Boston & North Shore Roofing
Skylight Installation and Leak Repair in Boston, MA
A skylight is a hole in your roof held shut by metal. We set new units with the manufacturer's flashing kit, rebuild the openings somebody sealed with tar, and run water over the finished job before we pack up.
- Manufacturer flashing kits, never roof tar
- Ice and water membrane around every opening
- Deck-mounted and curb-mounted units installed
- Water tested before we call it done
A skylight is a hole cut in your roof. Built right, it lights a dark stair hall for twenty-five years. Built wrong, it puts water on your ceiling the first time rain comes in sideways.
Most skylight leaks we open up are not the skylight. They are the flashing around it, or a smear of black roof cement where a flashing kit belonged.
We install, reflash and replace skylights across Boston and the surrounding towns, from flat three-decker center decks to North Shore capes.
- Manufacturer flashing kits, never roof tar
- Ice and water membrane around every opening
- Deck-mounted and curb-mounted units installed
- Water tested before we call it done
Free Skylight Installation & Repair Estimate
Know The Signs
Signs your skylight is the problem
Water travels before it shows. These patterns point back to the unit or its joints.
It only leaks in wind-driven rain
Straight-down rain sheds fine. A nor'easter pushes water uphill under the head flashing. That is a [flashing joint to rebuild](/services/roof-flashing-chimney-repair-boston/).
Haze between the panes
A failed insulated glass seal, not a roof leak. The gas fill is gone and the fog is permanent.
Drips on cold, clear nights
No rain, no leak. Warm moist air is hitting cold glass. That is a ventilation problem, not a flashing problem.
Stains low in the light shaft
The shaft acts like a chimney for warm house air. Brown corners usually mean the well was never insulated or air sealed.
Ice piles above the unit each winter
A skylight interrupts the meltwater path. Ice builds uphill of it, backs under the shingles and finds the flashing from behind.
Three kinds of skylight, three different failures
- Deck-mounted glass sits right on the sheathing with a factory flashing kit. It fails at the head flashing when the kit gets skipped.
- Curb-mounted units sit on a wood curb off the deck. They fail when the curb is too short for the snow piling against it.
- Sun tunnels are a dome and a reflective tube. They fail at the roof flashing and at the attic joints, where condensation collects.
The flashing kit is the product
Manufacturers sell a flashing kit matched to the unit and to your roof covering, because the joint is where skylights leak. We install VELUX units with the VELUX kit. Step pieces go in one per course, woven with the field. There is no caulk-only skylight install.
Skylights and ice: the Cape problem
Boston hits freezing about 92 days a year but only about 23 stay frozen all day, and that 69-day gap is a freeze-thaw machine. The story-and-a-half Cape is the worst case here: rooms directly under the deck, almost no eave ventilation, a skylight sitting in the warm zone. The heat is the cause, not the unit. Fixing it takes attic ventilation and insulation work alongside new metal.
780 CMR R905.1.2 runs an ice barrier from the lowest roof edge to 24 inches inside the exterior wall line, and 36 inches along the slope at 8:12 or steeper. That protects the eave, not a unit sitting mid-slope. So we membrane the opening itself.
Flat center decks, mansards and plastic bubbles
The three-decker matured around 1890 in Dorchester, and most survivors carry a near-flat center deck over the stair hall. That is where the old acrylic bubble lives, crazed and one branch from cracking. On rubber, the curb needs height above the membrane so drifted snow never sits against the joint. The 780 CMR table puts Dorchester and the rest of Boston at 40 psf.
A mansard is two roofs: slate or metal on the near-vertical face, low-slope membrane on the flat top behind it. In the South End, skylights sit on that hidden top and belong in the same scope as the membrane.
Historic districts and what the street can see
In a Landmarks district, approval lands before ISD issues a permit. That covers Historic Beacon Hill, the Back Bay Architectural District, the South End Landmark District and Bay Village. A flat unit behind a mansard is usually invisible from the street. A bubble on a visible slope is a longer conversation, and our guide to roof approval in a Boston historic district covers it.
Change the skylight when you change the roof
A glass unit and an asphalt roof age on similar clocks. One of our Google reviews is exactly that job: a full roof replacement with a skylight, priced together, done once. If you are planning a full roof replacement in Boston or a flat roof replacement in EPDM rubber, decide the skylight now.
