How "One-Plus-Five" is Shaping American Cities

Nobody would for one minute mistake a car or an airplane from 1955 for one from today. Everything, from technology to style is just too different.

By contrast, enter a new house or an apartment and clues that give away the newness are harder to find: They may be obvious in kitchen and bath, but even that is not certain, since fashionable retro stoves and claw-foot tubs could be deceiving even in those places where technology would be most likely. The new house would probably be more open and bigger, but from light switches to receptacles, from door hardware to double hung windows, things look essentially the same. On second glance, though, things in the new house feel flimsier, thinner and less substantial. Maybe there is a white plastic porch railing masquerading as solid wood or vinyl siding doing the same, maybe the doors are light, hollow and molded instead of being made from actual wood panels.  This general impression might deepen when one starts looking "under the hood": copper and cast iron pipes replaced by PVC, true dimension heavy wood joists and posts replaced by engineered trusses, strand board, and quick growth studs light as cigar boxes. Slate has yielded to asphalt shingles, wood floors have become laminate, and porcelain sinks replaced by cultured stone. Brick now comes as a thin cement imitation, cornices are made from Fypon, and flagstone water tables are only paper thin. 

One could discuss all that in the context of cultural criticism and bemoan what did change ("nothing is like it used to be") or, alternatively, decry that not enough has changed ("the construction industry is stuck in the Middle Ages"). Both cases could be made with ease.  Change in the construction industry, indeed, seems to be glacial.  On the other hand, the critique of the loss of a more substantial architecture could be based on more than nostalgia. It could be based in resilience (withstanding forces of nature) or sustainability (flimsy construction and rapid decay as waste). 

The Baltimore Jefferson Square project is a typical One-Plus-Five
(photo: ArchPlan Inc.)

The rather recent appearance of the "one-plus-five" formula has moved the debate from the suburbs to the city and from a discussion about components to one about whole buildings and even urban form. What is "one plus five"? It is the wood construction, "stick-built" urban mixed-use building, exactly five stories tall, erected on a concrete podium. The first level capped by the concrete deck is retail, parking, meeting rooms or amenities and the floors above it are apartments, condos, or dormitories erected under the 3A construction type classification of the building model code IBC. 

The International Building Code (IBC) allows wood-frame construction for five stories and more by meeting Type III-A construction requirements. Another level above grade may be added if the building includes a concrete podium, per Section 509. This allows the wood structure to be considered as a separate and distinct building for the purpose of determining area limitations, continuity of firewalls, limitation of number of stories and type of construction.

BUILDING HEIGHT: IBC 504 Increased height = 85 ft and 5 stories IBC 504.2 The portion of the building below the horizontal assembly is not limited in height or area because it is of Type I construction. The area above the podium is going to be 5 stories and a total of 62 feet above grade, but IBC Table 503 limits the number of stories to 4 and the total height to 65 feet. IBC 504.2 allows an increase of one story and 20 feet in height for most occupancies, R-2 included, when the building is equipped with an NFPA 13 sprinkler system throughout.  

With the stroke of a pen (via IBC 2009) an entire building group, the urban elevator building, moved from being a substantial structure made of concrete, steel or brick to one that is put  together with two-by-fours like a single family home. This change amounts to an often overlooked revolution in the construction industry and in urban development. 

The now allowed one-plus-five type is taking American cities by storm and shaping them along the way. This change is possibly even more impactful than the practice of defining “high-rise” by how high a fire ladder used to reach (75 feet), or “walk-up” by how far a person was willing to climb stairs (four stories). 

The One-Plus-Five is the prevailing building type in the up and
coming area of San Diego east of the library
(photo: ArchPlan Inc.)

Until a few years ago, it was fairly uncommon for an architect to go beyond four stories with wood-frame construction. Today, many designers choose five stories of wood over concrete podiums as a way to cost-effectively increase the density of projects. (Architectural Record  March 2014)

The new code permissions nicely coincided with the rebound of the construction industry after the Great Recession, with multi-family housing bouncing back first. Baltimore, often rather a follower than a leader, hadn't seen much of this new type until it finally recovered from the Great Recession and dusted off some dormant projects, such as Jefferson Square. Now, on the hill between the famous John's Hopkins Hospital and swanky-but-historic Fell’s Point, one can see an entire block of the one-plus-five architecture being extruded like toothpaste, straight, curved or around a corner, however you like until a whole city block is complete.

It was a couple of years ago in Seattle, that an architect friend pointed to the sameness of block after block of this type of construction in his rapidly gentrifying neighborhood. The sameness isn't like East Berlin's "Plattenbauten" (precast concrete buildings) around Alexanderplatz, nor has it the uniformity of some of Baltimore's rowhouse neighborhoods. These new one-plus-fives often actually offer a pleasing variety of architectural treatments, especially the West Coast varieties. They follow all the rules of new urbanism in that they form a street wall, accommodate a mix of uses and often provide an attractive sidewalk experience. The sameness, except for the fixed height and built-to line, is not obvious, because it consists in the rather complex but ultimately stifling uniformity in which architects and developers are trying to do the right thing to conceal the monotony of "one plus five." 

Seattle One-Plus-Five under construction (photo: ArchPlan Inc.)

