As an AIA 2030 signatory firm, CAST has committed to its goal of carbon-neutral buildings by 2030. This Commitment is an actionable climate strategy that offers a set of standards and goals for reaching net zero emissions in the built environment.

Our design approach and process are thoughtful. We push the limits of sustainability through project performance by setting clear goals and making a positive impact on the environment. Our expertise helps our clients align with their green building goals and understand building life-cycle costs, lower utility bills, enjoy the benefits from natural light, and manage water usage.

The latest climate data tells us that reducing carbon emissions is not enough. To make the biggest impact, we must commit to net zero emissions by 2030—a path that requires strong, immediate action. Since the built environment creates a staggering 40% of the world's emissions, architects, engineers, and owners play a key role. We know that every project can be a catalyst for change.

Our Sustainability Action Plan includes principles and commitments that look for smart, innovative ways to deliver our projects and support climate goals.
Principles
Think Holistically
Act with Urgency
Every Project Counts
Make the Next Project Better

Commitments
Measure Performance
Support Research
Commit to AIA 2030 Challenge
Iterate on Success
Work with Partners
Advocate for Change
Celebrate Wins

See our Sustainability Action Plan here: www.castarchitecture.com/sustainability-action-plan

CAST is dedicated to tracking and reporting our progress toward the AIA 2030 Commitment. We will utilize energy modeling, life cycle assessments, and post-occupancy evaluations to measure operational energy use and embodied carbon across our projects. Our team will document and submit project performance data to the AIA Design Data Exchange (DDx), responding with transparency and accountability. By setting measurable benchmarks and analyzing trends, we will refine our strategies, improve outcomes, and contribute to industry-wide efforts to achieve carbon neutrality. Through this commitment, we will continuously push the boundaries of sustainable design while sharing insights that drive collective progress.

We have had deep roots in sustainable design since our founding in 1999. We are committed to improving the lives of individuals, families, and the community through vibrant and thoughtful design. CAST is at the forefront of sustainable architecture, creating high-performance buildings designed to endure. Our approach prioritizes responsible resource management throughout a building’s lifecycle, integrating climate-responsive design, the best available building science, and site-specific strategies.

CAST’s co-founder Matt Hutchins, AIA, CPHD, and Seattle Planning Commissioner talks about the major update to the Seattle’s Comprehensive Plan.
one seattle for all - 2025/02/08 10:37 PST – Recording

Seattle is growing (and that’s good)!

How do we make room for new housing and be the kind of city we want to live in?

Seattle’s Comprehensive Plan major update – a 20-year growth strategy.

-        Must include affordable housing and middle housing

-        Housing planning aligns with planning for transportation, utilities, climate and the environment, capital
facilities and parks/open space

Two kinds of affordable housing:
1. Subsidized and deeply affordable
2. Less expensive housing by size, type, and age (ie. ADUs, small apartments

-        Neighborhood centers can hold both types of affordable housing

-        Middle housing is less expensive and a great option

-        Urban Neighborhood housing types: single-family housing with ADU, duplexes, townhomes, stackedflats

We need more affordable housing – where does it go?

-        Neighborhood centers can support both types of affordable housing

Let your city council member know you support affordable housing, and you also support neighborhood centers and middle housing.
oneseattleforall.org

Wildfires have long been a reality for homeowners in the wildland-urban interface, but increasingly we’re seeing fires in more populated areas that aren’t traditionally considered at risk. During summers, smoke from distant fires now blankets urban areas causing smoke damage and indoor air quality issues. Fire seasons are now lasting longer. The National Fire Protection Association’s Firewise program is a great baseline for building in fire country, and CAST architecture regularly goes beyond designing residences resistant to climate change.

The Berm House in Washington’s Methow Valley uses hardscape to create a defensible perimeter, plus the majority of the exterior of the home is treated with flame-resistant shou sugi ban technique.

