A growing body of scientific literature demonstrates significant benefits to young children from nature-based education. Some of these evidence-backed benefits are seemingly self-evident, such as increased physical activity correlating with lower levels of childhood obesity and enhanced motor-skills development. Constantly changing weather is a direct stimulus that develops resilience and self-regulation. Regular exposure to nature is widely recognized as reducing stress levels in people of all ages.
Introducing CAST’s Infill Housing Toolkit: We put together recent, current, and future projects to showcase strategies and case studies for abundant housing infill development.
Site Typologies
Constrained Lots
Typical Infill Lots
Large, Assembled Lots
Design Features
Single Stair
Stacked Flats
Low-Energy Design
Low-Carbon Building
Diverse Unit Mix
Open Space
The Kirkland Cedar Cottage shines. It has an extremely efficient footprint that provides well daylit living space, necessary storage, flexibility, and a covered outdoor living area.
Bathed in natural light, a generous central area includes the kitchen, dining, and living spaces. The cottage is accessible with one-level living, flush entry thresholds and flooring transitions, a galley kitchen, and a generous entry that connects the spaces.
Carefully placed large windows and glass entry doors flood the area with light that bounces off the white walls to make it feel larger than its square footage. The open glass doors and deep eaves create a vibrant indoor/outdoor living experience.
Square feet: 467
Green Design: Energy-efficient heating, cooling, and water heating systems, passive solar heat gain in window/shading, all LED lighting, low VOC recycled and renewable materials, and no fossil fuel use appliances.
Interior Designer: Jayne Douglas Design
Builder: NW Finishing
Photos: Kara Mercer
This cottage was recently featured in Kirkland Lifestyle.
RiversMeet, a mixed-use project in the town of Winthrop in Washington’s Methow Valley, is positioned to become the upvalley entrance to “old downtown.” The site is a challenging set of narrow parcels overlooking the confluence of the Methow and Chewuch Rivers.
RiversMeet is envisioned as a template for how buildings can work within Winthrop's westernization code while striving for high levels of sustainability and providing more inclusive housing options.
The program will provide two 2-bedroom residential units overlooking the river, with approximately 1,870 SF of pedestrian-level retail space. The second floor incorporates 1,870 SF of office space. The second floor incorporates 1,870 SF of office space, continuing the client’s tradition of renting below market rate to community non-profit businesses.
GREEN DESIGN
1. Concrete mix uses fly ash, reducing use of higher-carbon cement
2. Low-Carbon Foamed Glass Aggregate replaces typical underslab foam board insulation
3. Gutex wood fiber exterior board insulation
4. Low-Carbon Wildfire Resistance Strategy:
- Wood siding treated with a non-toxic solution that provides fire resistance without the high carbon penalty of fiber cement
- Exterior sprinkler system
- Fiber cement siding reduced to areas where it's most effective
5. FSC-certified wood framing package
6. High-efficiency all-electric heat pump space heating
7. High-efficiency heat pump water heating
8. Solar array
TEAM
Client: Peter Goldman and Martha Kongsgaard
Architect: CAST architecture
Builder: North Star Construction Company www.Northstarbuilds.Com
Civil & Structural: DCG, now Facet www.dcgengr.com
Electrical: TFWB tf-wb.com
Environmental: Grette www.gretteassociates.com
Geotech: Geoengineers www.geoengineers.com/
Mechanical: Ecotope www.ecotope.com
Survey: Tackman www.tackmansurveying.com
ECHO, a 10-unit apartment building in the Eastlake neighborhood of Seattle, is now a Design Certified PHIUS (Passive House Institute US) Core 2021 project.
This apartment building will replaces a single-family structure in this residential urban village, adding missing-middle housing. It utilizes the stacked flats concept which pushes the bounds of the single-family envelope but maintains an urbanism-friendly street frontage.
The two homes on the ground floor are both fully accessible. And, the top two units have high ceilings with lofted sleeping areas.
High-performance design elements include: thermal control, airtightness and moisture control, balanced ventilation, and high-performance glazing.
TEAM
Developer: West Crescent Advisors, LLC, Nancy Melton
Architect: CAST
Passive House Institute US: @passivehouseinstituteus
Builder: Carrig Construction @carrig_construction
Project Consultant: Woodworth Construction Management LLC, Lydia Anne, @woodworth_built
Civil Engineer: Davido Consulting Group, Inc. @dcgengr
Structural Engineer: Harriott Valentine Engineers @harriottvalentine
Mechanical Engineer: Ecotope @ecotope_inc
Envelope Consultant: B.E.E Consulting, LLC
Electrical Engineer: TFWB Engineers, Inc
Windows: Alpen Windows – Passive House Certified
Landscape Architect: @karenkiestlandscapearchitects
Arborist: Moss Studio
Geotechnical Engineer: PanGEO, Inc.
