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Extended Eave w/ Sprinkler Protection at Ankeny Row

Case Study by Chris van Daalen, Mary Stewart, Dylan Lamar
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Extended Eave w/ Sprinkler Protection at Ankeny Row
photo credit Green Hammer
Energy
Fire Safety
Materials
Passive House
Extended Eave for Passive Solar
City of Portland, OR
673338
Jody Orrison, Bureau of Development Services
Homeowners
Multifamily
Dylan Lamar, Green Hammer
Stephen Aiguier, Green Hammer
Designed to Passive House standard FSC-COC certification Earth Advantage Platinum
3/2015

Abstract

Ankeny Row is an environmentally-friendly, socially engaging cohousing community in Portland, Oregon with five townhomes, a loft apartment and a community hall surrounding a central courtyard. A Passive House development with a net-zero energy goal, the buildings use an airtight super-insulated building envelope, innovative heat recovery ventilation and passive solar strategies to sharply reduce energy demand.  Extended 48” deep eaves that shade the large south facing windows on the topmost floor, and a combustible material wood deck were approved after two successful code appeals, by including fire sprinkler protection.

Permitting Process Summary

An unenclosed eave with 48-inch projection at a common property line would normally be prohibited by fire safety code provisions, but was approved through a code appeal by placing sidewall sprinklers below the eaves, providing coverage of the eave for more than 3ft in each direction.  The combustible deck material was also approved through a code appeal based on placement of sprinklers.  The sprinkler system is certified NFPA 13D compliant.

Project Details

To meet the project’s sustainability objectives - which include net-zero energy performance - the community’s three buildings were sited so the courtyard could get the most sun penetration in order to maximize solar heat gains in winter and to prevent overheating in summer.  Proper exterior shading of windows is important to achieve this goal: If the eave were limited to a 24 inch projection within 3 feet of the assumed common property line as required by fire safety code, the windows below would not be properly shaded and overheating would frequently result.

Code RequirementCompliance Path
2011 Oregon Residential Specialty Code section R302.2.4.4 requires unenclosed eave of a townhouse within 3 ft of assumed common property line be limited to a 24 inch projection. One hour fire resistive protection is required. 48” unenclosed eave approved through a city code appeal, by showing design includes NFPA 13D sprinkler system with 3-foot coverage
2011 ORSC R302.2.2.2.3 Requires non-combustible or heavy timber deck within 3ft of assumed common property line when not adjacent to A second code appeal to approve combustible decks allowed because of sprinkler coverage

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Compliance Details

So the design includes an unenclosed eave with a 48 inch projection which is continuous across the assumed common property line between townhouses. The proposed design places sidewall sprinklers below the eaves at the assumed common property lines, providing coverage of the eave for more than 3 feet in each direction.

A NFPA 13D sprinkler is provided throughout the structure as required because portions of the building’s exterior are more than 150 feet from the street. However the eaves of concern are located within 150 feet of the street.

The building has a highly energy-efficient envelope with a peak heating load of each dwelling being about 1,500 Watts, about the size of a hair dryer. As a result the interior environment is very sensitive to unwanted solar gain which can cause overheating even in winter months. Operable exterior louvered shade systems are available but cost-prohibitive, so exterior shading is provided to effectively mitigate this solar heat.

In addition to limiting overhang projection for fire safety, the Oregon residential code requires buildings with a deck within 3 feet of a common property line to be constructed with non-combustible material.  Since the sprinkler heads installed to protect the extended eave will also provide coverage of the full area of the deck adjacent to the common property line, the need a non-combustible deck is diminished.  They used Ipe decking and sleepers over a low-slope membrane roof to maintain the residential character of the building and avoid the need for a commercial concrete paving system.

Ipe meets NFPA Class A and UBC Class 1 when tested under ASTM Test Method E84. Flame spread, smoke developed values, and fuel contribution ratings under this test indicate that ipe is not readily flammable and does not readily carry or communicate fire, thus offering a moderate degree of fire protection.

The use of Ipe hardwood is cost effective, meets sustainability objectives, is attractive, and is very durable. Although it does not have test documentation to demonstrate that it is non-flammable, tests have been done to show that it inherently has very low flammability characteristics.

Resources:

"How a Bunch of Retirees Created Portland’s Greenest Communal Housing Outpost" article in Portland Monthly,  By Kelly Clarke, 10/5/2015

For more information, visit the website of Passive House Northwest, trade association for ultra-efficient Buildings.

PortlandOnline - Code Appeal #9956 See additional suporting docs on City appeal page

Motivations and Design Process

Green Hammer worked with the homeowners for several months refining the design of the homes to meet the homeowners’ goal of net zero energy, low-environmental impact, durable homes built with sustainable materials.  Green Hammer supports all of these goals, and it carefully designed the homes to be net zero energy annually (producing as much electricity onsite with rooftop solar PV as the homeowners consume in their homes each year).  In order to reach this goal, energy-efficiency guided every step of design and construction.  Thus, all of the seven units approach or meet the Passive House Standard, the world’s most rigorous building operating energy efficiency standard that strictly limits air leakage, energy use for space heating and cooling, and whole-building annual operating energy.

According to Green Hammer's website:

Ankeny Row... is a shining example of sustainable urbanism. The project's location in an existing urban neighborhood on a designated bicycle route and in close proximity to public transportation allows the owners to live a car-free lifestyle if they choose. The owners wanted the community to feel welcome and connected to the co-housing project.

The building forms and site organization — townhouses arrayed around a central courtyard — are reflective of many examples of historic courtyard housing in the four quadrants of Portland.

The co-housing model furthers economic efficiency and expanded, shared amenities while improving social cohesion and connection. A common room and kitchen allow group and community activities and hosted dinners. A courtyard garden supports urban agriculture and provides an opportunity for residents to connect with the ecosystem in an urban setting. Convenient bike parking for the owners and their guests encourage cycling over driving to the site.

Project Contacts
Designer: Dylan Lamar Green Hammer (503) 804-1746 Approving Offcial: Jody Orrison Bureau of Development Services (503) 823-7526
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