Alligatoring and crazing are common forms of surface cracking that can appear on aging commercial roofing systems, particularly asphalt-based roofs. Although they may initially look like minor cosmetic defects, widespread cracking can allow moisture to penetrate the roofing assembly and contribute to leaks, deterioration, and shortened roof life. Addressing these problems early can help building owners avoid more extensive repairs or premature roof replacement.
What Is Alligatoring?
Alligatoring describes a network of interconnected cracks that resembles an alligator’s skin. It is frequently associated with older smooth-surface asphalt roofing and can develop as the roofing material ages, loses flexibility, shrinks, or experiences repeated thermal movement.
Alligatoring may occur when the surface cannot adequately accommodate expansion and contraction caused by changing temperatures. Long-term ultraviolet exposure, weathering, inadequate material performance, and aging can also contribute to surface cracking.
If alligatoring is extensive, simply applying another layer of coating over the cracks may not provide a durable solution. The roofing contractor should first determine whether the underlying membrane remains structurally sound.
What Is Crazing?
Crazing refers to a fine network of shallow surface cracks. Unlike larger splits or open membrane failures, crazing can initially be limited to the upper surface of a roof coating or asphaltic material.
However, extensive crazing should not be ignored. Continued weather exposure can cause small cracks to become wider or deeper, potentially allowing water to reach underlying roofing components.
How Are Alligatoring and Crazing Repaired?
The correct repair depends on the severity, extent, moisture condition, and overall condition of the roof system.
1. Inspect the Entire Roof
The first step is a professional roof inspection. The contractor should identify the extent of alligatoring or crazing and check for associated problems such as open cracks, blisters, splits, ponding water, wet insulation, damaged flashing, and deteriorated decking.
A roof that is substantially deteriorated or moisture-damaged may require replacement rather than a simple coating or surface repair.
2. Clean and Prepare the Surface
Before applying a restoration system, the roof surface needs to be properly prepared. Dirt, debris, loose material, and other contaminants can interfere with adhesion. Manufacturers commonly require asphaltic substrates to be clean and dry before liquid-applied roofing materials are installed.
Loose or damaged roofing materials should be removed or repaired so that the remaining surface provides a suitable substrate.
3. Repair Significant Cracks and Defects
Individual open cracks, splits, seams, and other membrane defects should be repaired using materials compatible with the existing roofing system. Simply covering an active structural defect with coating can result in premature failure.
For reroofing or restoration projects, existing defects should be addressed before the new roofing system is installed. Industry installation guidance also emphasizes replacing wet or damaged roofing materials and creating a smooth, clean, dry substrate before proceeding.
4. Use Reinforcement for Extensive Cracking
When alligatoring or cracking covers large areas but the existing roof is still suitable for restoration, a reinforced coating system may be considered. Polyester reinforcement fabric can be incorporated into elastomeric coating systems to strengthen heavily cracked or alligatored areas and distribute stresses from normal building movement.
The specific coating, primer, fabric, and application thickness should be selected according to the existing roof and manufacturer’s requirements.
5. Consider Roof Restoration or Replacement
A roof with limited surface crazing or localized alligatoring may be a candidate for repair and restoration. A structurally sound roof can sometimes receive a properly designed liquid-applied restoration system, extending its service life without complete removal.
However, widespread deterioration, saturated insulation, severe membrane cracking, or damaged decking may make commercial roof replacement the more appropriate long-term solution.
Preventing Future Alligatoring and Crazing
Regular commercial roof inspections and maintenance can help identify surface cracking before it develops into major membrane damage. Proper drainage is also important because standing water can accelerate deterioration. Building owners should address damaged areas promptly rather than allowing small cracks to remain exposed to Florida’s intense sun, heat, rain, and storms.
Final Answer
Alligatoring and crazing are addressed by first determining the condition of the existing roofing system, repairing significant defects, properly preparing the substrate, and then using a compatible repair, reinforced coating, restoration system, or replacement where necessary. Minor surface cracking may be manageable through restoration, while extensive cracking or underlying moisture damage may require more substantial corrective work.
For commercial properties, the best solution is not simply to cover visible cracks. A professional roofing assessment should determine the cause and extent of the damage and whether the existing roof is suitable for restoration or requires replacement.
Related Questions
- How do polycarbonate skylights degrade under Florida sun?
- How is a parking garage top deck waterproofed?
- What surface preparation is required for a fluid-applied restoration?
- Should a maintenance plan include minor repairs or inspection only?
- What are the signs of a deteriorating lightweight insulating concrete deck?
- What if my roof report shows minor damage?
- What causes “fishmouths” in TPO flashing and why are they a problem?
- What damage do bee and wasp nests cause in roof cavities?
- Can small blisters be ignored, or do they always require repair?
Commercial Roof Coatings & Restoration
