The first distinction most recovery discussions skip
An exposed weathering panel and a structural metal deck are not interchangeable substrates. A deck often supports another roof assembly; an exposed panel is itself part of the weathering surface. Treating both as simply “metal” can hide different attachment and preparation questions.
SPFA-104, 2023 edition distinguishes structural metal decks from sloped roof panels and separately discusses fluted-deck preparation. That distinction is the starting point—not a blanket endorsement of spraying every metal surface. This guide concerns exterior roofing, not interior metal-building insulation.
Three illustrative conditions, three different investigations
| Observed condition | What it does not prove | Next evidence needed |
|---|---|---|
| Intact-looking painted panels with isolated surface rust | That the remaining section, coating adhesion, or attachment is adequate | Condition review, coating identification, preparation/adhesion evaluation, and attachment assessment |
| Perforation or visibly deteriorated metal | That foam or primer can replace missing structural capacity | Qualified assessment of replacement/repair and support conditions before recovery |
| Standing seams, moving joints, or existing expansion joints | That a continuous foam surface can safely immobilize every joint | A movement-compatible, manufacturer-reviewed detail and design review where needed |
These scenarios are an owner’s decision aid, not photographs or findings from Score projects. They deliberately stop before a repair prescription: panel type, corrosion extent, load paths, and movement cannot be established from a generic article.
Adhesion is only one link in the load path
The IBHS/RICOWI guide, section 1.4.2, explains that recovery-system uplift depends on the existing covering’s securement and the deck’s connection to the frame. Strong foam adhesion cannot establish the adequacy of hidden fasteners or corroded supports. A surface pull test answers a narrower question than a whole-assembly design review.
Make the proposal show the unresolved conditions
Request a roof-area map that differentiates retained panels, metal repairs, coating removal or preparation, transitions, and joints requiring special details. Pair each unresolved condition with a responsible reviewer and a decision date. An allowance for metal repairs should state its quantity basis and authorization process, rather than treating all unseen deterioration as included.
SPFA-104 also treats expansion joints separately and notes that structural design analysis may be necessary. “Seamless” should describe an appropriate roofing surface, not an excuse to disregard building movement.
A useful stop/go question
Ask: “What evidence establishes that this metal assembly can remain beneath the proposed roof?” If the answer is only “the foam sticks,” the assessment is incomplete. Continue with the broader existing-roof eligibility guide, then discuss a commercial roof assessment and the proposed SPF roofing system.