Installing Self-Adhering Underlayments Direct-to-Deck: Pros and Cons - January 2023

Mon, Jan 16, 2023 at 8:00AM

Greg Keeler, Technical Services Leader, Owens Corning Science & Technology

If you’re a roofing contractor in South Florida, you’re certainly aware of the quandary that is posed when confronted with underlayment options. This is especially true when it comes to use of a self-adhering underlayment.

The recent landfall of Hurricane Ian in Southwest Florida was a stark reminder of the perils that face homeowners in South Florida. We’ve all witnessed scenes of widespread damage to roof coverings of all types: tile, metal panels, asphalt shingles, etc. Thus, the topic of how to protect the roof deck and the building below it when the roof covering is damaged or blown off becomes critical. One of the best ways to provide protection from water intrusion into the structure is to install a self-adhering underlayment directly to the roof sheathing. After all, these products are designed and tested to be adhered directly to wood sheathing, not to #30 felt or synthetic underlayments.

Let’s jump into the advantages and disadvantages of adhering the underlayment directly to the deck. The table below was developed in cooperation with multiple industry stakeholders, including a Florida code enforcement agency. I’m sure we didn’t capture everything, but it’s a fairly comprehensive list.

As the table below indicates, the advantages far outweigh the disadvantages. In fact, a couple of the suggested “disadvantages” essentially conflict with each other: if the products being installed on a deck that isn’t 100 percent clean and dry was really an issue (and how often is “dry” even possible in South Florida?), they wouldn’t also be difficult or impossible to remove when reroofing. Read more.

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