How skylight installation works, step by step
Skylight installation starts with a roof inspection from the rooftop and from inside the attic, because the framing above your ceiling decides how wide the opening can be. Then we put a roof estimate in writing.
- We cut the opening through the shingle field and roof deck, then square it to the rafter or truss bays so the frame sits flat on the sheathing.
- A curb lifts the unit above the drainage plane, and that one detail is why a skylight stays waterproof through monsoon season.
- Step flashing is laced under each course along the sides, and counter-flashing caps the curb top and gets hand-sealed with sealant.
- Apron flashing closes the downhill face, while pipe flashing and the pipe boot around any plumbing stack keep that penetration dry.
- Synthetic underlayment covers the field, with ice-and-water shield at the eave, in valleys, and behind chimney flashing.
- We fasten with screws and ring-shank nails instead of overdriven nails, and we keep caulk out of spots where flashing should do the work.
Materials, roof types, and the flashing details that decide the job
What your roof is made of changes the flashing kit, the curb height, and how long the work takes. We carry the details for each system instead of improvising on your rooftop.
- On asphalt shingle roofs we tie into architectural shingle and three-tab shingle, matching color and exposure so the patch disappears.
- Wood shake and cedar shake need a taller curb and extra sealant, because the surface is uneven and traps debris.
- Slate, clay tile, and concrete tile are cut and reseated by hand; a cracked tile is a leak and a broken one is a callback.
- Metal panel and standing-seam panel roofs use a clamped curb instead of fasteners driven straight through the seam.
- Low-slope sections built with TPO, EPDM, or PVC membrane need a membrane boot and a termination bar, not shingle flashing.
- Built-up roof and modified bitumen assemblies get a self-adhered or torch-applied patch, then a UV-rated coating.
What we inspect, and what failure looks like
- Granule loss on an asphalt shingle means the mat is exposed and the roof is into end-of-life wear.
- Rot and decay in the sheathing or fascia usually trace back to a valley, dormer, or parapet that has drained badly for years.
- Sag along the roofline over a ridge beam or purlin points to a framing problem before it ever points to a leak.
- Daylight from the attic is a hole, not a slow leak, and it gets an emergency roof repair visit rather than a scheduled one.
- A clogged gutter and downspout push water under the drip edge and back up under the eave.
- Ventilation matters as much as the surface. Without airflow the attic bakes and the shingles above it age early.
- A vent boot cracked by UV usually shows up as a ceiling stain long before anyone sees the hole from outside.
- Compressed insulation and a missing vapor barrier let warm attic air condense on a cold skylight frame.
Timelines, cost drivers, and local conditions
A single skylight replacement is usually a one-day job. Cutting framing, adding a curb, and meeting building code clearances can push it to two.
- Labor runs longer on slate and tile than on asphalt shingle, because every unit comes up and goes back down by hand.
- Access drives price. A steep pitch, a second story, or a tight side yard means scaffold, ladder work, and a harness setup.
- Soft decking underneath means plywood or OSB sheathing repair, the most common surprise on an estimate.
- Phoenix averages about 111 days at or above 100 F, and that heat ages felt, tar paper, and roofing felt faster than rain ever does.