Skylight Replacement in North New Jersey

The clearest sign is fog. If you see moisture, a milky haze, or condensation trapped between the panes, the insulated-glass seal has blown — the gas fill that insulated the unit has escaped and humid air has worked its way in — and that cannot be resealed from the roof. A double-pane skylight is a sealed assembly; once its edge seal fails, the fog is permanent and the unit has lost its insulating value. A fogged skylight is a replacement, full stop, and no amount of caulk or cleaning brings it back.

The second sign is the old plastic dome. Acrylic and polycarbonate domes last roughly 7 to 10 years before UV turns them yellow, hazy, and brittle; the ones still on many North Jersey roofs are 1980s- and 90s-vintage units that have gone brittle enough to crack at a touch. There's no polishing that back to clear. The third is simply age plus a leak: skylights do their best work for about 15 to 20 years, and once a unit past that starts leaking, the perimeter seals are wearing out all at once — reflashing just buys a season before you're back on the roof for the next failure.

How the new unit sits on the roof decides how it's flashed. A deck-mounted skylight sits low, right on the roof deck, sealed with a pre-attached deck seal and a manufacturer-matched flashing kit — the clean, low-profile standard for the asphalt-shingle roofs on most North Jersey houses. A curb-mounted skylight sits up on a site-built wooden curb wrapped in membrane and sealed with a gasket — the right answer on the low-slope and flat rear additions all over Bergen and Passaic, where raising the unit above the roof plane keeps water from ponding against it. A straight replacement usually matches the existing mount, but a re-roof is the moment to correct a unit that was wrong for its roof the first time.

Here's the part that separates a real replacement from a cheap reseal: the new skylight gets new flashing, every time. You cannot lap new shingles around old, in-place flashing and expect it to stay dry, and reusing corroded, face-nailed, or caulked-over flashing is the single most common reason a 'replaced' skylight leaks within a year. We set the new unit with its matching factory kit — step flashing woven into the courses one piece at a time so each hands water to the shingle below, with an adhesive underlayment beneath the whole assembly. It's also what keeps the warranty alive: VELUX's No Leak backing and Fakro's coverage both depend on the unit going in with its matched flashing kit, not a bead of roof cement.

If you're re-roofing, replace the skylights in the same job — it's the best-timed and cheapest moment there is. A tear-off disturbs and weakens the old skylight flashing whether anyone means to or not, and the only correct way to flash a skylight is to weave new flashing into the new shingle courses as they go on. It's also a warranty reality you should hear plainly: many roofers will reflash an old skylight kept through a re-roof but won't warranty it, and some require a signed waiver, because no one wants to own a leak that starts inside a 15-year-old unit they were told to leave. Replacing during the re-roof renews the skylight warranty and lines it up with the new roof's, so the whole detail — glass, seal, and flashing — is covered together.

On permits, swapping a unit into the existing opening is the lenient case: a same-size replacement doesn't touch the roof framing, so New Jersey treats it far more simply than cutting a brand-new hole, which alters the framing and generally needs a building permit with inspection. New Jersey's adopted IRC also requires safety glazing in a skylight (R308.6) — laminated or fully tempered glass — which every unit we set already meets. We confirm your town's specific rule up front and pull any permit under our NJHIC license (#13VH13970900) when the job calls for one. If you want a brand-new skylight cut in, or an active leak diagnosed first, that's our skylight installation and leak-repair page; this one is for replacing a unit that's already there.