Seattle - Layout
We began layout by assessing what the zoning laws would allow. Our existing building was only one foot from the required setback in the front (east), and only about seven feet in the back (west). On both sides we could go out quite far (to the North and South), and we could go up to two and a half stories. Unfortunately, if we put any significant addition to the north, we would begin to create severe shading of the neighbor's house, and if we went up would we also shade the neighbor's house, but not as badly. Although code would allow us to build up to 35 feet high (including a pitched roof) and only five feet from the neighbors property line, we could clearly significantly shade their house, and although we don't know them, it was important for us to avoid shading them as much as possible.Since we decided we wanted an ADU (apartment, see needs), figuring out where to put it was our first concern in layout. Size wise, we wanted it to be a one bedroom unit, of about five to six hundred square feet: plenty for one person and workable for a young couple. Since our space requirements looked to be about 1500 square feet, that meant the ADU would be about one quarter of the building. ADU's are often in basements, but since the building had no existing basement we ruled that out (and even if it did, the lot is very level, so getting light into the basement would be hard). Another alternative is on the second floor, but that led to complications due to both the code requirement that the ADU door be not in front, so locating the stairs was hard, and it made fitting the other 1500SF a challenge. If the stairs to the ADU would be inside the house, we'd either need two sets of stairs, or a way to share a stairway. Two sets of stairs would waste too much space, and although we could locate our offices upstairs and the main house downstairs, we just couldn't come up with a good layout with shared stairs (maybe we didn't try hard enough?). Another alternative was to use external stairs, but we didn't see that as being aesthetically appealing so we didn't pursue that path. Essentially it was easier to put the ADU on the main floor.
Along with placing the ADU, we worked on what the footprint of the house would be. Based on passive solar principals, the house should be long on the E-W axis, and preferably not too deep on the N-S axis. This is also good for getting good daylight into the house. Unfortunately the existing house was 30'6" on the E-W and 32' on the N-S, and zoning laws would only let us go 8 more feet in the E-W direction: one foot in the front and seven feet in the back. We had no desire to extend to the N due to wanting to avoid shading the neighbor as much as possible, nor did we want to extend to the S, since that is the best outdoor space on the lot. With the ADU and our public space occupying the main floor, extending seven feet out to the W made the most sense, and otherwise trying to stay within the footprint.
With the footprint decided (including leaving the existing porch), the ADU ended up running E-W on the north side of the main floor, with no real southern exposure. While this is certainly not ideal (and maybe we will regret it someday), it made everything fit and kept us from having to sacrifice sunlight in our part of the house. Renters always seem to get sub-optimal conditions. To compensate, we first added a loft to the ADU on the east face, with a south window looking over the porch, but when we decide to have both a guest room and a guest bathroom, the loft disappeared and we replaced it with a big bay window on the east, allowing for a little south light (conveniently, code allows bay windows to project up to two feet beyond the required setback). Later, we would use windows and skylights to make sure the ADU got the best light in the situation. More disappointing was that there would be no way the ADU could get any passive solar gain.
This now left our part of the house with minimal space on the main floor and almost too much space on the second floor (which is partly to explain why the guest room, guest bathroom and art studio got added). Also when we went to layout the ADU, the space didn't accommodate a decent kitchen, so we ended up putting its kitchen in a 7'6" by 10' bump out to the north, which we put a lower slope shed roof on, hopefully making it virtually invisible to the neighbor (whose floor is about three feet higher than ours. Also they have a six foot fence on the property line).
To see the final first floor plan click here.
To see the final second floor plan click here.
Ignoring the problem of placing the ADU, the design patterns that affected us most were:
It was important to us that the house "feel good". This may be a strange concept to some, but we believe that there is a feel to a house, and anyone who is willing to pay attention to it can tell the difference. Although we believe the house will feel good, we won't really know until we've lived in it for a while. Design is all about anticipating the future, and how you use your current house may not be completely indicative of how you will use another house. Like all designs, we made a lot of compromises, and there were things we wish we could find a better way to do. But at some point, you have to stop thinking about it and just build it (besides, the architectural fees get really expensive).