The bungalow belt runs from Rogers Park through Skokie, down Dempster through Morton Grove and Niles, and up through Lincolnwood. If you live in this corridor, your house was built between 1910 and 1935, and this post is specifically for you.
Tens of thousands of these one-and-a-half story brick homes were built across the metropolitan area. They were built to last, and most of them have. The problem is that they were built with a specific material system - soft common brick in lime-based mortar - and when someone comes along decades later and repoints the mortar with the wrong product, the brick starts failing. Slowly at first, then faster. It looks like weather damage. It is repair damage.
We drive these streets constantly. Here is what bungalow owners across the corridor need to understand before anyone touches their masonry.
What We See in Skokie Bungalows
Skokie has a dense concentration of 1920s common brick bungalows, many with the soft yellow or buff-toned brick characteristic of that era and that region’s clay sources. The mortar joints original are buff or cream, and the wall system was built around a principle that most people have never heard of: the mortar is supposed to be weaker than the brick.
That sounds backwards. It is not.
Masonry walls move. Temperature changes cause expansion and contraction. Soil settlement, moisture cycling, seasonal freeze-thaw cycling across the Great Lakes region - all of it creates stress in the wall. In the original system, that stress travels through the path of least resistance: the mortar joint. The joint flexes, slowly erodes, and eventually requires repointing. That is the expected maintenance cycle. The brick is protected because the joint absorbs the stress.
The lime-based mortar used on Skokie and Morton Grove bungalows has a minimum compressive strength well below that of the brick around it. Type O mortar runs about 350 PSI; original lime putty mortar may be softer still. That differential is intentional.
What we see most commonly on these houses: a repointing job done sometime in the 1980s or 1990s with Portland cement mortar. Type S mortar carries a minimum compressive strength of 1,800 PSI per ASTM C270 - far harder than the original brick. When the wall moves, stress can no longer travel through the mortar. It transfers into the brick face. The brick starts spalling. Fine crazing first, then thin flakes, then concave depressions where the face has fractured entirely.
Spring is when this damage becomes most visible. Brick that absorbed water through deteriorated original mortar and through the hard-mortar-to-brick interface froze and thawed through the winter. In April, you see the result.
The spalling is irreversible on damaged brick. The face cannot be restored. Options are limited to living with the appearance or replacing affected brick - a costly project that never produces a perfect color match.
For a detailed explanation of spalling mechanisms and how to identify the cause, see What Causes Brick Spalling and How to Prevent It.
The Lincolnwood Variation
Lincolnwood sits at the edge of the bungalow belt where the housing stock transitions. You have standard one-and-a-half story bungalows alongside two-flats and a few early six-flats, all from roughly the same construction period. Different floor counts produce different stress patterns on the masonry.
On a standard bungalow, the primary stress on the exterior wall comes from temperature cycling and soil settlement - relatively modest loads. On a two-flat or three-flat, the masonry carries more vertical load from the additional floors, and differential settlement between sections of the building can open diagonal cracks through the brick and mortar in patterns rarely seen on single-story structures.
On Lincolnwood two-flats, we pay particular attention to stair-step crack patterns in mortar joints - diagonal cracks following the joint lines at about 45 degrees. This is a classic settlement signature. It is not necessarily a structural emergency, but it needs proper assessment and appropriate repair, not just mortar fill. For guidance on reading these patterns, see Stair-Step Cracks in Brick: What They Mean.
The brick in this area was sometimes sourced differently than Skokie material. Some Lincolnwood construction used harder brick, some used the same soft common material. You cannot assume from the street. Assessment before any repointing is essential.
Niles and Morton Grove
Slightly later construction than the core Skokie stock - some of it from the late 1920s into the mid-1930s, and in a few pockets through the early 1940s. Slightly harder brick in some cases, but still overwhelmingly soft common brick with original lime mortar, and still showing the same damage patterns where Portland cement repointing has been done.
What distinguishes this area is the prevalence of lintel rust. Steel lintels over window and door openings on Niles and Morton Grove bungalows are approaching 100 years old. Corrosion is not just possible - it is likely. Corroding steel expands, cracking the mortar directly above the lintel and eventually cracking or displacing the brick above it.
Walk along any street in Morton Grove and look above the window openings. Horizontal cracking in the mortar joint directly above a window, rust staining on the brick face below, or a slight bulge in the brick courses above the opening - those are the lintel rust signatures. We see them constantly in this area.
This is distinct from the mortar compatibility problem but often appears on the same houses. A Niles bungalow from 1928 may have both: incompatible repointing from 30 years ago causing spalling at joint edges, and original lintels now showing corrosion symptoms above two or three window openings.
Also common in Morton Grove and Des Plaines: foundation transition problems. The transition between the above-grade common brick and the below-grade foundation masonry is a chronic water entry point. Check the parging coat on the foundation exterior for cracks or delamination. Efflorescence streaking below the water table line tells you water is getting through at this transition. Des Plaines homes near O’Hare also develop mortar joint cracking from ground vibration at a rate that is higher than most other suburbs in the corridor - a site-specific factor worth noting when assessing crack patterns.