They go to great lengths to vary materials, window patterns and use classic tectonic tools such as base, middle and top to break down the massing. But once one sees through this pattern, the visual splendor of this game seems stale, trite and becomes utterly predictable.  Dressing up the one-plus-five extrusion box doesn't make architectural excellence any more than bouillon cubes and water make a gourmet soup. The base created by thin veneer, the cement boards, the synthetic stucco over styrofoam, the smattering of brick (substitute brick for whatever the assumed vernacular of your region is), the corner turrets that stick up slightly above the roofline of the extrusion, all these design moves are arbitrary, capricious and without either innovation or true historic reference and amount to little more than draping a popular wall paper over all the wood sticks and cheap thin sheathing. The result is instant urbanism draped in the garb of the season, ready to be replaced by another fashion a few years down the road.  

One Plus Five in San Diego on Market Street (photo: ArchPlan Inc.)

The one-plus-five becomes a bit more convincing when broken up by a sloping street which forces a drop in the relentless roof and window lines.  But developers often flaunt this relief even on sloped sites to .save cost. They rather make the base extra tall on the lower end of the block for a type of retail that may find this additional height attractive. 
Fire safety reviewers have concluded that the added sprinkler requirements would make these buildings as safe as those constructed from non combustible materials. Maybe so. However, sound separation, privacy and a sense of stability are hard to come by in a structure made entirely of light lumber. The 15%-20% cost reduction may make affordable housing projects more attainable or even result in lower rents, but the quality of living the in wood apartments is likely not the same as the one in those where floors are concrete.

So far this critique isn't about urban design yet, the consideration of building height in the urban context or block edge construction as a typical city pattern. As noted, the one-plus-five, architecturally deficient as it may be, complies with the prevailing thoughts about how cities should be built, namely the rules of new urbanists: It forms a streetwall, its height typically corresponds well with the street width and its first floor is special and responds to street users via an active use such as retail. The retail, though, which comes with the type almost as a side effect, poses its own set of problems because there is usually much less demand for retail than there is for housing, especially since these floors are rarely designed for retail but follow the residential footprint above. With the proliferation of the building type it will be harder and harder to find retail tenants for all the first floor space and developers frequently opt for ample amenity spaces, instead, which do not quite provide the same pedestrian experience, though.

To build urban multi-family is quite in sync with the trend of populating city centers and giving downtowns a more diverse use than the office mono-cultures of the past.
Like good architecture, though, urban design excellence cannot be achieved by following a few simplistic rules alone. Good streets have a diversity of buildings on them, built at different times and by different architects. Real diversity is more serendipitous than the forced instant potpourri of the one-plus-five. It would include unexpected variations in setbacks, height or window types, variations on how stairs are done or where elevators are placed, in short, a more nuanced genesis than one developer's blueprint can offer.   

That this building type can easily slip into a variety of settings can be studied in the case of Washington, DC with its famous height restrictions and its penchant for a more homogeneous than invigorating architecture. DC created elaborate rules for heights in relation to the Capitol but also in respect to fire hazards, street width and geography. In DC's recent startling growth spurt and building boom, the one-plus-five type provided the perfect response for the new residents to get accommodations where space for new construction was available: the Navy Yard, Columbia Heights, the area around the arena that used to be Chinatown. The one-plus-five does not quite reach the 100'-130' limits that apply in this city with its almost European skyline. Thus, thankfully, one can find in DC also many new, taller and more substantial buildings with concrete floors and steel studs, even though stronger bones are no guarantee against pastiche architecture, as the redevelopment along Pennsylvania Avenue has long demonstrated.

Maybe, then, the attempt by architects to please in the cheap and predictable way of a beach novel, or the general timidity that seems to have befallen the profession here in the US, are not the defining problem of the one-plus-five model.  Perhaps instead, there is a much bigger set of problems.  Maybe it is not the architectural skin that is the real culprit, but the decay of the quality of the bones that is occurring in cities across the North America under the guidance of the IBC (Canada is just now in the process of approving taller wood buildings as well) . Where the bones are a sad jungle of skinny sticks, what can be expected of the skin?

For centuries the quality of their buildings and a certain permanence set cities apart and allowed

Nothing but sticks

decades and centuries of layers to create the textual richness we associate with them. City buildings could be reused in many ways because their structure were still good after 50 or a hundred years or more. Baltimore has a rich tradition in creative reuse of beautiful breweries, factories, mills and warehouses, each with substantial bones and each having been once each a trail blazer of sorts for innovation and skills. It is hard to imagine that fifty years onward folks would get excited about the one-plus-five buildings or contemplate an adaptive re-use. Too flimsy to last even that long, these buildings will probably have to be demolished once they become obsolete, unable to stand as the testimony of our times.

Klaus Philipsen, FAIA

edited by Ben Groff

In an early adaptation of the framed type 3A building over a concrete podium, the 2007 Aliceanna building in Fells Point, the author's firm, ArchPlan Inc. replaced wood studs with 6" metal studs, wooden exits stairs with steel and concrete stairs and added drywall layers to achieve the 50db sound separation. The front facade is brick and stone. The building had only the then allowed four levels over the podium but included mezzanines and roof deck penthouses.

Links:
The Five Story Wood Building over a Concrete Podium
Five story wood frame structure over podium slab
The Four Plus One Chicago Building Type

Related articles on this blog:
The Renaissance of the Apartment Building
Why 2,400 people die in house fires every year (Feb. 2017)
Brandnew and up in flames (April 25/2017