Our Process
How we put a skylight in and keep it dry
Same order every time, inside and out, so water has nowhere to go but off the roof.
Site it from both sides
We read the rafter layout from the attic before picking a size. A unit landing inside an existing bay cuts no framing at all.
Frame the opening
Cut rafters get doubled headers and sistered trimmers. On board-sheathed roofs we back-block the cut edges so nothing flexes underfoot.
Dry in before the unit goes on
Ice and water membrane wraps the opening, up both sides and over the head, lapped shingle-style. That layer saves you if the metal ever fails.
Set the unit and its matched kit
Sill piece first, step pieces woven one per shingle course, head flashing and saddle last. Nothing substituted with tar.
Insulate and close the shaft
The light well gets insulation and an air barrier before drywall. A shaft open to attic air will drip and blame the skylight.
Water test, then sweep
A hose from the low side up, one zone at a time, someone watching inside. Then a rolling magnet over the ground.
On The Roof
What skylight installation & repair looks like in progress
What Drives The Price
What drives skylight cost in Greater Boston
A skylight job is three prices in one: the unit, the roof work, the interior work.
Deck-mounted or curb-mounted
Deck-mounted units sit low on a shingled slope with a matched kit. Curb-mounted units need a curb built, wrapped and flashed.
The glazing package
Laminated glass, low-E coatings, argon fill, factory blinds and solar-powered venting units with rain sensors all move the number.
What roof it lands in
Asphalt is straightforward. Slate means cutting and hooking pieces around the opening. Standing seam and rubber membrane are different details.
New opening or a swap
A unit dropped into its own existing opening is often a day. A new opening adds framing, drywall, tape and paint.
Access, staging and salt air
Four stories of staging on a three-decker costs more than a ranch. Within 3,000 feet of saltwater we use 300-series stainless fasteners.
Cost drivers, not a quote. We price after somebody measures the opening and checks the rafters from the attic side. Paulo Silva writes every estimate.
FAQ
Skylight Installation & Repair questions we get asked
Straight answers, including the ones that cost us work sometimes.
Almost always the head flashing at the top of the unit, or courses above it never woven into the step pieces. Wind drives water uphill under the lap.
Usually. If the glass and frame are sound, we strip the joint, rebuild the flashing in new metal and water test it.
Yes. A cathedral ceiling is easier, no shaft to build. We check rafter depth first, since insulation and a vent channel still have to fit.
A new opening involves framing, so it is permitted work. A straight swap usually falls under the roof permit, an ISD Short-Form at $20 plus $10 per $1,000 of work.
Glass units run twenty to thirty years. Acrylic domes go brittle sooner. We swap them during a reroof so nobody opens the same roof twice.
Related roofing services
Work that often comes up on the same roof.
- Flashing & Chimney RepairStep, counter and cricket flashing rebuilt at chimneys, sidewalls and parapets. Crown and mortar repair above the roof line, water tested before we leave.Learn more
- Attic Ventilation & InsulationRidge and soffit venting, rafter baffles, ceiling air sealing and attic insulation. We fix what causes ice dams, not just the ice.Learn more
- Roof ReplacementFull tear-off, deck repair and a code-correct ice barrier. Written scope, permit filed for you, magnet sweep at the end of every day.Learn more
Read more before you decide
Longer guides on the parts of this that homeowners ask about most.
- Historic RoofingReplacing a Roof in Beacon Hill, Back Bay or the South End: Landmarks Commission Approval FirstDesign review is not a formality you handle later — Boston is explicit that Landmarks approval comes before the building permit. Here are the districts, what gets reviewed on a roof, and how to sequence the job.6 min read
- DiagnosisWhy Does My Roof Leak Only in Heavy Rain? The Flashing Failures Behind Boston LeaksIf your ceiling stains during a nor'easter but stays dry in a drizzle, the shingle field is probably fine. Six failure points that only leak under volume, wind, or both — and why the stain is never under the hole.5 min read
Skylight Installation & Repair across Greater Boston
We run this service in 34 communities. Here is where it comes up most often:
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- 5.0 from 4 Google reviews
- Licensed & fully insured in Massachusetts
- Written workmanship warranty on every roof
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