The Diabolical Diagonal

Capitol Hill streets and building parcels are almost uniformly delineated by an orthogonal grid; however, when confronted with the second part of our neighborhood’s name the ubiquitous grid revealed its limitation as an all-inclusive planning tool and left city planners little choice but to utilize diagonal streets to ascend and descend our heights. Diagonal streets present a foil to the well-ordered grid, yet most buildings conform to the grid even when the site is an unconventional shape. There are reasons to stay square when designing a building, but design opportunities are sacrificed when the only nod given to an atypical, non-orthogonal site is to design an orthogonal building and treat its diagonally bounded site simply as a remainder to be ‘planted-up’.

The Hill’s longest and steepest diagonal street, Belmont Avenue, exhibits a variety of design solutions to the grid’s disruptive diagonal. The first approach, illustrated in two variants below, plays to both diagonal and grid in a manner that preserves the conflicting geometries. The third solution is a rarely seen hybrid approach where the geometries of grid and diagonal are blended and create unexpectedly complex forms. which gave us a pair of delightful mid-century apartments.

The Stagger (all taxonomic terms are the author’s)

One common design approach for an architect having to deal with a diagonal is to break the building into smaller components and stagger them along the diagonal street so the outer edges of the stagger create points implying a diagonal. This is a classic and very safe approach; no one part is left aching for the limelight. Harmony ensues. There are no awkward overlaps or acutely angled spaces, plus the Stagger translates nicely into the landscape, giving each component a distinct presence on the site.

The Juxtaposition

At first glance, the Juxtaposition may be considered as a slight variation to the Stagger. They each break the building into components to deal with diagonal irregularities, but unlike the relative harmony of the Stagger, the Juxtaposition sets up an opposition between the diagonal and the grid components of the building leading to a ‘both/and’ design. The choice of which particular alignment each component takes is revealing. In the building pictured below, the garages parallel Belmont Avenue and the apartment building is aligned with the Capitol Hill grid. The garages (which only store automobiles) kowtow to the rogue diagonal while the dwellings play it safe and stick to the grid. The garages acknowledge the presence of the diagonal and its roof houses (a remainder) garden terrace.

The building pictured below (photographed from Summit Avenue) is at the intersection of Belmont and Summit. The upper three floors, the dwelling portion of the building, parallel Belmont Avenue. The ground floor, which is visible only from Summit and grid-aligned, stores the automobiles and refuse containers. This is a reversal of the previous example and is the only building along Belmont Avenue where the entire, visible massing parallels that street. Note how the architect resolved the acute angle of Belmont and Summit with a cool, glass-enclosed stair.

The Shave

The third example of diagonal mitigation is a pair of mid-century apartments, 709 Boylston East (the taller of the pair) and the Belmont Roy. Both buildings not only take advantage of their site's unique geometries but play off one another’s designs so well that it seems certain the same team was involved. The apartments, pictured below, collage the Stagger and the Juxtaposition by utilizing a new design typology, the Shave. The Shave embraces the diagonal and orthogonal, molding them into distinctive geometries that are better connected to the uniqueness of their site than either the Stagger or Juxtaposition.

On 709 Belmont, the Shave begins at the intersection of Belmont Avenue and Belmont Place. The Belmont Place elevation, which is on the grid, has a normative, if not a bit exuberant brick wall. The shaved portion, partially aligned with Belmont Avenue, has the lighter, steel balconies, rough-sawn wood siding, and full-pane windows. The adjacent Belmont Roy Apartments further develop the Shave; the balconies are more transparent than on 708 and instead of turning the corner the balconies' plasticity and lightness are accentuated by the pulling back of the apartments, creating an acute and open corner. Unlike on 709, the balconies on the Belmont Roy rest on slender columns instead of a concrete deck, emphasizing the erosion of predicated by the Shave. On the Belmont Roy, which only fronts Belmont Avenue, the Stagger forms a landscaped courtyard where expansive balconies and large windows are oriented to take in the views of Puget Sound and the Olympics. At its northern edge of the courtyard there is a mural, unnoticed prior to this writing this post.

The 709 Belmont and the Belmont Roy have their shortcomings, including an open garage on Belmont and a blank wall along Roy. The Boylston Avenue elevations of both buildings are unremarkable. Still, the designers delivered one of the more dynamic and site-responsive apartment buildings on the Hill. If such thoughtful detailing and site-responsive design were more common on Capitol Hill, the pair would not be the standouts they are.