Roof Coating & Restoration
Silicone and acrylic coatings that extend the life of a sound flat roof and make it reflective, applied only after seams and flashings are fixed.
Learn moreModified bitumen roofs for New York, NY rowhouses and terraces
Two layers of reinforced asphalt membrane, built into a roof that takes foot traffic, dropped tools and rooftop furniture. We install and repair modified bitumen, including flame-free systems.
- We answer 24/7
- Cold and self-adhered
- Two-ply systems
Quick answer: Modified bitumen is an asphalt membrane reinforced with polyester or fiberglass and modified with polymers for flexibility. In New York, NY it is usually installed as a two-ply system, a base sheet under a granulated cap sheet, and suits rowhouse roofs, terraces and roofs with regular foot traffic.
What the job involves
Why two plies hold up under foot traffic
Single-ply membranes rely on one sheet. Modified bitumen builds the roof from a base sheet and a cap sheet, so a puncture through the top layer does not have to become a leak. The granulated cap sheet also shields the asphalt from sun and scuffs.
How the sheets are bonded matters as much as the sheets. Torch application uses open flame, a real fire risk at wood decks, parapets and roof edges. Cold adhesive and self-adhered sheets avoid the flame altogether, which is why many occupied city buildings use them.
Your options
Torch, cold adhesive or self-Adhered?
| Method | Strengths | Drawbacks |
|---|---|---|
| Torch-applied | Fast bond, works in cool weather. | Open flame on the roof, a fire risk at wood decks, parapets and edges. |
| Cold adhesive | No flame, suited to occupied buildings. | Slower cure, and sensitive to weather while curing. |
| Self-adhered | No flame, clean and quick. | Needs dry conditions and suitable temperatures to bond. |
Cost factors
What a modified bitumen roof costs depends on
Bonding method
Cold adhesive, self-adhered and torch systems differ in labor and material.
Number of plies
Two-ply is standard. A three-ply build costs more.
Cap sheet
White or reflective granulated caps cost more than standard.
Insulation
Meeting energy code above the deck is a large share of the material.
Tear-off
Old built-up and asphalt roofs are heavy to remove.
Details
Parapets, skylights and bulkheads each need their own flashing.
Typical range: Published 2026 New York figures for commercial low-slope re-roofs run from about $6 per sq ft for a ballasted EPDM overlay to about $24 per sq ft for 3-ply modified bitumen with R-30 insulation. Rowhouse roofs are smaller and priced differently; a planning figure, not a quote.
Variations of the job
Modified bitumen systems we install
Cold-applied systems
Sheets set in cold adhesive rather than heat. It is slower to cure, but there is no flame, which suits occupied buildings and roofs over wood decks.
Self-adhered cap sheet
A peel-and-stick cap sheet bonds as it is rolled into place. Clean, quick and flame-free, though it needs dry conditions and suitable temperatures to bond fully.
Granulated cap sheet
Mineral granules on the top layer protect the asphalt from sun and take foot traffic. White or reflective granulated caps help the roof meet the city's reflectivity rules.
Two-ply systems
A base sheet and a cap sheet with staggered laps, so no seam in the top layer sits over a seam below. The standard build for a durable rowhouse roof.
Local conditions
Brownstone roofs that carry equipment
In the Park Slope Historic District, the Landmarks Preservation Commission has signed off flat roof replacements with vents, condensing units and railings under a Certificate of No Effect, the usual route for roof work that cannot be seen from the street. Roofs like that carry equipment and the people who walk up to service it, which is exactly where a two-ply modified bitumen roof with a tough cap sheet earns its place.
How it runs
How a modified bitumen roof is built
- 1
Prepare the deck
Tear-off, deck repairs and a clean, dry surface.
- 2
Insulation and cover board
Fastened down, with taper where the roof needs slope.
- 3
Base sheet
Adhered with laps offset from the cover board joints.
- 4
Cap sheet
Laps staggered from the base sheet and rolled for full contact.
- 5
Flashings and final check
Two-ply flashings at walls and curbs, then a lap-by-lap check.
Modified bitumen makers you will find on city roofs. Repairs are matched to the cap sheet already in place.
SiplastSopremaPolyglassGAFIKOJohns ManvilleCertainTeedTremco
Questions we hear
Modified bitumen questions
No. Tar and gravel, or built-up roofing, uses layers of felt and hot asphalt. Modified bitumen uses factory-made sheets modified with polymers, which makes them more flexible and more consistent.
Torching works, but open flame near wood decks, parapets and roof edges is a fire risk. Cold-applied and self-adhered systems remove that risk and are often the better choice on occupied buildings.
Yes. White granulated cap sheets and reflective coatings are both available, and one of them is usually needed to meet the city's reflectivity rules.
The damaged area is cleaned and a new cap sheet section is set in compatible adhesive over it, with laps rebuilt. Roof cement smeared on top does not last.
It is one of the more durable choices under foot traffic, though pavers or decking should sit on pedestals or protection board so they do not wear the cap sheet.
Related services
Related roofing work
Liquid-Applied Roof Waterproofing
Fluid-applied membranes for crowded roofs where sheet goods cannot reach: around dunnage, pipe clusters, railings and odd penetrations.
Learn moreRoof Deck & Terrace Waterproofing
Leaks under a terrace are waterproofing leaks. We lift the pavers or decking, rebuild the membrane and drainage beneath, and put the surface back.
Learn moreNeed a roof that takes a beating?
Call for a roof survey and a two-ply modified bitumen quote.