Skylights and Solar Tubes in Claremont: Leaks, Seals, and Service Life

A skylight is a hole in the roof with a very good reason for existing. Done well it transforms a dark hallway or a north-facing kitchen. Done badly, or simply left alone for thirty years, it becomes the most reliable leak in the building.

The distinction is almost never the glass. It is the FLASHING, the seals and the curb - the assembly that joins a manufactured unit to a field-built roof. This piece extends the Claremont home maintenance guide to the one roof penetration owners actually look at every day.

Why skylights leak

Water gets in around a skylight for four broad reasons, and separating them matters because the repairs are entirely different.

The first is FLASHING failure. Flashing is the metal that weaves the unit into the roofing so water runs around and past it. When it corrodes, lifts, was installed poorly, or was disturbed during a re-roof, water gets underneath and the skylight gets the blame.

The second is SEALANT failure. Sealant around the frame, at the curb, and at flashing laps is fully exposed to sun, and it hardens, shrinks and cracks. It is a wear item, not a permanent bond.

The third is the UNIT itself: a failed glazing seal, a cracked acrylic dome, a degraded gasket, or a weep path that has clogged.

The fourth is not a leak at all. It is CONDENSATION - interior humidity meeting a cold glass surface and running down the shaft. It appears in cold weather, unrelated to rain, and it is a ventilation problem rather than a roofing one.

Telling condensation from a leak

The test is timing. Water that appears during or shortly after rain, or after irrigation hits a roof edge, is intrusion. Water that appears on a cold, dry morning - especially in a bathroom or kitchen, and especially near a shower - is condensation.

Condensation almost always points back to exhaust ventilation that is not moving moisture out of the building, which is the same root cause behind a surprising number of attic problems. That connection runs through the insulation guide, because insulation, air sealing and moisture in the roof cavity are one subject.

What Claremont conditions do to these units

Two forces dominate here, and neither is rain.

Ultraviolet exposure is relentless on anything at the top of a roof. Acrylic domes yellow, craze and eventually crack. Gaskets harden. Sealant reaches the end of its life sooner than the same product would in a shaded climate.

Thermal cycling does the rest. A skylight assembly heats hard through the afternoon and cools at night, every day, and the metal, the frame and the roofing all move at different rates. That daily flex is what opens laps, backs out fasteners and fatigues sealant.

Add the canopy. Leaf litter and seed debris collect on the uphill side of any roof penetration, dam water there, and hold moisture against the flashing. Keeping that clear is the same habit the canopy and roof guide argues for across the whole roof, and a skylight is where the cost of ignoring it shows up first.

Solar tubes, briefly

Tubular daylighting devices - solar tubes - solve a different problem. They deliver daylight to an interior room through a reflective tube with a small dome above and a diffuser below, with far less heat gain and far less structural disruption than a full skylight.

They still have a roof penetration, still have flashing, and still have a dome that ages in the sun. The common complaints are a dome that has clouded or cracked, debris and insects inside the tube or diffuser, and reduced light output that is usually dirt or degradation rather than failure.

Condensation inside the tube is the finding worth taking seriously, because it means humid air is reaching the assembly and the seal at the ceiling is not doing its job.

The inspection, mostly from the ground

You can learn most of what you need without a ladder.

From inside, look at the shaft walls and the ceiling perimeter for staining, discoloration, bubbling paint or soft drywall. Note whether marks are old and dry or currently damp - a photograph with a date settles arguments later. Check whether the glass has clouded or fogged between panes, which indicates a failed glazing seal.

From outside, use binoculars. Look at the dome or glass for cracking, crazing and yellowing. Look at the flashing for lifted edges, rust or visible sealant repairs. Look uphill of the unit for accumulated debris.

Operable units add a mechanical dimension: check that the crank, motor or remote still works and that the unit closes fully. A skylight that will not close is a leak with a schedule.

Repair, replace, or remove

Small sealant maintenance at accessible points is reasonable. Beyond that, this is roofing work.

Reflashing, replacing a unit, or altering a curb involves opening the roof assembly, and it should be done by a licensed roofing contractor. The timing question matters too: if the roof is nearing replacement, doing a skylight separately means paying twice to open the same area. Coordinating the two is usually the better economics.

Some owners choose to remove a skylight entirely and close the roof, particularly where an old unit sits over a bathroom and has caused repeated problems. That is a legitimate answer, and it is also a change to the roof assembly, so ask the City of Claremont about permitting rather than assuming a like-for-like swap and a removal are treated the same way.

Whatever gets done, put the paperwork in the file described in the owner's guide. Roof penetrations attract questions in a resale, and documented work answers them.

The bottom line

Skylights rarely fail at the glass. They fail at flashing, sealant and debris, and in this climate sun and daily thermal movement set the pace. Establish first whether you have intrusion or condensation, keep the uphill side clear, inspect from the ground with binoculars, coordinate any real repair with the roof's own timeline, and leave the roof assembly to a licensed roofer.

This is general information rather than a roofing opinion; a licensed contractor inspecting your actual installation governs. Anthony Grynchal has been licensed in California since November 2009.