Parapet Wall Flashing in Single-Ply Roofing: What You Need to Know

Parapet walls are a common feature on commercial flat roofs across Colorado and Georgia. When paired with a single-ply membrane system like TPO, PVC, or EPDM, parapet wall flashing becomes one of the most critical waterproofing details on the roof.

If the flashing fails, water doesn’t just hit insulation—it can run behind walls and into the building envelope.

Here’s what property owners, facility managers, and commercial roofing contractors need to know.

What Is Parapet Wall Flashing?

Parapet wall flashing refers to the transition between the roof membrane and the vertical wall at the roof edge. It prevents water from entering the roof assembly where the membrane turns up and terminates on the wall.

This area is highly vulnerable due to:

• Expansion/contraction from heat and cold

• Wind uplift pressures

• UV exposure

• Water runoff from upper walls or equipment

Code Requirements for Parapet Flashing

According to the International Building Code (IBC), parapet wall flashing must meet several performance standards:

• Membrane terminations must be watertight.

• Flashing height must extend a minimum of 8 inches above the finished roof surface unless otherwise allowed by manufacturer specs or local codes.

• Cap flashings (metal coping or counterflashing) are required to protect the top edge of the membrane from UV degradation.

RoofNuts follows NRCA and IBC guidelines to ensure flashing installations withstand decades of thermal movement and exposure.

Flashing System Options

1. Fully Adhered Membrane with Termination Bar

• Membrane extends up wall

• Mechanically fastened with termination bar

• Sealed with manufacturer-approved sealant

• Protected by metal counterflashing

2. Wrapped and Welded into Wall Substrate

• Used when wall is concrete or CMU

• Heat-welded (for TPO/PVC) or bonded (EPDM)

• Counterflashing not always required

3. Prefabricated Metal Copings with Heat-Welded Flashing

• Ideal for parapets with cap width >6"

• Provides clean finish and edge protection

• FM-rated systems often require this detail

Best Practices for Installation

• Use 60-mil or thicker membrane for vertical applications

• Always clean and prime wall surfaces before adhering

• Avoid stretching membrane at inside corners—use pre-formed corners or gussets

• Install termination bar 1–2" from membrane edge for sealant placement

• Use continuous metal counterflashing or coping over the top of the wall

Common Flashing Failures (and How to Prevent Them)

• Loose termination bar: Always use manufacturer-specified fasteners with proper spacing

• Open laps at corners: Use prefabricated inside/outside corners or reinforce with cover strips

• Sealant deterioration: Use high-performance sealants rated for UV and ozone exposure

• Coping blow-off: Ensure all metal coping is fastened with cleats or continuous clips per FM 4435 standards

FAQ: Parapet Wall Flashing for Single-Ply Roofs

What height should flashing go up the parapet wall?

Flashing should extend at least 8 inches above the finished roof surface per code, though 12 inches is preferred for better protection.

Do all parapet walls need metal coping?

Not always, but metal coping is the most durable and code-compliant way to protect the top of a parapet from water intrusion.

Can TPO be heat-welded directly to a brick wall?

It can, but surface prep is critical. Many contractors install a metal receiver or flashing plate to create a better bond.

Serving Colorado and Georgia

At RoofNuts, we specialize in commercial roof flashing solutions across:

• Colorado: Denver, Colorado Springs, Aurora, Fort Collins, Lakewood

• Georgia: Atlanta, Augusta, Savannah, Macon, Athens

We install and repair TPO, PVC, and EPDM systems with expert attention to wall flashing, drains, curbs, and penetrations.

📞 Colorado Office: 303-276-2403
🌐 https://RoofNutsCO.com
📞 Georgia Office: 404-476-6851
🌐 https://RoofNutsGA.com

Want a roof that lasts? Get your parapet walls flashed right the first time. Call us today for a free evaluation.