Defensible Site planning
The first layer of fire protection begins with the site itself. Design landscapes with defensible zones, creating clear, well-maintained spaces between the home and surrounding vegetation. Using fire-resistant plants, non-combustible materials like gravel or stone, and strategic placement of trees is pivotal to slow the spread of fire toward the house. The goal is fuel reduction—limiting the amount of flammable materials and vegetation around the home.

The selected materials and finishes at Bear Creek Base Camp in the Methow Valley include weathering steel panels which are highly durable, minimize maintenance, and are fire-resistant.

Fire-resistant envelope (roof, walls, eaves)
Choosing flame-retardant materials that can withstand high heat and resist ignition is essential. Specify exterior cladding like fiber cement panels, stucco, or brick, and opt for roofing materials such as metal, tile, or composite shingles. A simple, low-maintenance roof can be important. Windows can be designed with double or triple-pane tempered glass, which can withstand substantially higher temperatures than standard glass.

Icicle Creek Retreat (left) in the Wenatchee Forest has a concrete base set above the average snowfall line to protect siding and wood framing from the freeze-thaw zone. There is no exposed wood on the exterior to aid in fire protection.
The exterior of Isabella Ridge Escape (center) is clad in weathering steel panels that are durable, require almost no maintenance, and add a layer of fire protection.
The exterior of Wolf Creek Retreat (right) has a concrete base and pre-rusted weathering steel panels to aid in fire protection.

Minimizing venting
Make it airtight. Vents and openings are often weak points in fire-resistant design. Incorporating ember-resistant vent covers and tightly sealing gaps around eaves, doors, and windows can prevent embers from entering the home. Design a fire-resistant attic and crawlspace access points.

Buffer = Hardscape, not decks
Wind-blown embers generated during wildfires are the single biggest hazard. Use hardscaping around the home to create a defensible perimeter. This can include non-flammable elements like stone or brick pavers, retaining walls, concrete or metal planters, gravel paths, and water features.

Mechanical air filtration
As wildfires generate large amounts of smoke, ash, and fine particulates, incorporating air filtration into the home helps improve indoor air quality during wildfires. Ensure ductwork is properly sealed to prevent unfiltered air from entering the system.

Sprinklering
Integrating exterior fire suppression systems, such as eave misters, roof sprayers, perimeter sprinklers, water storage, redundant power, and remote control systems can add additional layers of protection.

Designing homes with layered fire protection is not just a consideration for rural areas—it is an essential strategy for resilience in an era of increasing wildfire risks. Thoughtful design may not only help protect individual homes but also contribute to the broader effort of creating safer, more resilient communities.

Accessory Dwelling Units (ADUs) and Detached Accessory Dwelling Units (DADUs) are transforming the housing landscape in urban areas. These self-contained small homes, can be attached or stand-alone and are becoming increasingly popular in cities grappling with housing shortages, rising costs, and shifting lifestyle preferences.

Help Housing Shortages
The surge in demand for housing has put significant pressure on urban neighborhoods, where space is limited and housing affordability is a critical issue. ADUs and DADUs offer a practical solution by increasing the housing stock within existing neighborhoods.

Affordability + Flexibility
ADUs and DADUs provide an affordable alternative for renters and homeowners alike. Homeowners can use these units as rental properties, offering housing at a lower cost than traditional apartment units. They can also serve as multi-generational living spaces, allowing families to stay connected while maintaining privacy. For many, ADUs are a way to downsize without leaving their neighborhoods, contributing to economic diversity in communities.

Ease Zoning Regulations
Cities across the US are revising zoning laws to encourage the construction of ADUs and DADUs. These policy changes make it easier for homeowners to build these units by reducing permitting costs, relaxing parking requirements, and increasing maximum allowable sizes. In Seattle, for example, pre-approved DADU plans streamline the process, saving time and money for homeowners.

Sustainability
These small homes align with urban densification goals. By utilizing existing infrastructure and minimizing the need for new developments these homes help reduce urban sprawl. Additionally, their smaller size typically results in lower energy consumption.

