By and large, these are stories of the people who inhabit homes and neighborhoods, and how they’ve changed. But what about the homes themselves? What can they reveal about Detroit’s history?
Using data from Detroit’s Office of the Assessor and the 2014 Motor City Mapping parcel survey, Data-Driven Detroit examined the age of Detroit’s housing stock, the materials it was built with, and how they have stood the test of time.
The data from the Office of the Assessor is by no means perfect, but it does provide some insight in the range of housing within the city. Large numbers of parcels are grouped around decade markers, apparently because there isn’t a precise year available. This analysis has been conducted under the assumption that those assignments of age are at least relatively accurate.
Boom and Bust
The growth of Detroit throughout the 20th century has been characterized by three periods of explosive growth.
While a smattering of homes built before the 20th century are still standing, slightly more than 40% of Detroit homes were built in the two decades before the onset of the Great Depression. It was a slow ramp-up from 1910 to 1931, as Detroit’s industrial might continued to grow, but marked the first boom in housing with a string of high-growth years in the 1920s.
In the years after the great crash, construction came close to a complete halt, but then gradually began to climb back to pre-depression levels, marking the city’s second housing boom. By the time the U.S. entered World War II, more than 60% of the current housing stock had been constructed. Construction slowed significantly during wartime, and in 1945 was at its lowest level since Detroit began to recover from the depression in 1936.
The slowdown was shortly-lived, though, as troops returned after the war’s conclusion housing exploded once again. The sustained growth of this final boom also saw a deluge of smaller single family homes constructed with higher-quality materials. By 1956, more than 95% of homes currently in the city had been built.
If these walls could talk
Viewing Detroit’s residential parcels by the year each structure was built shows there are trends not just in the number of structure built, but in the materials they were built with.
The majority of Detroit homes – about 56% of the homes in the assessor’s data – have brick exteriors. And they are markedly more resilient than other homes. Brick homes were anywhere from 7 to 20 percentage points more likely to be labeled in “good” condition, the highest condition rating from the 2014 Motor City Mapping parcel survey, when compared against other exterior types, such as asphalt, wood siding, or asbestos shingles. About 95% of Depression-era homes are brick, for reasons D3 hasn’t explored.
The next most prevalent exterior material is asphalt siding, which was used in more than a third of homes built in the two decades before the Great Depression as a cheaper alternative to brick. Nearly 60,000 Detroit homes are clad in asphalt.
Wood siding was nearly as popular in that period, but was largely replaced by asbestos shingles after the economy recovered in the late 1930s, after about 35,000 homes were built with wood exteriors. Close to 20,000 homes in Detroit still have asbestos siding, as the material remained popular until home construction in the city essentially petered out in the mid-1970s.
Wood siding has seen a resurgence in popularity in the 21st century, along with more modern materials such as vinyl.
Despite these distinct trends in building materials, Data-Driven Detroit hasn’t been able to single out any one building material as a signal for housing quality. How well a house is maintained may remain the best determinant of the condition it will be in today, regardless of how old the home may be or what it’s built with.
What’s typical and what was popular
The majority of Detroit’s housing stock is a far cry from the newly-rehabbed darlings gracing real estate blogs. The typical Detroit house is a brick, 1 to 1.5 story, single family home with a 1.5-car detached garage built in 1937. About 70% of Detroit’s homes are less than two stories tall, and about 85% were built for single-family occupancy.
Nearly 10% of all structures are coded as a “two family flat,” the prevalent two-story homes with overhanging second-story porches and two front entrances. Another 5% are coded as an “income bungalow,” which were in vogue in the 1920s as a slightly larger bungalow where the upper floor, with a separate entrance in the rear, could be rented out for some extra cash to substantially reduce the purchase price of the home. Both of these were prominent styles of home prior to the Great Depression, when together they comprised about a fourth of all construction. Afterward they never exceeded more than a tenth. The post-war boom years were dominated by single family homes.
These data reveal that while Detroit is full of unique homes and architectural splendor, large segments of housing contained within its 139 square miles is based on similar plans, and was built within the span of 50 years.