The Problem

A property owner in Downtown Waukegan contacted us about large sections of parging falling off the exposed foundation and below-grade walls of their 1932 commercial building on Genesee Street. Parging is the thin coat of mortar applied over masonry foundations to seal the surface and present a uniform face. On a building this age, the original parging has lived well past its typical service life.

The failure mode here was delamination: the parging had separated from the substrate in sheets rather than crumbling in place. Approximately 60 square feet had already fallen off, exposing the original brick and early concrete block below. The remaining parging showed hollow sections across most of the wall, confirmed by tapping with a hammer and hearing the drum sound rather than a solid return. Water had been getting behind the parging layer and the freeze-thaw cycle was finishing the job year over year.

Two diagonal cracks in the foundation wall itself, each roughly 14 inches long, also needed to be addressed before any resurfacing work.

Our Solution

We removed all remaining parging across the 180-square-foot problem area using hand chisels, taking care not to damage the underlying masonry. Any parging that sounded hollow was removed regardless of whether it had visibly failed yet; leaving hollow sections behind guarantees early re-failure of the new coat.

The two diagonal foundation cracks were routed to a uniform V-profile and packed with hydraulic cement, which sets in the presence of moisture and bonds strongly to the damp masonry typical of below-grade work on a building of this age. Both cracks were filled, consolidated, and allowed to cure fully before we proceeded.

The foundation surface was pre-dampened to control suction before application. The first scratch coat of Type S parging was applied at 3/8-inch thickness and cross-hatched while still workable to create a mechanical bond key for the second layer. After a 24-hour cure window, the finish coat was applied at 1/4-inch thickness and float-finished to a consistent texture. Type S is the correct specification for below-grade and foundation parging: its higher Portland content gives it the compressive strength and water resistance needed in ground-contact conditions.

The Result

The full parging system is reinstalled over a crack-free substrate. The two-coat method ensures the finish layer is fully bonded and will not delaminate the way the original single-coat application eventually did. The repaired section is color-consistent with the adjacent wall areas.

The property owner was advised that the above-grade brick on the building’s south facade shows mortar joint deterioration and should be assessed for tuckpointing in the next service cycle.

Frequently Asked Questions

question: “What causes parging to fall off in sheets rather than crumbling?” answer: “Sheet delamination usually means water got behind the parging layer and the bond between the parging and the substrate failed over time. Freeze-thaw cycling accelerates this process dramatically. A properly bonded, two-coat application over a pre-dampened substrate resists this failure mode.”
question: “Why does parging need two coats?” answer: “A single thick coat of parging is more prone to shrinkage cracking as it dries and is harder to bond fully to a rough masonry substrate. Two thinner coats, with the first scratched to create a bond key, produce a stronger, more flexible system. The scratch coat gets bonded to masonry; the finish coat gets bonded to the scratch coat.”
question: “Is hydraulic cement the right product for foundation cracks?” answer: “For active cracks in below-grade or damp masonry, hydraulic cement is a practical solution because it sets and bonds in the presence of moisture. For above-grade cracks in dry conditions, a stiffer mortar mix is typically used. Matching the repair material to the moisture environment matters for long-term performance.”