Postwar housing stock that is all hitting the same wall
Nassau's residential base was largely built in a compressed postwar period, and Levittown is the textbook example: thousands of similar homes, many with radiant slab heat, later-added ductwork, upgraded panels, and mechanical systems installed by three different generations of contractors. Massapequa and Freeport add postwar ranches and capes with converted attics and finished basements. Garden City and Mineola bring older, larger homes with more complex systems and higher expectations. Hempstead spans a wide mix, including a substantial share of two-family and rental properties.
The practical consequence is that housing stock across a whole town tends to age into replacement at the same time. That is good for revenue and brutal for scheduling, because demand arrives in clusters rather than evenly.