Masonry Repair - Niles, IL

Masonry Repair - 1962 Lintel Rust and Foundation Parging

October 20, 2025 | near Oakton Street

Before

After

Location Niles, IL

Service Masonry Repair

Scope 2 lintels repaired, 48 linear feet of foundation parging restored

Mortar Type Type S parging mix

Duration 4 days

Building 1962 lintel and foundation parging

The Problem

A homeowner in North Niles called after noticing two distinct problems during a spring inspection. First, horizontal cracks had opened in the brick course immediately above both front windows - a stair-step crack pattern running along the mortar joint just above the window frame. Second, large sections of the foundation parging on the east and north sides of the house had popped off, leaving bare concrete block exposed at grade level where snowmelt pools in winter.

The window cracks were caused by corroded steel lintels. Both lintels had rusted significantly, and the rust expansion had fractured the mortar bed and begun to push the brick above each opening outward. The parging failure was straightforward deterioration - the original 1962 application had reached the end of its service life and was no longer bonding to the block substrate.

Our Solution

For the lintels, we carefully removed the brick course above each opening to expose the full lintel. Both steel lintels were wire-brushed clean of rust, treated with a penetrating rust converter, and coated with a zinc-rich primer before reinstallation. The brick above each lintel was reset in Type S mortar and the horizontal joint was re-established at the correct depth to allow any future water to drain forward and out rather than sit against the steel.

For the foundation, we removed all hollow and delaminated parging sections with a cold chisel - roughly 60 percent of the original surface. The exposed block was cleaned with a masonry brush and dampened before the new parging was applied. We used a Type S cement and lime parging mix applied in two coats: a scratch coat keyed into the block surface, allowed to cure 24 hours, then a finish coat troweled smooth and feathered at the top edge to shed water away from the wall.

The Result

The lintel repair stopped the expansion cracking mechanism. The window openings above are stable and the brick courses are plumb. The restored parging seals 48 linear feet of foundation that was actively wicking ground moisture into the block. The north and east walls are now protected through winter freeze cycles.

Questions About This Project

What causes steel lintels to crack the brick above windows?

Steel lintels are embedded in the brick above door and window openings to carry the load of the masonry above. When water enters the joint between the lintel and the brick course above it, the steel begins to rust. Rust expands at roughly 6 to 8 times the volume of the original steel. That expansion exerts outward pressure on the brick above and below the lintel, cracking the mortar bed and eventually the brick face itself. The pattern shows up as horizontal cracks just above the window opening.

What is foundation parging and why does it fail?

Parging is a thin coat of mortar applied over a concrete block foundation to seal the surface and protect it from water infiltration. Original parging from the 1960s was typically a lime and sand mix applied by hand. Over time, small cracks form from freeze-thaw cycling, and water enters. Once water gets behind the parging layer, it expands during freeze cycles and pops sections of the parging off. Bare block is then exposed directly to ground-level moisture and snowmelt.

Can you parge over existing deteriorated parging, or does it have to come off first?

Any loose or hollow-sounding parging has to come off first. Applying new parging over failing sections produces a weak bond that fails again quickly. We use a masonry hammer to test the entire surface - a dull thud indicates hollow spots that need removal. Solid sections can be prepared and overcoated. Attempting to parge over deteriorated material is a common shortcut that adds a few years at best before the cycle repeats.