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Mansards, dormers, canopies, and other pitched sections on commercial buildings, installed and repaired by the same crew that handles the flat roof beside them.
$2M general liability insurance
Asphalt shingle roofing on a New York commercial building almost always covers a pitched section, a mansard, a dormer row, an entrance canopy, sitting above or beside a much larger flat roof. Keystone Commercial Roofing installs, repairs, and maintains both surfaces as one job, so the transition between them, where leaks can be especially difficult to trace, stays the responsibility of a single crew instead of two.
Very few commercial roofs in New York run entirely on asphalt shingles. Almost every building that has them pairs a pitched section with a much larger flat roof somewhere else on the same structure.
Mansards and dormer rows sit on older multifamily and mixed-use buildings, often as the only part of the roof visible from street level. Porticos, entrance canopies, and covered walkways add a small shingled surface to an otherwise flat-roofed property, usually right where tenants and visitors pass underneath.
Walk-ups and small multifamily buildings can carry a shingled front slope over a flat rear section, leaving two different roof systems on the same building. Keystone Commercial Roofing handles both sides of that roof instead of treating the transition as someone else’s scope. Institutional buildings, schools, municipal offices, healthcare facilities, sometimes carry a pitched chapel roof, a portico, or a dormer row above an otherwise low-slope field.
Here’s how the three hold up on the details that actually change a specification, past the summary above.
| Categories | TPO | PVC | EPDM |
|---|---|---|---|
| Seam method | Heat-welded | Heat-welded | Taped or adhered |
| Standard color | White | White | Black (white available) |
| Chemical & grease resistance | Depends on formulation and exposure | Generally stronger resistance to many oils, greases and chemicals | May be unsuitable for some petroleum-based exposures |
| Typical fit | General low-slope roofs, reflectivity a priority | Kitchen venting, rooftop mechanical exposure | Standard exposure, simpler install |
Seams. TPO and PVC seams are heat-welded, fusing the sheets into one continuous membrane instead of relying on a separate bonding material. EPDM seams rely on tape or adhesive systems, so seam prep and installation quality matter more.
Attachment. Single-ply membranes can be mechanically attached, fully adhered or ballasted depending on the approved roof assembly, deck, building height and wind exposure. The specific attachment method is determined by the system specification and site conditions.
Color and reflectivity. TPO and PVC are commonly available in white, while EPDM is commonly black. Available colors vary by manufacturer and product.
Chemical, grease and exhaust exposure. PVC generally offers stronger resistance to many oils, greases and chemicals than TPO or EPDM, which is why you’ll see it on roofs that take on grease, oils or exhaust: restaurant kitchens venting through the roof, or buildings with mechanical equipment that leaks fluids. TPO suitability depends on the specific chemical or grease exposure and membrane formulation. Petroleum-based exposure can attack EPDM, which typically makes it a poor fit for roofs with heavy kitchen or industrial venting.
Foot traffic and rooftop equipment. Rooftop units, walkway pads and regular foot traffic wear down any membrane over time. TPO and PVC can be repaired using compatible membrane and heat-welding methods, while EPDM repairs use the same tape-and-adhesive method as the original seams.
Where each gets specified. TPO is a common fit for low-slope commercial roofs where chemical exposure stays moderate and a reflective, heat-welded surface is the priority. Specify PVC where grease, oils or chemical exposure would put TPO or EPDM at risk. EPDM fits roofs without that exposure, where its installation approach and long field track record fit the building.
Comparing two quotes on different systems? Send us both and we’ll tell you what’s actually different about them.
The transition where a shingled slope meets a flat roof is the busiest square foot on the building. Water sheds off the pitched section, concentrates at the change of plane, and finds the first opening available.
Valleys carry more water than any other part of a pitched roof, and a valley that empties directly onto a flat membrane needs a detail that neither roof type resolves on its own.
The area along the eave is particularly exposed to winter moisture and ice-dam conditions, which is why the underlayment and flashing details there matter. Leaks on mixed pitched-and-flat roofs can originate at this change of plane, where the two roof systems have to work together, and it’s the reason a shingle specialist and a flat-roof contractor working separately tend to point at each other’s roof.
We handle the flashings at the transition and the shingle work on either side of it as one scope, with one crew responsible for the result.
Leaking where the pitched section meets the flat roof? Send a photo of the join and the building address.
Deck and sheathing carry the structural load and give shingles something solid to fasten into. On older buildings, this layer is often the first thing to fail once water gets past a lifted shingle.
Underlayment provides a secondary water-shedding layer beneath the shingles, helping protect the deck when moisture gets past the primary roof covering.
A pitched section needs its own ventilation path, separate from whatever the flat roof beside it uses, or trapped heat and moisture shorten the life of the deck from underneath. Fastening pattern and exposure, how far each course sits below the one above it, decide how well a shingle roof holds up in wind, and it’s usually the first thing worth checking after a storm.
A damaged section, torn, lifted, or missing after wind, is usually a straightforward repair, matched into the existing field rather than replaced wall to wall.
Going over an existing layer is sometimes possible, but it depends on the condition of what’s underneath, the local code, and what the structure was built to carry.
That’s worth getting in writing, not assuming. A full strip may become necessary when the deck is compromised, the existing roof has reached its serviceable limit, or the permitted roof assembly cannot accommodate another layer. What the deck can support, and what the code allows, decide this question.
Been told the whole slope needs to come off? Worth a second opinion before it does.
For a closer look at what’s actually happening under the surface, a survey of the deck and the transition settles the repair-or-replace question before any work starts. Where a repair turns into scheduled roof repair or a full roof installation and replacement depends on what that inspection finds. A shingled section that’s failed outright after a storm falls under 24/7 emergency roof repair instead of a scheduled visit.
Keystone Commercial Roofing works on shingled pitched sections across Manhattan, Brooklyn, Queens, the Bronx, Staten Island, Westchester County, and Nassau County, always alongside the flat roof most of these buildings also carry.
See commercial roofing in Brooklyn and commercial roofing in the Bronx, or browse all roofing systems we install and repair. For the crew behind this work, visit commercial roofing contractors in NYC.
Call (646) 851-3145, or send a photo of the transition, the valley, or the damaged section.
Yes. Most buildings with a shingled section also carry a flat roof somewhere else on the structure, and the transition between the two can be the hardest place to trace a leak. One crew handles both.
Sometimes, depending on the condition of the existing layers, the deck underneath, and what local code allows on that building. An inspection settles it either way.
Yes. We carry $2 million in general liability insurance, and our crews follow OSHA-compliant safety practices. Storm damage to a pitched section often needs a fast response, and coverage is confirmed against the specific job before work starts.
Yes. A pitched roof needs a ventilation path separate from whatever the adjoining flat roof uses. Without it, trapped heat and moisture shorten the deck’s life from underneath, regardless of how sound the shingles above it are.
Far more often than the shingles themselves, the leak starts at a valley, an eave, or the point where the pitched section meets a flat roof or a wall.
Commercial roofing across Manhattan, Brooklyn, the Bronx, Queens, Staten Island, Westchester, and Nassau. MBE, DBE, and LBE certified, OSHA-compliant crews, and $2 million in general liability coverage since 2004.
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