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Everything you need to know about Boston triple-deckers

From key features to costs to financing options to the pros and cons of owning the famous housing type


Triple-deckers are a major feature of the Boston area’s housing stock. Also called three-deckers or 3Ds, they go back to the late-19th century, when the powers that be wanted a more sanitary and safer way to house the waves of immigrants—mostly from Ireland and southern Europe—crashing into the region.

It’s hard to say how many triple-deckers remain, but estimates peg it at around at least 15,000, with a plurality probably in Boston’s Dorchester neighborhood. They’re somewhat controversial today (more on that later) but they present an interesting ownership prospect for homebuyers as well as some challenges.

Here’s what to know about this famous Boston-area housing type.

What makes a property a triple-decker?

Part of the definition of the housing type is right there in the name: They are all three stories, generally with one unit per story. Some have been converted over the past century—construction of triple-deckers largely ceased in the 1930s—and therefore might have more than one unit per floor.

The other two defining characteristics are flat roofs and windows on all four sides. This last characteristic was considered a kind of triumph, a way to provide less affluent immigrant households with more fresh air and natural light. The four sides remain an appealing aspect of owning and/or living in a triple-decker.

Triple-deckers also tend to have one front door that leads to all levels, and they often have prominent front and back porches—all the better to let in more of the outdoors. One last thing: Triple-deckers were invariably made from wood frames, a cheaper material that allowed for quicker construction. Account for that when considering buying one.

How much do triple-deckers cost?

The answer to this question starts about 70 years into the triple-decker trend. By the 1950s, the children and grandchildren of the immigrants most apt to own or lease triple-deckers moved out for roomier digs beyond the core urban areas where the properties had sprung up.

A lot of triple-deckers fell into disrepair as a result, but that set them up to become investment opportunities as the region’s inner neighborhoods came roaring back at the end of the 20th century.

Investors and urban emigres snapped up the dilapidated properties, and many triple-deckers ended up as condos or as fixed-up apartments. Each iteration came along as regional housing prices and rents bounced—lucky for their owners.

Triple-decker prices then vary. Condos within them trade individually, so owning an entire triple-decker in that case means buying every condo. The median Boston condo price at the start of 2020 was $700,000, and the median regional condo price was $577,500. Proceed accordingly in that regard.

As far as buying a triple-decker that’s been converted into apartments, the total costs depend on the location and myriad other factors, including any further renovation costs or insurance. The initial price, though, can usually be gleaned from stats about three-family homes in general in the region—since three-family homes are usually triple-deckers.

The median three-family sales price region-wide was $929,900 in January 2020, according to the Greater Boston Association of Realtors and the Warren Group, a research firm. The average price per square foot was $310. Both measures were up from January 2019.

For comparison, the two-family median was $701,500 in January 2020, and the single-family median was $605,000.

What are the advantages and disadvantages to owning one?

The single biggest advantage to owning a triple-decker, particularly as an apartment building, is that the Boston region is one of the most expensive rental markets in the U.S. because of perennially high demand and traditionally low supply (among other factors). Median rents in cities and towns across the area, including in Boston proper, generally run to more than $2,000 a month. So you will definitely get a return on investment over time.

That “over time” is key though. One of the big disadvantages to owning a triple-decker is the upfront costs, including the purchase price and any renovation work. That can eat into any initial income from rent. And the best-case scenario for steady revenue usually hinges on the owner either self-managing the triple-decker and/or living in one of its apartments.

If that’s not the case, then factor in the costs of a management firm. Though, if that is the case, then that gets at another big advantage to owning a triple-decker, one that immigrants 125 years ago would have also readily recognized: It’s a place for the homebuyer to live while collecting income from the other units.

A frontal shot of two three-story apartment buildings. Shutterstock

Can you finance a triple-decker with a traditional mortgage?

Yes in most cases. Current regs consider properties of up to four units residential rather than commercial—so, unless your triple-decker is more than four units, you can apply to a bank, a credit union, or another lender for mortgage financing as you would for a condo or a single-family. The usual measures will apply, including credit scores and potential down payment.

There is a caveat for those investors who do not intend to occupy their triple-deckers. These investors are limited to conventional mortgage loans.

On the other hand, owners intending to occupy a unit in their triple-decker can choose between Federal Housing Administration loans, Veteran Affairs loans, or that conventional financing (depending on qualifications for each). What's more, down payments might be less for owners occupying a triple-decker than for investors.

This all sounds like an interesting opportunity. Why are triple-deckers controversial?

The Boston region suffers from a housing shortage. That’s one of the big reasons rents are so high. Triple-deckers occupy huge swathes of prime property throughout the region, and they’re each only three stories and a handful of housing units at most.

See where this is going? Some residents and officials feel that the land these triple-deckers occupy could be better used for taller and denser residential buildings, thereby increasing the housing supply and potentially bringing down rents and prices.

For now, though, triple-deckers are here to stay. The City of Boston even launched a multimillion-dollar preservation initiative for the properties in 2012. The region is almost unimaginable without them.

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