Surveyor: Terrane @terranesurveying
Third party verifier: Balderston Associates
Chris Walter, @ChrisWPhoto, talked with Matt Hutchins about the significance of Accessory Dwelling Units (ADUs).
At CAST architecture, we have been focused on ADUs for more than a decade. They're fun to design, perfectly fit a niche for new housing in established neighborhoods, and provide many benefits for owners and residents.
https://www.youtube.com/watch?v=PJaLht9v5Yw
CAST’s Cedar Cottage is a City of Seattle Pre-approved DADU. Our vision is to adapt the high-design cottage, simplify it, and make it accessible.
See more at www.castcottages.com
“Part of the reason we love backyard cottages is just the opportunity. If you have a home with a possibility for a second house – it could be whatever you want it to be – a studio, a place for grandma, a rental, and having that flexibility is huge. We have people who have it as an Airbnb, or a long-term rental, as a place for their kids and then their retirement home. This flexibility is fantastic. It opens up so many opportunities in this great city.” -- Matt Hutchins, AIA, Certified Passive House Designer
Backyard cottages = Flexibility and Opportunity
ON THE BOARDS - METHOW VALLEY’S RIVERSMeet WINTHROP proposed MIXED-USE BUILDING
RiversMeet, a proposed mixed-use project in the town of Winthrop in Washington’s Methow Valley, is positioned to become the upvalley entrance to “old downtown.” The site is a challenging set of narrow parcels overlooking the confluence of the Methow and Chewuch Rivers.
CAST’s client, Peter Goldman, as part of his development proposal, intends to request the town make zoning changes to allow for long-term rentals in the commercial district. RiversMeet is envisioned as a template for how buildings can work within Winthrop's westernization code while striving for high levels of sustainability and providing more inclusive housing options.
The program will provide two 2-bedroom residential units overlooking the river, with approximately 1,870 SF of pedestrian-level retail space. The second floor incorporates 1,870 SF of office space. The second floor incorporates 1,870 SF of office space, continuing the client’s tradition of renting below market rate to community non-profit businesses.
Team
Client: Peter Goldman and Martha Kongsgaard
Architect: CAST architecture
Builder: North Star Construction Company www.Northstarbuilds.Com
Civil & Structural: DCG www.dcgengr.com
Electrical: TFWB tf-wb.com
Environmental: Grette www.gretteassociates.com
Geotech: Geoengineers www.geoengineers.com/
Mechanical: Ecotope www.ecotope.com
Survey: Tackman www.tackmansurveying.com
Give Middle Housing a shot!
Matt Hutchins’ comprehensive discussion, at Medium, of the Washington state Model Code for Middle Housing and how we can have it produce more housing in line with HB1110.
In HB 1110, the State Legislature read the will of the people and demanded that we tackle the housing crisis more proactively by allowing Middle Housing in most cities and towns. Washington State Department of Commerce has created a basic zoning template that supersedes local code if town planners balk at updating their own code to comply. The draft version of that Middle Housing Model Code is out for comment (comment here by December 6th!). I have analyzed the real world implications of how it would regulate new housing and how we can tweak it to better support the creation of townhouses, flats, and infill development.
Here are my recommendations:
1. Allow Middle Housing to be larger than single family houses: more lot coverage, smaller setbacks, and make them taller.
Diagram of current allowable single-family building sizes in 6 cities to illustrate that the Model Code’s Floor Area Ratio system is actually more restrictive.
It seems like an obvious point that the bulk of a building or buildings for up to 2, 4 or 6 households might be larger than one with just a single household, but a close look at some of the cities governed by this new legislation reveals that the draft code is MORE restrictive than current codes. It would effectively be a downzone in structure size in order to house more people. That isn’t a good trade, and for all the proof that Middle Housing has wide ranging benefits, we should have a code that supports it.
Middle housing is not just a bridge between the densities of single-family neighborhoods and denser areas, it is also a incremental increase in size between those building types.
2. Measure lot coverage, not FAR
There is a policy conversation about two methods for measuring building size: 1) lot coverage X height vs. 2) lot size X Floor Area Ratio. The draft code uses FAR for Tier 1 and 2 cities (the larger cities and the municipalities around them), and Lot Coverage for Tier 3 cities (smaller cities).
In the six Tier 1/Tier 2 cities I picked to analyze, five use lot coverage not FAR. The model code should follow suite. It is easy to implement, understand and compare apples to apples to existing codes.
Diagram of small cities buildable footprint illustrates how extra flexibility in lot coverage will translate to new housing for those communities.
Meanwhile Tier 3 cities, the code uses lot coverage to provide flexibility for how to develop successful infill housing, because lot coverage isn’t the critical threshold, the market is. I think this part of the Model Code will be actually be good for many smaller jurisdictions that are struggling with housing cost and access.
