Two sources of technical guidance come up constantly in roofing and siding claims: the manufacturer’s published installation instructions for the specific product, and the building code adopted in the jurisdiction where the property sits. They serve related but distinct purposes, and understanding how they interact helps explain how an appraisal panel evaluates scope.
Building code sets a minimum baseline for safety and performance, covering things like fastening patterns, underlayment requirements in certain conditions, flashing at penetrations and walls, and structural considerations. Code is a legal requirement enforced by the local building authority, and it generally represents a floor, not necessarily the most protective or highest performing approach available.
Manufacturer installation instructions are product specific and are often more detailed than code on issues like fastener type, count, and placement for that particular shingle or siding product, starter course application, and required accessory components. Many codes, including common model codes, incorporate manufacturer instructions by reference for certain requirements, meaning the instructions effectively become part of the applicable code requirement for that installation. Warranty coverage from the manufacturer is also frequently tied to following those instructions, so a repair performed outside the instructions can affect whether a product warranty remains in effect, separate from any code question.
Where code and manufacturer instructions differ, the general working principle is that code represents the enforceable legal minimum, while manufacturer instructions can require more than code in order to protect the product warranty and expected performance. A repair that meets code but not the manufacturer’s specific instructions may still leave the warranty at risk, a separate concern from code compliance itself.
In an appraisal, both documents function as technical reference points. If a proposed scope of repair departs from either the applicable code or the manufacturer’s published instructions for the product being installed, that departure is relevant to whether the repair can reasonably be expected to perform and to remain under warranty. An appraiser or umpire weighing scope typically looks at both sources alongside the physical condition of the property, rather than treating either one in isolation. Neither document is treated as more important by default. A repair that satisfies code but ignores a specific manufacturer requirement, or one that follows a manufacturer preference beyond what code or the loss actually requires, both raise questions worth examining on their own facts.
Because code adoption and manufacturer instructions can both change over time, and because instructions differ by product line, confirming which code edition applied and which specific instructions covered the product in question, at the relevant time, is part of building a well documented scope of repair rather than relying on general industry practice alone.
This article is general education about how the appraisal process commonly works. It is not legal advice, and specific procedures can vary by state and policy.
Russ Lis is a working property insurance appraiser and umpire based in Minnesota, serving clients nationwide. His construction background supports an independent, evidence based opinion on scope and value in property insurance disputes. Contact Appraisal Resolution.