Boston Building Demolition Analysis

Building Lifecycle and Demolition Patterns

Data Source & Methodology

This analysis combines data from the Boston Property Assessment Dataset (a snapshot of currently existing buildings) and the Boston Approved Building Permits (a historical record of work from 2009-2025). The methodology is designed to accurately link historical demolitions to the correct building records and interpret the results.

  1. Building-Centric Matching: To analyze entire buildings, not just individual condo units, a unified 'Building ID' is created. For condominiums, this ID is based on the shared CM_ID; for other properties, the PID is used. This ensures demolition permits for apartment buildings are correctly matched to the entire structure.
  2. Identifying a Single Demolition Event: A key challenge is that one building may have multiple RAZE (full demolition) permits in the dataset due to administrative updates or redevelopment cycles. The logic enforces a "one building, one final demolition" rule by:
    • Prioritizing permits that result in a positive lifespan (demolition year > build year).
    • Then, selecting only the most recent permit for that building.
    • Additionally, identical permits (same parcel and type) issued within a 24-hour window are consolidated to remove data entry noise.
  3. Interpreting Lifespan: Building lifespan is calculated by subtracting the construction year from the demolition year. The results are interpreted in two distinct ways:
    • A positive lifespan represents an observable, complete life cycle of a demolished building. These records are used to calculate statistics like average lifespan.
    • A non-positive lifespan (≤ 0) is not an error. It's a powerful signal of urban renewal, indicating that a historic demolition occurred on a parcel that has since been redeveloped with a newer building. These are categorized as "Demolished and Replaced" events.

Demolition Permit Types:
RAZE: Building Demolition(Instead of the 'demolished and replaced' part in Demolitions by Year plot, every plot's RAZE ONLY reflect positive life-span).
EXTDEM: Exterior Demolition (without razing the structure).
INTDEM: Interior Demolition (without razing the structure).

(Please note: As official definitions for these permit codes are unavailable, the explanations provided are based on standard industry terminology.)

Raze(Positive-lifespan)
0
Average Lifespan (Positive RAZE Only)
0 years
Avg Age of Current Buildings (Boston)
0 years
Exterior Demolitions
0
Interior Demolitions
0

RAZE Lifespan Summary

RAZE lifespan > 0
—
— Close — Open
RAZE lifespan = 0
—
— Close — Open
RAZE lifespan < 0
—
— Close — Open
RAZE total (by lifespan)
—
— Close — Open

This filter applies to statistics, the map, and all charts below (except the RAZE Lifespan Summary & Multi-RAZE plot).

Demolition Locations Map

Each point represents a demolished building. Color indicates demolition type. Hover over a point to see its lifespan.

Parcels with Multiple RAZE Permits

Shows only parcels (building_id) with multiple RAZE permits. The x-axis is the year; the y-axis is the parcel (building_id). For each parcel: the build year is shown as a green square (■), the latest RAZE is a red triangle (▲), and the remaining RAZE permits are circles (●).

Demolitions by Year

Age Distribution of Demolished Buildings in Boston

Age Distribution of Current Buildings in Boston

Shows the age distribution of all existing buildings in the Boston property assessment database

Demolition Type Breakdown

Age Distribution of Demolished Buildings by Year (Click Legend to Interact)

Shows the relative ages of buildings demolished each year, based on their lifespan at demolition

Construction Era of Demolished Buildings by Year (Click Legend to Interact)

Shows when demolished buildings were originally constructed, grouped by historical eras

Building Lifespan Distribution by Demolition Year

Each point represents a building's age at demolition. Points are jittered horizontally to show density.

Data Source: City of Boston Open Data | Analysis Date: 2025