Reroofing a commercial building with an existing gravel-surfaced built-up roof (BUR) requires careful attention to the applicable building code, roof condition, structural capacity, drainage, wind resistance, and the installation requirements of the new roofing system. In Florida, these requirements are especially important because commercial roofs must withstand high wind loads and severe weather conditions.
Under the Florida Building Code (FBC), reroofing work must generally comply with the applicable roofing provisions of Chapter 15 of the Building Code and the requirements governing existing buildings. The Florida Building Commission identifies the 2026 Florida Building Code as the current ninth edition, while the eighth edition (2023) and its supplements remain important references for projects permitted under those provisions.
1. Inspect the Existing Gravel-Surfaced BUR
Before installing a new roofing system, the existing gravel-surfaced built-up roof should be thoroughly inspected. The inspection should identify moisture intrusion, wet insulation, deteriorated membrane, loose gravel, blisters, damaged flashing, substrate problems, and structural deficiencies.
The code does not permit a new roof covering to simply be installed over an existing roof when the existing roof is water-soaked or deteriorated to the point that it cannot serve as an adequate base for the new roofing system.
Moisture surveys and core cuts may therefore be appropriate when determining whether the existing BUR is suitable for a roof recover.
2. Determine Whether a Roof Recover Is Allowed
A roof recover involves installing a new roofing system over an existing roof rather than removing the existing assembly down to the structural deck. For an existing gravel-surfaced BUR, a recover may be possible when the existing roof meets the applicable code and the requirements of the new roofing system.
However, the Florida Building Code requires removal of existing roof coverings down to the roof deck in several circumstances. These include situations where the existing roof is deteriorated or water-soaked, where the existing roof has two or more applications of roof covering, where blisters are present unless properly repaired, or where the existing roof is being used to attach the new roof system but cannot satisfy the applicable securement requirements.
3. Address the Gravel Surface Properly
Gravel on an existing BUR cannot simply be ignored during reroofing. Loose aggregate can interfere with adhesion, mechanical attachment, and surface preparation. Depending on the selected roofing system, the existing gravel may need to be removed, embedded, brushed, spudded, vacuumed, or otherwise prepared according to the approved roofing assembly.
Florida-approved roofing assemblies specifically recognize existing gravel-surfaced asphaltic BUR as a possible substrate for certain reroofing applications when the surface has been properly prepared.
The exact preparation method should follow the approved assembly and manufacturer’s installation requirements rather than relying on a generic roofing procedure.
4. Verify Structural and Wind Requirements
The existing roof structure must be capable of supporting the new roofing system, construction materials, workers, and equipment. Florida code specifically requires structural roof components to support the roof-covering system and installation loads.
Wind-uplift resistance is particularly important for Florida commercial buildings. The proposed roofing assembly should have the required product approval and design pressure resistance for the building’s location and exposure. In High-Velocity Hurricane Zones (HVHZ), additional testing and installation requirements may apply.
5. Check Drainage, Flashing, and Penetrations
Reroofing should also address existing drainage systems, roof edges, penetrations, curbs, drains, scuppers, and flashing. Existing drainage should not be compromised by adding another roof layer.
Positive drainage remains an important consideration for low-slope commercial roofs. Flashings and edge details should be reconstructed or installed according to the approved roofing system and manufacturer’s instructions.
6. Follow Florida Product Approval Requirements
Commercial roofing products and assemblies used in Florida may need to comply with Florida Product Approval requirements or applicable local approval procedures. The roofing contractor should use an approved assembly appropriate for the building, roof deck, attachment method, and design pressures.
Final Answer
For an existing gravel-surfaced built-up roof, the key code requirement is not simply whether gravel is present, but whether the existing roof is structurally sound, dry, adequately attached, and suitable as a base for the proposed reroofing system. If the BUR is deteriorated, water-soaked, has multiple existing roof layers, or cannot satisfy the securement requirements of the new system, a tear-off to the roof deck may be required. A professional roof inspection, moisture assessment, code review, and verification of the proposed Florida-approved roofing assembly should be completed before reroofing begins.
For Florida commercial property owners, working with an experienced commercial roofing contractor can help ensure the reroofing project satisfies applicable Florida Building Code, wind-uplift, product approval, drainage, and installation requirements.
Related Questions
- What are the code requirements for replacing deteriorated deck sections?
- What does FBC Section 1512 require when re-covering an existing low-slope roof?
- Can gypsum roof decks still be reroofed in Florida?
- Should rooftop ballast gravel be removed in high-wind zones?
- How does the code define “roof repair” versus “roof replacement” versus “roof recover”?
- Where can I find the official 2026 Florida Building Code documents?
Commercial Roof Maintenance & Preventative Maintenance Programs in Florida
