Multifamily Alteration
Apartment + condo alterations, renovations, + envelope work.
2.9M permits classified across 23 metros
Browse multifamily alteration permits in New York City →What it covers
Multifamily alteration permits cover changes to existing apartment and condo buildings — unit-level reconfigurations, common-area overhauls, structural retrofits, roof replacements, and substantial systems work. The highest-volume multifamily segment in most US metros because turnover + aging-stock maintenance dominate filings against existing buildings.
How a permit lands in Multifamily Alteration.
Every silver permit flows through a two-stage classifier. The deterministic stage maps the structured signals — work_class, the normalized permit type, and the building sub-type — into the segment vocabulary where the mapping is unambiguous. The machine-learning stage handles the cases that aren't direct lookups: multi-vocab permit-type strings, ambiguous occupancy spans, and jurisdictions that bundle categories. The segment is the classifier's output, the same axis across every metro — so multifamily_alteration means the same thing in NYC as in LA even though the upstream jurisdictions emit completely different raw permit-type strings.
When the signal genuinely isn't there, we say so. A row with no assignable segment degrades honestly — to its work-nature, then to its raw source type, and only to “Unclassified” when truly nothing is known. We never guess a segment to fill a gap; an honest Unclassified is the floor, and field-level data-quality flags surface when the classifier had low confidence. That restraint is the point — the classification is only worth selling on if the “don't know” is honest.
Multifamily Alteration by metro
Where multifamily alteration permits are classified today, ranked by volume. Metros with recent activity link straight into the live browse; the rest show their all-time classified count.
- New York City →2.4M
- San Francisco →287K
- Los Angeles →145K
- Columbus →28K
- Austin →7,679
- Cincinnati →5,151
- Raleigh3,458
- Boston →3,170
- Fort Worth2,165
- Norfolk1,125
- Atlanta860
- Philadelphia →851
- Portland350
- Memphis341
- Baltimore →221
- Charlotte211
- Tucson172
- San Jose →143
- Seattle129
- Washington, DC7
- Phoenix2
- Chicago1
- Sacramento1
Recent multifamily alteration permits
Real permits classified into Multifamily Alteration in the last 30 days.
- 1257 S KIRKMAN RDAlteration / Residential$13K2026-07-02Orlando
- 1505 S KIRKMAN RDAlteration / Residential$13K2026-07-02Orlando
- 80-11 90 AVENUEAlteration / Residential$611K2026-07-01New York City
- 80-11 90 AVENUEAlteration / Residential$611K2026-07-01New York City
- 80-11 90 AVENUEAlteration / Residential$611K2026-07-01New York City
- 80-11 90 AVENUEAlteration / Residential$611K2026-07-01New York City
Who tracks Multifamily Alteration.
Multifamily Alteration is a sales-intelligence segment for suppliers and reps targeting multifamily developers and general contractors. Filter it by metro, rank the contractors pulling these permits, and see the projects worth selling into — the same way across every covered market.