This is a design for a multigenerational home for three generations of the same family who want to live in a house together. It is designed to meet the Passivhaus standard. The house will accomodate two older parents and their three adult children as well as their partners, and (so far) one grandchild, and possibly a grandmother. There are four suites in the house–one on each corner of the house, one for each couple. Each suite has a sitting room with a kitchenette, two bedrooms, a Japanese bath and laundry downstairs, and a conventional bathroom upstairs. Everyone shares a large multi-cook kitchen, Great Room and Media Room on the ground floor, and a game room and multi-purpose rooms (craft, computer, kids’ play and exercise rooms) on the second floor, as well as a separate garage and shop space, and the garden. The multi-purpose rooms open onto the second floor mezzanine, and have a similiar relationship to the shared space as the sitting rooms on the ground floor.
My clients first hired me to help find a site for the house. Working with realtor Danielle Johnson, we identified a number of possible locations and reviewed them for suitablity for the project, finally settling on two adjacent parcels at 90th and Palatine in the Greenwood neighborhood. It was perfect (high walkscore, almost flat, reasonable price, alley access) except for the layer of peat that resides five feet down below much of the neighborhood, remnants of an ancient bog. We did a quick feasibility study which was favorable, my clients purchased the site, and we began our design.
Though multigenerational housng–several generations of a family living in the same house–is common in other parts of the world, it is a new building type in Seattle. Our first task was to find an architectural expression of the way our clients wanted to live in the house. It’s a bit of a blend of a single-family house and co-housing. However it is much smaller in scale than most co-housing, and sharing a house with your adult children and their spouses and their children suggests a different approach to privacy than living in a house with your children when they are children. Everyone wanted some degree of autonomy and privacy.
We worked closely with the contractors, bouncing ideas off of them along the way to keep the price within range, and the assemblies ones that have worked for them in their projects in the past. The peat beneath the surface of the site in Greenwood proved challenging. In conversations with structural engineer Carissa Farkas, civil engineer Chris Webb and pile contractor McDonnell Pile, and with analysis from a corrosion engineer, we learned that due to the acidity of the peat, steel pin piles could corrode to the point of structural uselessness in as little as nine years. We went with an auger-cast concrete pile and grade beam system, to provide a foundation that would be sure to last the 100+ year intended life of the house.
- There are eight bedrooms and one kitchen. Each suite has a wet bar, as does the Game Room.
- The house and landscape are fully accessible and adaptable, designed for aging-in-place. There is an elevator. My clients expect to live in the house the rest of their lives.
- The structure itself has been designed to last 100+ years.
- The house meets all of the requirements for Priority Green (Water Sense, green storm water infrastructure, recycling rate, etc) except it is larger than a typical single-family house.
- 44% of the house’s interior area is shared space. (Not counting the garages and workshop, which are shared as well.)
- Each of the four two-bedroom suites (one for each couple) are about 1,100 SF each.
- Parking provided was in excess of single-family zone requirements.
- All setback height and lot coverage aspects of the design conformed to single-family zone requirements.
- The design and level of finish of the house itself is very modest. The initial ballpark estimate was $150/SF for the house itself.