Where torch down roofing fails, and what repair actually means
Torch down roofing is the common name for torch-applied modified bitumen: APP or SBS sheets heated with a propane torch and bonded to a base sheet. It is the most common flat roof in New York, and most mod bit roof leaks are not in the field of the sheet. They are at the laps, the seams and the flashings — the places where one piece of membrane has to bond to another or to a wall.
A modified bitumen roof repair done with mastic and a patch over the old granules will separate in one freeze-thaw season. Granules are there to shed sunlight, not to be bonded to. The correct torch down roof repair cuts out the failed lap or blister, primes the exposed base, and torches a new cap sheet in with proper bleed-out at every edge so the repair is one membrane again.
Our torching crews are in-house. The people reflashing your curbs and parapets work for us, carry fire-watch procedures on every job, and answer for the detail later. That is the difference between a flat roof repair that lasts and one that needs a second contractor to fix the first.
Torch down and mod bit repairs we do
Seam & Lap Rebuilds
Open side laps and end laps are the number one source of leaks on a torch down roof. We cut back to a bonded edge, prime and torch a new cap strip with visible bleed-out — the sign that the asphalt actually flowed and bonded.
Blisters, Splits & Alligatoring
Blisters are trapped moisture or air under the cap sheet; splits follow movement in the deck; alligatoring is sun-cooked asphalt that has lost its oils. Each gets a different modified bitumen roof repair, and we tell you which one you have before we start.
Flashing & Parapet Terminations
Where the mod bit roof turns up a parapet or a curb is where water gets in. We rebuild base and cap flashing in the same system, terminate under new counterflashing and use liquid PMMA at details too tight to torch.
Repair or Full Replacement
When a section is beyond repair we say so. Options include a partial replacement of the failed area, a recover where the deck and insulation are dry, or a new cold-applied SBS or PMMA system where open flame is not appropriate for the building.
Free Torch Down Inspection
We walk the roof, probe laps, check every flashing and take a core sample where the insulation may be wet. You get photos and a written assessment at no charge, across Manhattan, Brooklyn, Queens and the Bronx.
In-House Torching Crews
No subcontracted torch work. Our own roofers hold the fire-watch procedures, carry the extinguishers and stay the required time after the last pass. On an occupied building that is not a formality.
Recent NYC projects
Seam & Flashing Rebuilds: torch down roof repair, step by step
Free Torch Down Inspection. We assess the whole mod bit roof, not just the area under the leak — laps, seams, flashings, drains and a core where wetness is suspected. A torch down roofing repair on a roof with saturated insulation only moves the problem.
Written scope: repair, section replacement or full replacement, with the reasoning. The estimate says which laps and flashings are being rebuilt and why, or why the section needs to come out.
Fire-safe torching by in-house crews, DOB-compliant. Combustible areas are protected, a fire watch stays on the roof after the last torch pass, and cold-applied modified bitumen is used where open flame is not appropriate.
Flashing and edge metal rebuilt. Base and cap flashing are torched in at every parapet and curb, counterflashing and edge metal are replaced where corroded, and PMMA liquid flashing is used at details that cannot be sheet-flashed.
Close-out photos and maintenance notes. You get before-and-after photos, a roof plan marking the repairs, and a short list of what to watch so the modified bitumen roof keeps performing.
What NYC building owners say
Mod bit roof leaking at the seams?
Free torch down roof inspection across Manhattan, Brooklyn, Queens and the Bronx.
Keeping a modified bitumen roof in service
A torch down roof that is walked twice a year and kept draining will outlast one that is ignored by a decade. The checks are simple and most of them are free.
A maintained modified bitumen roof delivers 20+ years of service. Most of the torch down roofing we replace failed early because nobody looked at the laps.
Frequently Asked Questions
In-house torching crews. Rebuilt laps that hold.
Torch down roofing repaired the way it was meant to be installed.
Related: Flat Roof Repair in NYC