4101 N Mason Ave 2
This building has significantly more problems than most nearby buildings. A handful of unresolved issues. Worth a careful walk-through and pointed questions.
This building has 4 building violations (7y), above the Portage Park average of 0.7.
What's in the 4101 N Mason Ave 2 report
| Units | 4 |
|---|---|
| Year built | 1924 |
| Stories | — |
| Building area | 4,354 sq ft |
| Property class | 211 |
| PIN (Cook County parcel) | 13174140200000 |
Registered owner per Cook County Assessor records.
Landlord portfolio
Other Chicago properties this owner holds, with risk grades for each.
Unlock complete reportThe four-unit residential building at 4101 N Mason Ave 2 in Chicago's Portage Park neighborhood, owned by Hernan C Aguilar, has been part of the city's property records since its construction in 1924. The building's recent history shows significant concern, particularly with four outstanding complaint-driven building code violations from August 2019 that remain open and unresolved, which is particularly noteworthy given their age and potential impact on resident safety and comfort. The property has experienced a variety of 311 service requests over the past seven years, with the most recent activities in 2025-2026 primarily related to external matters such as tree planting and maintenance, parking code enforcement, and vehicle complaints. Notably, there was one significant concern in 2024 involving a vacant/abandoned building complaint and a building violation that were both closed, though the nature and resolution of these issues aren't specified in the available data. The building's total record shows 4 building violations and 7 service requests in the past seven years, with the owner also involved in 8 total service requests across two parcels. The presence of multiple open violations from 2019 and the cluster of service requests in 2024-2026 suggest potential ongoing maintenance and management challenges, though the recent nature of the tree-related requests indicates some level of property upkeep.
AI-generated · may contain errors · check the source data tables below
How 4101 N Mason Ave 2's risk score is calculated
We trained a model on 7 years of Chicago code enforcement data — building violations, 311 complaint history, environmental enforcement, and owner track records. It estimates the probability that the City of Chicago will find a code violation at this address in the next 12 months. Lower % = safer.
What the score means for you
Grade A–B — Low risk
City inspectors rarely find violations here. Strong maintenance history and a clean complaint record.
Grade C — Moderate risk
Some past violations or complaints on record. Worth asking the landlord about any open issues before signing.
Grade D–F — High risk
Elevated violation and complaint history. City inspectors have found issues here before and are statistically likely to again.
Out of 3910 buildings in this neighborhood, 3519 are predicted to be safer.
violation
likely
What's driving this score
The data points that most influenced this building's risk rating — ranked by the weight the model placed on each one.
4101 N Mason Ave 2 apartment reviews
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4101 N Mason Ave 2 event timeline
Building violations, environmental complaints and enforcement, permits, scofflaw listings, and 311 calls — most recent records in order.
See all 9 events
Full history back to 2019 — violations, complaints, permits, and 311 calls.
Unlock complete timelineFull data for 4101 N Mason Ave 2 apartments
Chicago public datasets for this parcel — building violations, permits, 311 calls, environmental complaints and enforcement, scofflaw listings, and vacant building registrations.
What this is
Violations issued by the City of Chicago Department of Buildings against this parcel.
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What this is
Violations issued for failure to register or maintain a vacant or abandoned building.
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What this is
Building permits issued by the City of Chicago for new construction, alterations, and repairs at this parcel.
| Permit # | Issued | Status | Description |
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What this is
Chicago 311 service requests recorded at this parcel — maintenance complaints and quality-of-life requests.
| SR # | Created | Type | Department | Status |
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What this is
Environmental complaints filed about this property with the City of Chicago.
| Complaint # | Date | Type | Inspector | Resolution | Resolved |
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What this is
Formal environmental enforcement cases brought against this property.
| Case # | Date | Type | Violation | Disposition | Status | Fine |
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