419 OCCIDENTAL AVENUE, Seattle
ARCHITECT: SHED Architecture & Design
GENERAL CONTRACTOR: CHINN Construction
GLAZIER: Goldfinch Brothers
Located in the Pioneer Square district, the building needed to be redeveloped to fit the historic neighborhood’s shifting commercial landscape. Although the building’s early 20th-century architecture visually matched the surrounding designs, it would fail some necessary fire- and life-safety code requirements. One of these was a fire-rated stairwell that met egress requirements.
SHED Architecture & Design decided to bring the stairwell to the building’s exterior. This not only alludes to industrial fire escapes of the past but also sets the building apart visually from its neighbors. The design team chose to flood it with natural light by specifying two transparent glass curtainwall systems on the east and west ends, balancing design aesthetics with critical fire and life safety.
First, the south end of the stairwell had to incorporate fire-rated doors and windows to meet emergency-egress code requirements. Likewise, because the north end of the stairwell was load- bearing and less than 10 feet from a neighboring building, it needed a 120-minute fire rating. These requirements necessitated finding rated and non-rated assemblies that could create a cohesive design. Because the design also included windows with the cross-laminated timber (CLT) north wall, SHED Architecture & Design requested a code modification to specify rated windows within it while still meeting Seattle’s code requirements. To help solve these challenges, the design team turned to Technical Glass Products (TGP).
Because TGP’s fire-rated frames offer narrow sightlines with a fire rating, the manufacturer was able to provide a close visual match to the non-rated frames in the stairwell. This helped maximize the amount of light the stairwell could provide and contributed to a cohesive visual aesthetic.
“These products are no joke,” says Greg Shiffler, a senior architect and partner at SHED Architecture & Design. “The glazing is heavy and requires special crews, tools and knowledge.” The rolled fire-rated steel frames can accommodate unrestricted glazing area, ensuring the glass takes center stage. As such, they helped this aspect of the building renovation proceed as planned.
To increase access control, the stairwell’s ground-level entrance is located within the building. This design allowed the architectural team to include a fire-rated corner window system on the mezzanine level of the stairwell.
The window features floor-to-ceiling transparent glass held within black fire-rated frames to visually complement the building’s storefront and stairwell’s door and window systems. The mezzanine’s reclaimed wood paneling borders the framing system to further tie the new materials to the building’s history. The assembly provides a 120-minute fire-rating and adds to the natural light within 419 Occidental Ave.
In addition, TGP was able to offer guidance on requesting a code modification request with the city of Seattle. The stairwell’s north wall incorporated 60-minute fire-rated windows within a 120-minute fire-rated, load-bearing wall made of CLT. However, Seattle’s building codes did not cover installing fire-rated windows within a CLT wall, which meant the assembly would have been outside code requirements.
But there was a way to incorporate windows into the wall while meeting the intent of local building requirements. Because the CLT requires a one-hour “char depth” (as described in the 2015 National Design Specifications), it could provide leeway depending on the placement of the window in question. When set well beyond the char-depth limit, the 60-minute-rated windows satisfied the intent and requirements of the Seattle fire-safety codes.
FIREFRAMES SG CURTAINWALL SERIES, FIREFRAMES CURTAINWALL SERIES WALLS, FIREFRAMES DESIGNER SERIES DOORS AND PILKINGTON PYROSTOP FIRE-RATED GLASS: Technical Glass Products
PHOTOS: Technical Glass Products