EPDM Roofing Contractors – Keystone Commercial Roofing

EPDM Roofing Contractors for Commercial Roofs in New York

If your commercial roof is already EPDM, whether ballasted or not, Keystone Commercial Roofing assesses the existing roof and determines whether repair or replacement is appropriate.

$2M general liability insurance

MBE, DBE and LBE certified

OSHA-compliant safety practices

Commercial roofing since 2004

What EPDM Is, and the One Property That Changes Everything

EPDM is a cured synthetic rubber membrane. It cures once, during manufacturing, and keeps that chemistry for the rest of its life on the roof.

That’s the fact that shapes everything else about it. Thermoplastic membranes soften with heat and weld at the seams. EPDM doesn’t become weldable that way, its seams join with adhesive and seam tape instead, a cold process used for both the original install and every repair after it.

On an EPDM roof:

Black is standard; white or grey shows up less often
Seams are taped and glued, never heat-welded
Insulation sits underneath, and on some older New York buildings, a layer of loose stone ballast sits on top of that

What’s under the ballast is the part nobody checks until something leaks.

Seams Without Heat - Where an EPDM Roof Needs Watching

EPDM seams are joined with adhesive and seam tape, not heat. That bond ages on its own timeline, different from a welded seam, and it’s worth knowing what normal wear looks like versus a seam that’s actually failing.

Where seams age first

Ends of a lap
Corners and parapets
Around pipes, drains, and other penetrations
Anywhere the sheet has shrunk and pulled tight over time

What a failing seam looks like

A visible gap or a lifted edge along the lap line, sometimes with a slight curl where the tape has let go. That’s different from a puncture or split in the field of the sheet, and the two are easy to confuse from the ground.

Most seam wear is gradual. Some isn’t, an installation defect, physical damage, or sudden deck movement can cause a seam to fail abruptly rather than age out slowly. Either way, it’s not something you diagnose from the ground.

Ballasted Roofs, and What's Under the Stone

Loose stone ballast shows up on older EPDM roofs across New York, a holdover from an era when ballasted systems were a common specification for large flat roofs.

Why buildings have it

Ballast holds the membrane down through weight alone, no fasteners, no adhesive. That's a straightforward, low-disturbance installation, and it's still common across the city's older commercial and multifamily stock.

Why it complicates a leak

The stone hides the membrane completely. Water rarely enters where the stain shows up inside:

It can travel along the membrane surface
It can move within the insulation layer
It can pass between components

Depending on how the assembly is built, so the entry point on the roof and the stain inside can be many feet apart.

How it actually gets found:

Sometimes electronic leak detection or an infrared survey narrows the area first. Sometimes ballast comes back from the suspect spot directly. Either way, it's a survey, not a guess from the parapet.
On an occupied building, that work is staged: cleared access, controlled disposal of the stone, and a plan for putting it back once the membrane underneath is repaired.

Ballasted roof and a leak you can’t place? That’s a survey, not a guess.

Fixing It Down, and Fixing It Up

EPDM goes down three ways. Which one applies depends on the deck, the building, and what the roof needs to carry.

Method	How it holds
Fully adhered	Bonded directly to the substrate with adhesive across the full surface
Mechanically attached	Fastened through to the deck or insulation at intervals, then seamed
Ballasted	Held down by the weight of stone or pavers, no fasteners or adhesive

Repairing an existing roof

Usually means cleaning the old surface, applying fresh primer and adhesive, and lapping new material or tape directly onto what's already there. That holds up well on a roof that's still sound underneath the wear.

When a roof stops holding a patch

When the membrane itself has degraded past the point where adhesive can grip it reliably, brittle, cracked, or too far gone at the surface for a bond to take. That's a condition question we answer on site, not over the phone.

Ballasted roof and a leak you can’t place? That’s a survey, not a guess.

EPDM on New York Buildings

EPDM shows up across older multifamily and industrial buildings citywide, and it’s a common membrane behind the age and building-stock profile of the Bronx specifically, older low-slope roofs on tight capital budgets, where seam condition and ballast inspection come up regularly.

Working over an occupied building means:

Staged material and ballast storage
Controlled access for tenants and deliveries below
Scheduling around a building that doesn’t stop running while the roof does

Where EPDM fits, and where it doesn’t: it’s usually the sensible answer on a roof that already has it, keeping the existing assembly intact through repair or a straightforward replacement. Grease or chemical exposure changes that calculation, and the right call there depends on the specific exposure, its concentration and duration, and the membrane manufacturer’s compatibility guidance, not on this membrane alone. See how the three single-ply membranes compare for that decision.

FAQs

How do you find a leak under a ballasted roof?

By narrowing the search first, sometimes with electronic leak detection or an infrared survey, then pulling back ballast from the likely area to confirm it. Guessing from the interior stain alone isn’t reliable, since water travels before it drips.

Can an EPDM roof still be repaired if the seams are old?

Often, yes. If the membrane itself is still sound, new adhesive and tape can be applied directly over a cleaned, prepared lap. Whether that holds depends on the sheet’s condition, which we check on site.

Do EPDM seams get heat-welded like other membranes?

No. EPDM seams are joined with adhesive and seam tape, a cold process used for both original installation and later repairs.

Are you insured for ballast removal work on an occupied building?

Yes, $2 million in general liability coverage, and our crews follow OSHA safety practices for the access and dust control that ballast work requires.

Is EPDM still the right choice for every commercial roof?

Not for every one. It’s a strong fit for a roof that already has it. Grease or chemical exposure is a separate question that depends on the specifics of what’s landing on the roof.

Send a photo of a seam or the ballast area, and the building address.

We’ll tell you what we’re looking at and whether repair is still realistic.