Enhance Community Character
Thoughtfully designed DADUs can blend seamlessly into existing architectural styles, adding diversity to the housing stock while preserving the integrity of the neighborhood.

See more: www.castarchitecture.com/backyard-cottages-new

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

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

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 Sitka Cottage: 3-bedroom DADU

At 1,000 net square feet, the Sitka Cottage features three bedrooms and two baths upstairs, an open living room and kitchen, storage, and an additional powder room tucked away on the first floor.  It fits flexibly on many sites with a walk-out terrace off the living room/kitchen. The three bedrooms upstairs are reasonably sized and work well for a family. Standard, wood-frame construction, vented shed roof, slab-on-grade foundation, 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 standard to small lots, around trees, or on sloped lots, with space for adjacent parking if desired. The cottage can be oriented toward the principal residence for multi-generational living around a courtyard. The front door is on the corner and can be placed on either the short or long side of the design, depending on site orientation.

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

Cross-Laminated Timber Berm House in Washington's Methow Valley

The Berm House is a private residence that doubles as the common house and gathering space for a 19 house mixed-income community in Washington’s Methow Valley. The house is set into the landscape, with a panoramic view of the farmland down valley, but hidden from the road by a berm that ramps up onto and across the roof. 

The south-facing building orientation optimizes winter solar exposure coupled with large overhangs to protect from snowfall and the intense summer sun. The home is post and beam structure with a cross-laminated timber (CLT) roof prefabricated in northeastern Washington. The design incorporates Passive House principles including managing seasonal heat gain from solar exposure, advanced air sealing, and mechanical ventilation. Thermal bridges are minimized by wrapping the house in continuous external insulation, including structural EPS under the foundation, isolating the home from outdoor temperature swings. The earthen roof adds thermal mass, wildfire protection, and a promontory to take in the down valley vista.

The great room portion of the house was designed for friends and neighbors to gather, share meals, and be a social center for the community. Off the great room, a five-foot wide hall leads to three guest suites and the primary suite. The uncomplicated and efficient floor plan shows a clear division between the private and public spaces. The mechanical room, pantry, storage, guest bath, and laundry spaces are arranged along the berm side of the house’s section.

The material palette is predominately warm woods. The CLT ceiling and glulam posts and beams were manufactured nearby, and a coffee table and kitchen bar were crafted locally from a fir tree felled on the property. The exterior employs the Japanese shou sugi ban preservation technique. The boulders throughout the site and as part of the berm were pulled from the site and placed by the owner. 

Team
Owner: Lee Whittaker
Methow Housing Trust
Architect: CAST architecture
Contractor: Methow Valley Builders 
CLT: Vaagen Timbers
Concrete subcontractor: JR’s Five Star Concrete
Geotechnical Engineering: GeoEngineers

See more here.

Seattle Architect pursues passive house certification with missing-middle housing on Lake Union

Echo on Eastlake apartments is pursuing Passive House certification, with early design and feasibility studies complete on the new 10-unit apartment building in Seattle’s Lake Union neighborhood.

This building will replace an existing 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. There is one central stair and no shared walls. And, the two homes on the ground floor are both fully accessible.

Six-to-twelve-plexes offer a superior urban experience, more housing units, more housing variety, and at least some fully accessible housing units. They also may preserve more tree canopy, increase open space, and optimize daylight compared to townhomes.

More to come in the months ahead.

TEAM
Developer: West Crescent Advisors, LLC
Owner’s Representative: Woodworth Construction Management LLC @woodworth_built
Architect: CAST architecture
Builder: Carrig Construction
Civil Engineer: Davido Consulting Group
Landscape Architect: Karen Keist Landscape Architects
Arborist:  Moss Studio
Geotechnical Engineer: Pangeo, Inc.
Surveyor: Terrane
Structural Engineer: Harriott Valentine Engineers
Envelope Consultant: B.E.E Consulting