3. Set thresholds by looking at what can be feasibly built, not what might be politically expedient.
Illustration of all the new building types and whether they would be viable under the draft Model Code for typical lot sizes.
There is often a disconnect between how planners see development standards and how developers implement them. But ground truthing the code, when it is a draft, to understand the inevitable determinative impacts on the housing types that will get built, is the key to making the good development we want to see also the easiest to build.
Using a typical 5000 sf parcel zoned under the new code for 4 units, applying the FAR, we can build 4000sf. It becomes immediately apparent that many of the housing types we’re hoping for will never materialize and other types are going to yield less that then maximum number of units. Of the six types, I would expect the only feasible project is three townhomes. It is unlikely we’d generate very many 1000sf townhouses, 1200 sf triplex units or courtyard apartment buildings under the added cost of the IBC compliance.
The FAR needs to be up between 1 and 1.2 before we’d see the fourth townhome, or an apartment building.
4. Lean into making the most efficient and affordable housing form (small apartment buildings) the default infill Middle Housing type.
Our Spokane Six on the left works today, but wouldn’t be viable under the draft Model Code. This illustration shows that it would need to be 21% smaller.
Small apartment buildings have significant headwinds when it comes to financing, construction and operation. They also are the greenest, most efficient, context friendly and often least expensive forms of housing. They are also the best for preserving usable open space and landscape for large trees. They are the lowest common denominator building block for tackling the housing crisis. If the code works for those, then the other forms, like ownership townhouses, will work too.
When we tested our recent Spokane Grand sixplex, using the new Model Code, we discovered that we’d have to reduce the size by 21%, loose one of the porches, and downgrade the units from family friendly two bedrooms to one bedrooms. The pro forma for the development fell apart. If it can’t work in Spokane, with low land cost, reasonable construction cost, steadily climbing rents, there is very little chance these buildings would be viable in Puget Sound or other Tier 1 and 2 cities.
Without zoning incentives to build apartments, the market will continue to underproduce less expensive rental housing, even if we see some new ownership townhomes.
5. Reduce parking minimums.
Parking is always the cart that drives the horse. We have a housing problem not a parking problem.
So much has already be said and written about the high price of parking mandates, so I’m going to appeal to pure geometry.
On residential lots, designing for parking is step 1, before you even start to conceive of a building. For a sixplex on an alley, where parking is required, one space per unit arranged along the alley would require a lot width 56' feet minimum, which is wider than most urban lots. In order to provide the parking, much of the back yard is overtaken with pavement, more than 1/3rd of the site, lessening the quality of life for residents, creating stormwater issues and additional costs.
Without an alley, it is always worse; more than half of our typical lot is parking or driveway.
6. Regulating aesthetics on small neighborhood buildings is unnecessary micromanagement.
Strike this section. Or don’t. It is really so milquetoast that compliance isn’t an issue, but there will be lots of overlap/conflict with local codes that do regulate these simple aesthetics. Most townhouses are less that 20 feet wide — does a building’s design need to change every time there is a door? It is so fussy. In the interest of less bureaucracy, we should stamp out regulatory creep preemptively.
A Model Code that works.
The State’s Model Code is an opportunity to create a baseline for Middle Housing but it has to work. And this draft code would be so much more effective if it wasn’t second guessing its own mandate.
A final Model Code based on incremental increases of size over current single family structures, lot coverage not FAR, without parking minimums and design prescriptions, which allows builders the flexibility the make the homes people need, is the right direction forward for a statewide standard.
New sedge backyard cottage: 3 bedroom DADU
At 997 net square feet, the Sedge Cottage is a highly livable footprint that provides well-daylit space for living, necessary storage, flexibility on many sites, and two covered outdoor porch spaces. Within its compact form, the design features three bedrooms and two baths, a galley kitchen with a peninsula and plenty of storage. It features a bedroom and 3/4 bath on the main level that works well for an aging parent, as a guest room or work-from-home office. Standard, wood-frame construction, vented shed roof, slab-on-grade foundation, the careful placement of windows, and a simple exterior allow for low-cost construction without sacrificing durability, function, or style.
The design is under the height limit and can fit on the smallest lots, around trees, or on sloped lots, with space for adjacent parking if desired. The outdoor covered area is perfect for a BBQ and the cottage can be oriented toward the principal residence for multi-generational living around a courtyard. The front porch clearly marks the entry of the accessory dwelling.
The design targets 4-Star Built Green, with details for reduced air infiltration, energy-efficient heating, cooling, and water heating systems, passive solar heat gain in window/shading in summer, low-VOC finishes, no fossil fuel appliances, and all LED lighting.
See more at CASTcottages.com