Roofing Sealant

Flexible Weatherproofing

Roofing sealant is a flexible, weather-resistant compound used to seal joints, fasteners, and transitions on the roof surface, maintaining its elasticity after curing to accommodate the thermal expansion and contraction that roof components undergo. Unlike rigid roof cement, sealant remains pliable, making it the preferred product for sealing joints that move with temperature changes. Roofing sealants come in polyurethane, silicone, and modified polymer formulations, each suited to different applications.

Sealant is a detail item that appears throughout the roof but is easy to overlook in an estimate.

Where Sealant Is Applied

Sealant is used at exposed fastener heads on metal roofing, around pipe boot flanges, at flashing terminations, at skylight curb joints, and at any point where two different materials or planes meet. On metal roofs in particular, every exposed fastener gets a bead of sealant to prevent water intrusion around the screw penetration. The sealant must be compatible with the roofing material. Silicone sealant, for example, does not adhere well to asphalt products, while polyurethane sealant works with most materials.

Using the wrong sealant type is a common installation error that leads to premature failure and leaks.

Sealant in the Estimate

For standard installations, sealant is included in the labor and material component of the primary line items. When the repair scope involves extensive sealant work, such as resealing all pipe boots, resealing all exposed fasteners on a metal roof, or sealing all flashing terminations on a repair rather than replacement, a separate line item may be appropriate. Document the extent of sealant work with photos to justify the additional item if the reviewer questions it.