Underlayment Delamination Identification and Mitigation

Energy Products Application Note - December 13, 2024

Overview

It was recently discovered that the Tesla Class A Underlayment (Part Number: 1613738-03-X) can wrinkle upon direct sun exposure on a 90°+ day, mostly on south-facing mounting planes. This observation was made independent of the duration of the sun exposure.

Root Cause

The reason behind the delamination of the underlayment is that the facer expands upon heat exposure, leading to the “frustration” of the material and debonding from the fire layer perpendicular to the deck which will then cause the wrinkles on the underlayment.

Identifying Delaminated Underlayments

The images below show examples of the wrinkled underlayment for identification purposes.

Please note that the cases shown here, or any similar ones, do not require any course of action or mitigation steps, since even though the facer does perform some of the water shedding, the majority of the (nail) sealing of the roof comes from the adhesive below the fire layer. As long as the facer is not ripped or torn and is lapped properly, it is still functional in its water shedding capability. The more severe cases and their solutions are described in the section below.

Risks and Solutions Identified

  1. A punctured facer section above a hole patch or any reverse lapped detail would allow water to bypass.
    • Solution: Remove any hole patches that are over a wrinkled section. Then, remove a section of the facer around it and adhere a new underlayment patch directly to the exposed fire barrier using a roller and a heat gun.
  2. A torn facer layer would trap the water in, creating a balloon of water over a fastened tile foot.
    • Solution: Since the underlayment is certified as ice dam protecting, the adhesive on the bottom seals the fasteners and does not allow water through the nail penetration in the event a balloon occurs.

Future Status

A new Tesla underlayment (Part Number: 1947922-00-X) was recently launched that was developed in collaboration with a new manufacturer without the face layer.