The important question is where the load goes
The IBHS/RICOWI SPF guide, section 1.4.2, explains that recovery performance depends on the existing roof covering’s securement to the deck and the deck’s securement to the frame. A strongly adhered upper layer does not eliminate the connections below it.
Think of the load path as foam → substrate or retained covering → attachment → deck → structure. Each arrow is a question for the project team. This is an explanation of connected components, not a claim that every assembly has the same layers.
A practical mismatch example
Illustrative scenario: a submittal describes SPF bonded directly to structural concrete. The actual proposal places SPF over mechanically attached cover board above retained roofing. Even if the foam product is identical, the attachment path is different. The concrete-based evidence cannot simply be carried over without an applicable approval or qualified design determination.
The same IBHS guide distinguishes direct-deck pull testing from uplift behaviour involving mechanically attached substrates. This is why a high adhesion number should not be converted into an advertised building wind-speed rating.
The approval-to-project cross-check
| Record | Match required | Question if different |
|---|---|---|
| Approval identification and revision | Applicable document and scope | Is this current evidence for the proposed system? |
| Deck and substrate | Actual materials and configuration | Does the approval cover this retained assembly? |
| Attachment | Applicable fasteners, adhesive, spacing, and support conditions | Who resolves substitutions or unknown existing attachment? |
| Design requirements | Building-specific zones and loads | Has the responsible designer checked the project, not only the product? |
| Edges and transitions | Compatible project details | Are perimeter interfaces part of the reviewed scope? |
Keep different numbers in their proper role
Wind speed, pressure resistance, adhesive strength, and a test classification are not interchangeable labels. Converting among them requires applicable design methods, factors, geometry, and assumptions. This article intentionally supplies no universal conversion or NY/NJ design pressure.
The IBHS guide identifies FM 4474 and UL 580 among relevant testing routes and points to evaluation agencies. It is industry guidance, not the current code determination for a particular address. Obtain the actual applicable assembly document and project design review.
Warranty wording is another reason to resolve design responsibility
The Gaco sample system warranty lists inaccurate wind-uplift/design-load calculations among its general exclusions. That does not describe every warranty, but it shows why purchasing a long warranty is not a substitute for an adequately documented design.
For recovery, start with existing-roof eligibility and discuss the proposed SPF system in a commercial roofing assessment. For damage already sustained, use the separate damage-response guide.