Aged Buildings

Definition

Aged buildings are the third of Jane Jacobs's four conditions for city diversity: "The district must mingle buildings that vary in age and condition, including a good proportion of old ones so that they vary in the economic yield they must produce. This mingling must be fairly close-grained" (Jacobs 1961, p. 151). The mechanism is overhead: "If a city area has only new buildings, the enterprises that can exist there are automatically limited to those that can support the high costs of new construction… chain stores, chain restaurants and banks go into new construction. But neighborhood bars, foreign restaurants and pawn shops go into older buildings" (p. 187). The book's most quoted line follows: "Old ideas can sometimes use new buildings. New ideas must use old buildings" (p. 188).

The concept is an economics of time: "Time makes the high building costs of one generation the bargains of a following generation. Time pays off original capital costs… Time makes certain structures obsolete for some enterprises, and they become available to others" (p. 189). A successful district is "a kind of ever-normal granary so far as construction is concerned" (p. 189). Its negative proof is the district "built up all at once": "Neighborhoods built up all at once change little physically over the years as a rule… It is dead. Actually it was dead from birth, but nobody noticed this much until the corpse began to smell" (p. 198). And its positive proof is the unselfconscious adaptations of the old fabric — "the town-house parlor that becomes a craftsman's showroom, the stable that becomes a house, the basement that becomes an immigrants' club, the garage or brewery that becomes a theater… the butcher shop that becomes a restaurant" (p. 193) — plus the incubation economy of Brooklyn: machinists starting "in the back of a garage… a rented loft… a building… [then] Queens, or Nassau or New Jersey. But in the meantime, twenty or fifty or a hundred more like them will have started up" (p. 196).

Key Thinkers

• Jane Jacobs — the concept's author: mingled age and "inherently varied overhead" as the economic requisite of diversity (1961).
• Grady Clay (not yet paged — see log) — the Louisville real-estate editor whose sample-shoe-market and Arts-in-Louisville case studies document incubation in low-yield space (pp. 161–162, 194–195).

Related Concepts

• mixed-primary-uses — condition 1: aged buildings shelter the primary diversity that new construction cannot incubate (p. 195).
• unslumming — the residential face of the same economics: "in unslumming slums, old buildings 'filter up'" (p. 193).
• adaptive-reuse — the wiki's design-practice register of the same fact: the Louisville building that "started life as a fashionable athletic club… [through] a blacksmith's, a factory, a warehouse, and it is now a flourishing center of the arts" (p. 195).
• self-destruction-of-diversity — the aged buildings' disappearance is what success does: "the admired and magnetic knoll is destroyed by its own new occupants" (p. 246).
• cataclysmic-money — the finance system that cannot supply gradual increments of new construction to age-mingled fabric.

Source Support

Sources in the wiki that discuss this concept:

• The Death and Life of Great American Cities (Jacobs 1961) — condition 3 stated (p. 151; Ch. 10, pp. 187–198); the new-construction overhead argument (p. 187); "New ideas must use old buildings" (p. 188); the time economics (pp. 189–190); the corner-grocery gimmick (pp. 190–191); Stuyvesant Town's 22%-empty fronts against 7% on the age-mingled side of its bordering streets (p. 191); the commercial-monopoly planning of Society Hill and Hyde Park-Kenwood (pp. 192–193); the Louisville building-history catalogue (pp. 194–195); the Brooklyn incubator paradox (pp. 196–197); the one-age district "dead from birth" (p. 198); "the economic value of old buildings is irreplaceable at will. It is created by time" (p. 198).

Source Support linking rule: All entries in this section must be wikilinks to source note pages in wiki/source-notes/ using the source-notes/ path prefix. Never link to raw files — raw files are not wiki pages.

This page requires fuller treatment — created at the Jacobs ingest; awaits the heritage-economics literature and Jane Jacobs's later formulation in The Economy of Cities (1969).

Open Questions

• Jacobs's yield-mixture is a market argument (cheap space for low-yield uses), yet the wiki's gentrification sources describe the same cheap space as displacement's raw material. Is the "unslumming" building-stock and the "gentrifying" building-stock the same asset at different moments — and what distinguishes the two trajectories?
• The concept implies a planning duty to withhold (no blanket clearance, no one-age superblocks) rather than to build. Can a regulatory regime be built around a negative capability — and does "zoning for diversity" (p. 252) supply it?