How parking affects missing middle housing
Missing Middle Housing types are key to affordability, but parking (and zoning that requires off-street parking) impacts the cost. This analysis by Dan Parolek of Opticos Design, author of Missing Middle Housing, shows that fourplexes—one missing middle type—may yield from 21 to 49 units per acre, depending on their number of bedrooms and the off-street parking provided.
In other words, parking can cut the net density in half. The buildings with no parking may achieve higher densities and lower costs. (In an urban neighborhood, on-street parking is typically available). Having an alley also allows for a smaller lot, even when parking is provided, because there is no access driveway needed. Parolek posted this analysis, from his book, on LinkedIn:
“This set of axonometric drawings demonstrates the impact on necessary lot size if you try to or need to integrate parking onto the site. Across the top is a fourplex with one-bedroom units and across the bottom is a fourplex with two-bedroom units. It shows both alley-loaded condition and front-loaded/non-alley conditions. This increase in lot size and construction of garages greatly impacts how attainably priced these units can be delivered for. Note: This only shows one parking space per unit. You can imagine the impact of trying to get two parking spaces per unit onto a site with the fourplex. It often makes a fourplex project infeasible to try to do this.”
Parolek adds that parking could be tucked under the buildings, “but then it would push the building up to three stories, greatly increase the cost of delivering this unit, and compromise the quality of the living condition in my opinion.”
He concludes: “I think you could build these in any market and have unlimited demand for rent and for sale if zoning would allow it.”
One of the images, on an alley, shows parking but no garage, at 32 to 37 units per acre. It also could be built with a carport. The fourplex can be converted to a fiveplex by dividing one of the ground-floor units into two units, which Opticos explains here. This building type has many options to fit particular markets and costs, if the zoning allows.