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Masonry construction presents a different flashing problem than a typical wood-framed wall, because brick, block, and stone are porous materials that move at a different rate and in a different way than the roofing or siding that meets them. Where a roof surface terminates against a masonry parapet, chimney, or wall, the counterflashing that laps over the base flashing has to be anchored into the masonry itself, and two methods dominate that detail: reglets and surface-mounted flashing.
A reglet is a horizontal slot cut or cast into a mortar joint, into which the top edge of a metal counterflashing strip is inserted and then secured with a lead wedge, sealant, or both. Because the reglet places the counterflashing behind the face of the masonry, it sheds water without relying on a surface bead of sealant to do the primary work of keeping the wall watertight. This is generally regarded within the roofing and masonry trades as the more durable long-term detail, and it appears frequently on commercial buildings, brick chimneys, and older masonry parapets, since cutting a reglet into existing masonry is a routine repair-and-reroofing task.
Surface-mounted counterflashing takes a different approach: a metal strip is screwed or nailed directly to the face of the masonry, usually with a termination bar, and the joint is then sealed with an elastomeric sealant. This method is faster and less expensive to install, particularly where cutting into existing masonry would be impractical or where the wall assembly is not built of solid units that accept a reglet cleanly. Its long-term performance depends entirely on the sealant joint, which is exposed to direct sun, moisture, and the freeze-thaw cycling that Minnesota winters produce in abundance. Sealant at a surface-mounted termination bar is a maintenance item that most manufacturers and roofing associations, including guidance published by the National Roofing Contractors Association, expect building owners to inspect and renew periodically.
When a chimney or parapet has sustained wind or hail exposure, the condition of both the reglet and the sealant line becomes relevant to documenting roof and flashing damage, since displaced mortar, cracked sealant, or a counterflashing strip pulled loose from its reglet can each allow water to track behind the wall assembly. Differentiating a sealant joint that has simply reached the end of its expected service life from one that failed because of a specific storm event again requires careful observation of the physical evidence at the joint itself. Coverage determinations that follow from that evidence rest with the policy and the parties to it.
Chimney crowns and caps add a related layer to this discussion, since the crown, the sloped concrete or mortar cap covering the top of a masonry chimney, is itself subject to freeze-thaw cracking that can independently allow water into the flue liner and surrounding masonry, separate from anything happening at the roof-line counterflashing below. Differential movement between a masonry chimney, which does not expand and contract at the same rate as the surrounding wood-framed roof structure, is one reason step flashing along a sloped roof-to-chimney intersection is built from individual overlapping pieces rather than one continuous strip, allowing each course to move slightly without breaking the water seal. Where an older chimney has settled or where mortar joints have deteriorated to the point that a reglet no longer holds a counterflashing strip securely, rebuilding a portion of the masonry itself sometimes becomes part of a flashing repair, a scope question that a mason and a roofer often need to coordinate on jointly.
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. Contact Appraisal Resolution.