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  • Writer's pictureSteven Banninger

Heavy Timber Skyscrapers and Net Zero Zoning: Our Green Low-Cost Housing Future?


Our Future Bostonia: An in depth look into the Evolution of Boston into a Mid-21st Century City, what it means for our communities and competing public interests.

Every Monday & Tuesday; By Steve Banninger, Architecture and Urban Planning Writer for

Living in Boston for the past few years, I kept hearing the words Suffolk Downs over and over again whenever the cost of housing was brought up. I soon realized that this wasn't the first time I had heard of the racetrack; the first time I heard "Suffolk Downs" I was young and was picnicking with my family at another horse racing track, in Monmouth, New Jersey.

Fast forward to today, and my family's go-to alternate racetrack for horse racing sits mostly empty except for a solitary 475-unit building apartment building; 475 of what was supposed to be 10,000 units. These were supposed to be a game changer in our housing crisis. However, Suffolk Downs is no longer the silver bullet solution it once was with rising costs being affected by two things, interest rates and the price of construction materials.

Why is the cost of building new housing rising?

“Imagine you had a building that was before returning 6 percent” on an investment, said Adam Guren to the Boston Globe, an economist at Boston University. “With a higher construction cost you’re returning maybe 4 percent. That building used to make twice as much income as was necessary to build. Now it’s not enough.”

“The equity is literally like an on-off switch,” developer at HYM Invesment Group Tom O’Brien said to the Boston Globe. “Either you get to the six and a half percent return on cost, or you don’t have a project.”

According to the Globe, interest rates on construction loans are 5% higher than they were in 2022. This is due to an attempt by the fed to fight off inflation from recent attempts to sustain the economy, and our communities, during the COVID pandemic. "You can walk down to your local bank and get a (certificate of deposit) at 5 percent,” said Ted Tye to the Boston Globe's Spot Light Team, he is a partner at Newton-based builder National Development. “If I can do that, why would I take a risk on a $100 million housing development to get a lower return?”

The cost of lumber and steel have come down from their pandemic '20-'22 highs but still have not returned to their 2016 levels with steel returning much slower than wood. Construction material in general remains high however, according to the US Bureau of Labor Statistics.

In a 2022 Mayor's Office of Housing Report, from 2017-2021 only 20,000 units of housing were built. MassHousing says that 20,000 mixed-income housing units are on pause, which would make up for the previous years lack of production. The delayed units had been developed under the 40B law that allows developers to ignore zoning laws if the town does not have enough affordable housing.

Heavy Timber Skyscrapers

"Large timbers, because of their greater capacity to absorb heat, are much slower to catch fire and burn than smaller pieces of wood. [Wood Light Frame Construction, typically seen in Single Family Homes] When exposed to fire, a heavy timber beam, though deeply charred by gradual burning, will continue to support its load long after an unprotected steel beam exposed to the same conditions has collapsed. If the fire is not prolonged, a fire-damaged heavy timber beam or column can be sandblasted afterward to remove the surface char and continue in service. For these reasons, building codes in many circumstances recognize heavy timber framing as roughly equivalent to steel, concreate, or masonry with a one-hour fire-resistance rating." Edward Allen & Jospeh Iano in Fundamentals of Construction Sixth Edition

That quote was from a construction materials and methods/structure textbook published in 2014 that I used in my first structures class. Allen and Iano continue, that in the International Building Code, the basis for Massachusetts's Building Code, timber construction is classified as Type-IV Heavy Timber; the 2021 IBC creates Type IV-A, IV-B, and IV-C which allows for Constuction up to 18, 12, and 9 stories each. Allen and Iano also make mention of the sustainability of specifically glue-laminated and cross-laminated members (beams and columns) by utilizing the wood fibers more efficiently and by making use of more of the log. Some have called these towers, "Plyscrapers"; the tallest timber tower in the in the world is the Ascent Tower in Milwaukee, Wisconsin.

PC: City of Boston Planning Department- Rendering of Longwood Place

The Suffolk Downs development actually had two timber frame buildings in the first round of the Mass Timber Accelerator program, both eight stories that would have included market rate, affordable, and senior housing; the fate of these projects now hangs in the air of a complicated financing deal HYM is pursuing. The Bunker Hill Housing Redevelopment, 18-32 Spice Street (24 Spice), and Longwood Place all won funding in the second round of the Mass Timber Accelerator which released it's final report in April on Earth Day 2024:

  • Bunker Hill Housing Redevelopment by Leggat McCall Properties & Stantec- Two affordable and mixed- income multi-family housing buildings at 6 and 9 stories

  • 18-32 Spice Street by RISE & CBT Architects- 365 residential units at 24 floors with 20% affordable units

  • Longwood Place by Skanska & Sasaki-mixed use development with three high-rise commercial buildings and two high-rise residential buildings

The Tenth edition of the 780 CMR Massachusetts State Building Code is expected to be published by the Secretary of State of Massachusetts soon and take effect on January 1st, 2025. Twenty-two states and two cities adopted the 2021 IBC in whole or part, when Steel prices spiked followed by two more states, and more cities this year. This is expected to compliment the Net Zero Carbon Zoning approved by the BPDA Board of Directors last month.

While the report touted timber's benefits including:

  • Efficient Floor-to-Floor-Height- A seven-story building can be built without triggering the building code 70' height limit that triggers high rise standards.

  • Reduced Building Weight- Reducing the cost of the foundation

  • Reduced Embodied Carbon- Instead of 50% of the carbon emitted from a building, mass timber emits 35% - 80% less than the same structure built with steel

  • Beauty and Biophilic Benefits of Wood- There is a marketable opportunity to sell the aesthetic benefits of exposed wood structure and panels to potential tenants

  • Accelerated Construction Time- CLT decking can be rapidly assembled allowing other contract work to take place sooner in the construction process

There were some drawbacks:

  • Lab/Office Use Vibration Standards- Timber structures still need to prove there is no risk to structural vibrations causing damage to sensitive office or lab equipment.

  • Supply Chain- New manufacturing facilities will need to be created to meet rising demand

In Conclusion

Fortunately, a recently proposed Momentum Fund of 50-250 million to get these 40B approved mixed-income stalled housing units, tracked by MassHousing, will be finalized in the coming weeks.

A new construction type isn't going to solve our housing cost issues in the commonwealth; but it will give developers new options when considering the costs for their projects and will set them up to increase the housing added by these projects. Accessory dwelling units, mass produced housing, the MBTA Community act, and possibly even eliminating single-family zoning in the city are all options we'll be taking a look at. It's important to understand the intertwined relationship between housing and transit, next week we will be taking a closer look at the relationship between housing and transit in the context of competitiveness in the post-covid age, Towards Our Future Bostonia.


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