When comparing a roof recover with a new roof replacement, one important consideration is the fire rating of the finished roofing system. The key point is that a roof recover does not automatically receive the same fire classification as a completely new roof assembly. The final rating depends on the existing roof, the new roofing materials, the complete assembly, and the applicable code and testing requirements.
In Florida, roof assemblies and coverings are generally evaluated for external fire exposure using recognized testing standards such as ASTM E108 or UL 790. Roof systems may receive Class A, Class B, or Class C classifications, with Class A providing the highest level of external fire resistance.
What Is a Roof Recover?
A roof recover involves installing a new roofing layer over an existing roof covering rather than completely removing the existing roofing system. This approach can reduce tear-off work, disposal costs, and project disruption when the existing roof and substrate are suitable for recovery.
However, the existing roofing layers remain part of the overall roof assembly. That means the fire performance of the finished system can depend on both the existing assembly and the new roofing system.
For example, certain evaluated roofing systems permit new Class A, B, or C roof coverings to be installed over existing classified roof assemblies under specified conditions. In those circumstances, the resulting classification may be limited to the lower classification of the new and existing roof assemblies.
How Is a New Roof Different?
With a complete roof replacement, the existing roof covering is removed and the contractor can inspect and repair the deck and other components before installing the new system. The new roof can then be specified and tested as a complete assembly.
This gives the designer and building owner greater control over the components contributing to the roof’s fire performance. Depending on the roofing system, the assembly may include the roof deck, insulation, cover board, underlayment, membrane or shingles, and other components.
A new roof is therefore not automatically Class A simply because it is new. The entire assembly must meet the applicable fire-classification requirements and be installed according to the manufacturer’s tested or approved assembly.
Why the Existing Roof Matters During a Recover
A roof recover can create additional fire-rating considerations because the new roofing material is being installed over an existing assembly. The condition and classification of the existing roof may affect the final assembly.
Roofing manufacturers’ approval documents are particularly important. A system may have separate provisions for new construction and reroofing, specifying exactly which existing assemblies can remain underneath the new roof covering.
This is especially important for commercial buildings where the roof may contain multiple layers of membrane, insulation, cover boards, coatings, or previous repairs.
What Should Florida Building Owners Ask?
Before choosing a recover instead of a replacement, ask the roofing contractor:
- What is the existing roof’s fire classification?
- What fire classification does the proposed new system have?
- Has the complete recover assembly been tested or approved for the proposed application?
- Will the existing insulation and roof covering remain?
- Does the manufacturer’s approval specifically permit installation over the existing system?
- Are there local code, insurance, or project-specific requirements that require a particular classification?
Florida’s building regulations also distinguish between recovering and replacing an existing roof, and reroofing work must comply with applicable roofing requirements.
Recover vs. New Roof: The Bottom Line
A roof recover can achieve an acceptable fire classification, but its rating depends on the existing roof assembly and the specific new roofing system being installed. A completely new roof provides more opportunity to establish the fire performance of the entire assembly from the deck upward.
For Florida commercial properties, the safest approach is to verify the complete tested or approved roof assembly, rather than relying on the fire rating of the membrane or covering alone. A qualified commercial roofing contractor can evaluate the existing system, review manufacturer approvals, and determine whether a recover can satisfy the required fire classification or whether a complete replacement is the better solution.
Shieldline Roofing can help Florida commercial property owners evaluate existing roofing systems and determine whether a roof recover or complete replacement is appropriate based on the roof’s condition, assembly requirements, and applicable Florida code requirements.
Related Questions
- Do roof coatings carry their own fire ratings?
- Which insulation types affect the fire rating of the assembly?
- How does FM treat an existing roof during a recover?
- Do I need a permit for a roof recover in Florida?
- Is a roof recover always cheaper than a full tear-off in Florida?
- How is a gravel-surfaced BUR evaluated for coating or recover?
Commercial Roof Repair in Florida
