The Problem
The owners of a 1964 ranch in East Mundelein called after noticing a musty smell near the fireplace after rain. On roof inspection, the chimney crown showed a full transverse crack running the width of the cap, and the south edge had partially separated from the brick face - a gap wide enough for direct water entry into the flue seat.
Stack joints above the roofline averaged 5/8-inch recess on the south and west faces. The original 1964 mortar, a gray Type N, had carbonated to the point of crumbling at the joint surface. Several joints near the top three courses had lost mortar entirely.
Debris at the firebox floor, combined with the crown failure, made a liner inspection necessary before other work could begin.
Our Solution
We demolished the failed crown in sections using hand chisels and a rotary hammer, working carefully at the crown-to-brick interface to protect the top course. The crown bed was cleaned and the uppermost joints raked and repacked before forming.
The replacement crown was poured in two lifts using a fiber-reinforced mix, formed with a 1/4-inch-per-foot outward slope and a 1.5-inch overhang past the brick face on all four sides. Once cured, we applied an elastomeric seal coat over the full crown surface and the top two brick courses to create a continuous water barrier at the most vulnerable transition.
Stack repointing used Type N mortar batched against a protected north-face joint below the roofline, where the original gray aggregate color had been least weathered. All joints above the roofline were ground to 3/4-inch depth, vacuumed, dampened, and packed in two lifts to a concave profile. Flue liner inspection from the cleanout access found no active cracking in the accessible clay tile sections. Flashing step joints were resealed with polyurethane.
The Result
The musty smell stopped after the first full wet season following the work. The replacement crown shows no cracking at 90 days. Stack joint recess is now uniform at finished concave depth. The homeowners have a written record of the liner inspection for future reference.
Related: Chimney Repair Services | Mundelein Service Area
