The skylight opens properly and the glass looks clear. It is on the replacement list anyway, because the roof is being redone.
Dave asks the owner to put two questions beside it: "What is wrong with this one?" and "What would we disturb if we came back later?"
Both deserve answers. Reroofing is a convenient time to assess a skylight and its flashing, not an automatic instruction to discard it. A sound compatible unit can be worth keeping. Failed glazing, a deteriorated frame or a roof connection that cannot be rebuilt properly changes the choice.
Assess More Than the Glass
Check the glazing for internal fogging, the frame for deterioration and operating components for problems. A curb-mounted unit also needs a sound, correctly sized curb. The roof connection must suit the new covering and assembly height.
Ask whether the existing model has available service parts and an appropriate flashing arrangement. A unit that appears sound indoors may still be difficult to integrate reliably with the proposed roof work.
VELUX's replacement information provides symptoms to consider, while its installation resources help establish the suitable mounting and flashing requirements for a selected model.
Before comparing a service part with a new unit, identify the existing skylight from its product record.
Flashing is woven into the surrounding roof
The side pieces meet successive shingle courses. Replacing the unit during reroofing gives access to those relationships, which are harder to inspect when the covering stays in place.
Schematic view. Shows relationships, not installation dimensions.
Include the Four-Sided Roof Connection
Water arriving above a skylight must pass around it and return to the roof below. In a suitable shingle installation, head flashing handles the uphill side, step flashing works with the side courses and the lower apron discharges onto the downslope roofing. VELUX's flashing systems are selected for the skylight, covering and roof slope; a generic promise to seal around the frame does not name that connection.
Have the exposed decking and curb assessed when the roofing comes off. A unit can look ordinary from outside while the backing needs repair. Request photographs and a change-approval process before that discovery changes the price. Do not turn a hidden-damage possibility into an automatic replacement recommendation.
Room-side condensation needs a separate diagnosis from rain entering the roof junction. Record whether moisture appears on cold glass or after rain around the frame, then have the route confirmed before expanding the scope. Read the skylight condensation guide if the symptom is mainly indoors during cold weather.
Retain and Reflash Versus Replace
A fair comparison gives both options a sound roof connection. "Replace the skylight properly" versus "leave everything untouched" is not an equal choice.
For retention, include the flashing work needed to integrate the existing unit with the new roof. For replacement, include any curb or opening changes and the interior consequences: insulation, trim, drywall, blinds and controls where relevant.
A unit that fits the old opening can keep interior work modest. A different size may change the project considerably. That is why a low product price can still lead to a larger completed bill.
Before deciding an older unit must go, identify its service needs and available parts alongside the condition of the flashing and frame.
Consider the Cost of Coming Back
The quote now separates the unit from access and flashing work. That makes "we are already here" a useful cost consideration rather than a diagnosis. The owner can compare a sound retained installation with a complete replacement, including the trim and blinds everyone was about to forget.
Replacing a skylight after reroofing can require lifting relatively new shingles or disturbing membrane details. Access and setup may be paid for twice. There is also the inconvenience of another work period.
Those are legitimate reasons to replace a unit with uncertain remaining serviceability during the roof project. They are weaker reasons to discard a recent, sound unit that can be integrated according to its instructions.
Ask the contractor to explain the specific finding behind the recommendation. Age is context. A cracked frame, failed glazing or unavailable flashing is a more concrete reason.
A Useful Decision in Three Cases
- Recent, sound and compatible: retaining it with the required roof-detail work may avoid needless replacement.
- Fogged glazing or troublesome operation: compare available service parts with complete replacement while access is convenient.
- Deteriorated frame, curb or unsuitable flashing arrangement: address that condition with the roof work rather than leave a likely return visit built into the new installation.
Keep product coverage separate from installer workmanship; the warranty guide explains why. The practical goal is justified work at a sensible time, with the roof connection and room finish both accounted for.
Giving up the opening is another option, but skylight removal must include the roof, insulation and room finish.