For what efflorescence tells you and how to read it, see Efflorescence and White Staining in Spring.
Waukegan and the Northern Corridor
Waukegan extends the bungalow belt north into Lake County with a housing stock that shares most of the same construction characteristics - 1920s and 1930s soft common brick, original lime mortar - but sees higher moisture exposure from proximity to Lake Michigan. The lake effect produces more freeze-thaw cycling on the north and east elevations of Waukegan homes than the same homes would experience in the inland suburbs. Mortar joint deterioration on north-facing walls in Waukegan often runs 10 to 15 years ahead of the south elevation on the same house.
The practical implication: assess all four elevations independently. A Waukegan bungalow may have original lime mortar in good condition on the south and west, and joints requiring repointing on the north and east. Treating the building as a unit produces overwork on sound areas and underwork on compromised ones.
How to Read the Existing Mortar Before Anyone Touches It
The first thing we do on any bungalow assessment is read the existing mortar. You can do a basic version of this yourself.
Color: Original lime mortar is typically buff, cream, or light gray. It varies across the wall because original batches mixed at different times were not perfectly uniform. Repointing with Portland cement mortar usually looks noticeably different - grayer, more uniform, and harder looking.
Scratch test: Run a key or a nail along a clean joint face. Original lime mortar crumbles with light pressure. Portland cement mortar resists scratching firmly. If you feel the difference between two sections of the same wall, you can identify where the original material is and where someone repointed with a harder mix.
Weathering depth: Original lime mortar on an unrepaired wall weathers back naturally over decades, often 1/4 to 3/8 inch from the brick face. Portland cement repointing from 20 years ago may be slightly recessed from weathering but will look distinctly different in texture and color from the original sections.
BIA Technical Note 7B requires mortar removal to a minimum 3/4-inch depth before repointing. On soft common brick, hand chisels and a narrow mortar raking tool are the preferred removal method - power grinders can vibrate and chip the soft brick edges. On these houses, the masonry professional performing a proper assessment will compare mortar hardness directly to brick hardness and check the extent of any existing spalling before specifying a repair approach.
The Correct Repair Specification
Lime-based repointing uses a mortar softer than the brick it contacts. Three common specifications for bungalow work, per BIA Technical Note 8 and NPS Preservation Brief 2:
Type N mortar: Portland cement, lime, and sand blend. Minimum compressive strength of 750 PSI per ASTM C270. Appropriate for above-grade work where some compatibility with soft brick is needed.
Type O mortar: Higher lime-to-cement ratio. Minimum compressive strength of 350 PSI. Better compatibility with very soft brick. Less commonly stocked but available from masonry suppliers.
Lime putty mortar: Pure lime putty and sand, no Portland cement. Most historically compatible option. Very low compressive strength, high flexibility. Requires longer curing management - lime cures through carbonation rather than hydration, so moisture management during the first week of cure matters.
The right specification depends on the specific brick, the location on the building, and the condition of the existing wall. A mason experienced with historic masonry matches the new mortar to the existing system. A mason accustomed to commercial work applies whatever is convenient.
For more on why mortar color and composition matching matters beyond aesthetics, see The Importance of Mortar Color Matching in Tuckpointing.
What Category Is Your Home In?
For bungalows across Skokie, Niles, Morton Grove, and Lincolnwood, the state of previous repairs determines urgency and approach:
Original lime mortar in good condition: Monitor annually. Repointing becomes necessary when joints are recessed more than 1/4 inch, crumbling, or missing.
Previous Portland cement repointing with no visible spalling: Assess carefully. The mix may have been moderate enough to avoid causing damage so far, or damage may be developing under the surface. A professional assessment distinguishes between these.
Previous Portland cement repointing with spalling at joint edges: The most common problem scenario on these streets. The incompatible mortar needs to come out. Damaged brick must be assessed. Replacement work is done with a compatible specification.
Previous lime mortar repointing: Best scenario. Assess joint condition, repoint with matching material where needed.
A spring inspection identifies which category you are in. See our spring masonry inspection checklist for what to look for. For a full picture of how historic masonry systems differ from modern construction - and why the rules on pre-1920 brick homes change entirely - read our guide to historic masonry restoration across Chicagoland.
Scheduling
Tuckpointing and brick repair on a Chicago bungalow is planned maintenance, not emergency response - when you catch it at the mortar joint stage. It becomes a more complicated project when brick replacement is required or when water has reached the interior. Spring is the right time to assess because winter damage is fully visible and the temperature window for mortar work is opening.
Spring and early summer are the best seasons for mortar work in Illinois. If you are seeing crumbling mortar, spalling brick, or efflorescence on your bungalow in Evanston, Wilmette, or anywhere along the northwest suburban corridor, call (847) 713-1648 or contact us online to schedule a free assessment. We work with historic restoration specifications and carry lime-compatible mortar for the bungalow-era housing stock across the North Shore and northwest suburbs.