There's a phrase in the historic preservation world: "do no harm." It sounds simple, but it's routinely violated in masonry repair. The most common form of harm on historic brick buildings isn't neglect — it's well-intentioned repair done with the wrong materials. A contractor who repoints a 1920s brick building with Type S mortar hasn't fixed the problem. They've accelerated it.

Emerald Masonry LLC works on older and historic masonry throughout DuPage County, including Westmont and its surrounding communities. We specify repair materials based on the age and composition of the existing construction, not convenience or what's standard for modern work.

What Makes Historic Masonry Different

Buildings constructed before 1950 — and especially before 1930 — were built with fundamentally different materials than modern masonry:

Softer brick. Pre-war brick was typically fired at lower temperatures, producing units with higher porosity and lower compressive strength than modern brick. This isn't a defect — it's how the masonry was designed to perform. The softer brick absorbs and releases moisture slowly, and the mortar around it is designed to be even softer, so movement occurs in the joints rather than cracking the units.

Lime-based mortar. Historic masonry used mortars with high lime content — sometimes pure lime putty, sometimes natural cement blends, occasionally early Portland cement mixes. These mortars are soft, flexible, and somewhat self-healing. They have a compressive strength of 500–1,000 psi, far below the 1,750+ psi of modern Type S mortar.

The compatibility principle. In masonry, mortar should always be softer than the brick. This allows the mortar joint — the expendable, replaceable element — to absorb movement and moisture damage rather than the brick unit, which is not expendable. When modern hard mortar is used to repoint soft historic brick, the mortar's rigidity forces movement into the brick, causing face spalling and cracking that destroys irreplaceable original material.

This is why historic masonry restoration requires a different mortar specification than standard commercial work.

What Historic Restoration Involves

Mortar Analysis and Specification

Before repointing any historic masonry, we assess the existing mortar composition. In the field, this means examining mortar hardness with a nail or chisel (hard mortar won't scratch; lime mortar will), checking the color and texture, and noting the joint profile. For critical or high-value projects, mortar analysis can be done in a laboratory to identify the exact lime/sand/cement ratio of the original mix.

The new mortar is then specified to match the original's strength class and composition. For pre-1930 construction, we typically use Type N or O mortars with significant lime content, or custom NHL (natural hydraulic lime) mixes for buildings that originally used natural cement. For mid-century construction (1930–1960), we assess case by case, as mortar composition varied widely during this period as Portland cement became more common.

Careful Joint Preparation

On historic masonry, joint removal requires hand tools or low-vibration power tools rather than aggressive saw cutting. The goal is to remove deteriorated mortar without damaging the soft brick arrises (edges). Chisels, oscillating tools, and specialized grout rakes are standard. Angle grinders with aggressive diamond wheels can chip and damage historic brick edges — we use them selectively if at all on pre-war construction.

Brick Replacement on Historic Buildings

When individual brick units must be replaced on an older Westmont building, matching requires more effort than modern work:

Period brick is typically smaller than modern standard (modular) brick — 2¼ inch height vs. today's 2¾ inch
Surface texture, color variation, and wire-cut vs. molded face profiles differ significantly between eras
Salvage brick from the same period is often the best source

We maintain relationships with salvage suppliers in the Chicago area and can source period-appropriate brick for older DuPage County properties. Getting the match right matters — visible patchwork on a historic facade affects property value, historic district eligibility, and overall appearance.

Westmont and DuPage County Historic Properties

Westmont's older building stock includes early 20th-century commercial buildings along Cass Avenue, institutional masonry (churches, schools) dating from the 1910s through 1950s, and established residential neighborhoods with brick homes that are now 70–100 years old.

DuPage County's climate is aggressive on historic masonry. The combination of significant freeze-thaw cycling and the brick softness typical of pre-war construction makes mortar compatibility especially critical. A well-maintained historic brick building with compatible repair mortar will outlast a modern building. One that's been repeatedly repointed with hard Portland cement mortar may have irreversible spalling damage within a few decades of that first bad repair.

Institutional Buildings

Churches, schools, and civic buildings in the Westmont area are among the most common projects we see for historic masonry restoration. These buildings were built to last — the original construction was quality work — but they've often been maintained by facilities teams or general contractors who didn't specialize in historic masonry. The result is frequently hard mortar over old soft joints, and spalling brick above those repointed areas.

Restoring an institutional building correctly means removing the incompatible repair mortar (a delicate process), assessing the brick condition underneath, replacing any units that have spalled, and repointing with a compatible mix. Done right, this work extends the building's life by generations.

Frequently Asked Questions

How do I know if my Westmont building qualifies as "historic" for the purposes of masonry repair? "Historic" in our context means the masonry was built with lime-based or early Portland cement mortars — typically any construction from before the mid-1950s. It doesn't require formal historic designation. The relevant question is material compatibility, not listing status. If your building predates 1955, assume it needs a softer mortar than standard commercial work.

Can the wrong mortar really damage historic brick that much? Yes. We've documented cases where a single repointing with hard mortar caused brick face spalling within 3–5 years — damage that didn't exist before the repair. The spalling is irreversible. Once the face of a historic brick is gone, the unit has to be replaced, and replacement with a matching historic unit is expensive and sometimes impossible.

Is historic masonry restoration more expensive than standard tuckpointing? Yes, typically by 25–40%. Mortar analysis or specification, hand tool joint removal, careful brick matching, and curing protocols all take more time than standard commercial work. But the cost of doing it wrong — repeated repairs, brick replacement, potential loss of historic status or property value — is far higher. Our $5,000 minimum applies. We provide free written estimates.

Do you work with historic preservation consultants or architects? Yes. For projects involving formal historic review (SHPO review, local historic district approval, or National Register properties), we can work alongside preservation architects and consultants and provide the documentation they need regarding materials and methods.

Schedule a Historic Masonry Assessment in Westmont

If your Westmont or DuPage County property is an older building showing signs of masonry deterioration, get an assessment from a contractor who understands the material compatibility issues.

Call Emerald Masonry LLC at (309) 323-9959 or request a free on-site estimate.

Also see: Masonry Restoration | Tuckpointing & Repointing | Brick Repair

Historic Masonry Restoration in Westmont, IL — Preservation-Grade Repair for Older Buildings