About Our Flat Roof Repair & Replacement Service
Flat and low-slope roofs fail differently than pitched roofs — water doesn't run off, it sits, so the membrane and its seams have to be genuinely watertight, not just water-shedding. We repair and replace flat roofs on homes, additions, porches, and small commercial buildings across New Jersey using TPO, EPDM rubber, and modified bitumen systems matched to the specific roof.
Why Flat Roofs Need a Different Approach
On a pitched roof, gravity does most of the waterproofing work — water runs off before it can find a way in. On a flat or low-slope roof, water sits on the surface and pools in low spots, so the roof has to be a continuous watertight membrane with seams that are genuinely sealed, not overlapped. This is why flat roofs can't use shingles, and why a flat roof leak is almost always a membrane or seam failure rather than a 'missing piece' you can spot from the ground.
The Three Flat Roof Systems We Install
There's no single best flat roof material — the right choice depends on the roof size, exposure, foot traffic, and budget. We install all three of the proven residential and light-commercial systems and recommend based on the specific roof rather than whatever we happen to stock.
- TPO: a single-ply white membrane that reflects heat (lower cooling costs), with heat-welded seams that are extremely strong. The current go-to for most flat roofs.
- EPDM rubber: a proven single-ply black membrane, decades of track record, economical and durable, slightly less reflective than TPO.
- Modified bitumen: a multi-ply asphalt-based system, excellent for roofs with foot traffic or complex detailing, torch- or self-adhered.
Ponding Water: The Flat Roof Killer
The most common reason flat roofs fail prematurely is ponding — water that sits in low spots for more than 48 hours after rain. Standing water accelerates membrane breakdown, finds the smallest seam weakness, and adds weight load. A good flat roof install corrects drainage by tapering insulation toward drains or adding crickets to redirect water. When we assess a failing flat roof, drainage is the first thing we look at, because a new membrane over an unaddressed ponding problem just fails again.
Repair or Replace?
Flat roofs are often repairable when the membrane body is sound and the problem is localized — a punctured spot, a failed seam, a deteriorated flashing at a wall or penetration. We can patch and re-seal these reliably. Full replacement makes sense when the membrane is broadly aged, brittle, or has been patched repeatedly, or when ponding has compromised large areas. We diagnose the actual condition and quote both options where both are realistic.
What's Included
- TPO, EPDM rubber & modified bitumen systems
- Flat roof leak detection & seam repair
- Ponding water & drainage correction
- Flashing & parapet detailing
- Home additions, porches, dormers & low-slope sections
Flat Roof Repair & Replacement — Common Questions
How much does flat roof replacement cost in NJ?
Flat roof pricing depends on the system (TPO, EPDM, or modified bitumen), the square footage, the insulation and drainage work needed, and access. Single-ply membranes like TPO and EPDM are priced per square foot installed; modified bitumen varies with the number of plies. Drainage correction, if needed, is a separate but important line item. We measure and quote on-site.
How long does a flat roof last?
A quality TPO or EPDM membrane lasts 20–30 years when properly installed and drained; modified bitumen is similar. The biggest variable is drainage — a flat roof that ponds water fails far sooner than one that drains within 48 hours of rain. Proper slope and drainage detailing is what separates a 25-year flat roof from a 12-year one.
Why does my flat roof keep leaking after repairs?
Usually one of two reasons: the actual leak source was never found (water travels under a membrane and surfaces far from the entry point), or there's an unaddressed ponding problem that keeps stressing the same area. We use proper leak detection to find the real entry point and check drainage before repairing, so the fix actually holds.
Which is better — TPO or EPDM?
Both are excellent; the right one depends on the roof. TPO's white surface reflects heat and lowers cooling costs, with very strong heat-welded seams — it's our most common recommendation. EPDM (black rubber) has a longer track record and is economical and durable, though less reflective. We recommend based on your roof's exposure, size, and budget rather than a one-size-fits-all answer.
Flat Roof Repair & Replacement by Location
Dedicated flat roof repair & replacement pages for the counties and cities where we do most of this work — written with local code, weather, and neighborhood context.
By County