This document discusses Lexington, Massachusetts' experience with "mansionization", where the size of new single-family homes has greatly increased over time. It notes that in 1987, the town began requiring larger setbacks for homes over 2,500 square feet as homes were getting much larger. Through the 1990s and 2000s, the planning board attempted to address the issue but proposals to regulate "jumbo houses" failed. While larger homes increased property values, they also diminished economic diversity and housing affordability while stirring conflict over neighborhood character changes. The focus is now turning to regulating building mass through residential floor area ratios.

1. Mansionization
Lexington's Experience

2. Mansionization
 In 1987, TM inserted a requirement for increased
setbacks for houses greater than 2,500 SF
– Setbacks set in 1953, when new houses ~ 1,200 – 1,800 SF
– By 1987, new homes were ~ 3,000 – 4,000 SF
– In 2008, new homes exceeded 7,000 SF
– 2010 average for Northeast 2,613 SF (Census Bureau)
 1992, Town staff starts tracking teardowns
 1994, PB develops, but pulls “Jumbo House” Bylaw
 1997, PB publishes New, Larger Houses in Existing
Neighborhoods
 2002, PB’s “House Impact Review” Bylaw defeated

3. Single-Family Development
0
10
20
30
40
50
60
70
80
1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012
Net New Teardowns

4. Conflict & Resentment
 Character (Scale & Aesthetics)
 Diminished Economic Diversity
 Loss of affordable housing
 Anti-development

5. Potential Positive Effects
 Increased property values
 Encourages and increases viability of
further development
 Increases consumer purchasing power
at local businesses
 Invisible to MGL 40B denominator

6. Unclear Effects
 Reduction of suburban sprawl
elsewhere in the region
 Increased/decreased incentive to
invest in existing housing stock
 Costs/changes to local services
 Population increased/decreased
 Increased/decreased diversity

7. Conclusion
 Fiscally beneficial
 Driven by high property values
 Related to our proximity to build out
– This magnifies character issues, because
it’s happening in developed areas
 Town Meeting has been ambivalent, but
 Stirs up enough interest to keep it on a
slow boil
– Focus now turning to Residential FARs