a dead sealed unit.
Deck mount versus curb mount changes the quote
Deck mounted units sit low, with the frame fastened to the roof deck and flashing woven into the shingle courses. Curb mounted units sit on a raised curb, common on lower slopes and commercial style roofs, and the cap can sometimes be replaced while the curb and flashing stay.
The page should ask which type and what slope, because flashing kits are model and mount specific, and a generic kit forced onto the wrong unit is next winter leak. Photographs of the data plate, often on the frame edge, settle the model question in one text message.
Replace with the roof, and say why in dollars
When a roof is being replaced, the flashing around a skylight is torn out and rebuilt anyway. Adding a skylight swap to that job costs the unit and a fraction of the labor. Doing it two years later means paying to open a sound roof, disturb new shingles, and rebuild flashing that was new the year before last.
So the honest page puts an age rule in print: if the skylight is close to the age of the old roof, replace it with the roof. Owners respect a roofer who talks them out of a standalone job and into the cheaper sequence.
Caulk is not a skylight repair
Exterior sealant smeared around a skylight frame is the tell of a job that will be redone. It traps water as often as it sheds it, voids the clean flashing lines the unit depends on, and has to be scraped off by whoever does the real repair. A page should say it does not offer caulking as a fix, and will inspect and quote the flashing or the unit instead.
End on the check owners can do from inside: look for fogging between panes, peeling paint on the shaft, and stains that appear with wind direction, and note which. That note turns the first visit into a diagnosis instead of a shrug.
Related reading
Related reading: Roofer Soffit and Fascia Pages That Connect Rot to the Gutter Line, Roofer Moss and Algae Pages That Treat the Roof, Not Just the Stain, and Roofer Skylight Pages That Separate Condensation From a Real Leak.
Frequently asked questions
Why is my skylight leaking?
Most often the flashing where the skylight meets the roof has failed, or the unit seals have aged out. Fog between panes is a failed sealed unit, a different problem. Stains can also come from indoor condensation on a cold frame. Each cause has a different fix, which is why inspection comes before quoting.
Should I replace my skylight when I replace the roof?
Usually yes if the skylight is anywhere near the age of the roof. Flashing is rebuilt during a re roof anyway, so swapping the unit then costs far less than opening a new roof later to do the same flashing work again.
What is the difference between deck mounted and curb mounted skylights?
Deck mounted skylights fasten directly to the roof deck and sit low, with flashing integrated into the shingles. Curb mounted units sit on a raised frame or curb, common on low slopes, and sometimes only the cap needs replacing. The mount type decides the unit and flashing kit.
Can a leaking skylight just be resealed?
Surface caulking is rarely a real repair and often traps water against the frame. Lasting fixes address the flashing system or replace an aged out unit. A roofer who offers sealant as the solution is usually deferring the leak, not fixing it.