Cottage Tower Cluster

Edit: Note about parking added below.

This cottage scenario has 16 cottages in four rows of four, with a central strip of common open space in the center, and 6′ walkways in the other spaces between the rows. Within each row, the cottages would be 2 feet apart (this assumes that both structures will be built with fire rated walls, which is not possible for a typical ADU being added alongside an existing structure). Each cottage uses the full 38′ height allowance. Cottages will have some storage for bikes, but only the front four cottages have any potential for driveway access.

(diagram to follow)

If there were an agreement from the residents to not park cars on the street (see the Culdesac Tempe car-free project), along with room for delivery trucks in the driveway space, you’d be able to mitigate impacts on the streetscape. Neighbors would still have loss of tree canopy and probable A/C exhaust and reduced natural airflow, as well as privacy concerns, and it could be a workout for emergency responders with so many stairwells (48 flights of stairs on a 10k sqft parcel).

Lot size: 75′ x 133.32′ = 9999 sqft 

Area inside setbacks: 65′ x 108.3′ 

Walkway widths 6′ 

Open space just in front and rear setback and common area (21.3 + 10 + 15)*75 = 3472 sqft, easily meeting the 20% requirement. 

Common open space requirement 16 units x 100 sqft each = 1600 sqft 

Common open space:21 1/3′ x 75′ = 1600 sqft 

Landscaped/nonimpervious portion of common open space – minimum 400 sqft

Building footprints 14.25′ x 18.66′ = 265.9 sqft 

Upper floor square footage: half 797.7 sqft, and others 853.7 sqft (with 1′ over hang from units along side boundaries)

Total upper floor area: 13,211 sqft, under the ~15,000 sqft allowed at 1.5 FAR

Note: By eliminating one 6′ walkway and 400 sqft of open space (new 16′ width), and making each of the remaining structures 3.75′ longer, you’d end up with 12 units that are over the 1.5 FAR, just counting the upper floors, by about 72 sqft, but then could use some of the storage allocation for the upper floors. 866sft avg on the upper floors. 

Storage on ground level; 265.9 sqft 

Lot coverage (allowed to be 45% exclusive of porches): 

265.9 x 16 = 4254.4 sqft 

Walkways along sides and across at two points 1976.4 sqft 

Walkways plus building footprints 6230.8 sqft (total impervious, with courtyard fully landscaped)

Minimum porch area: 6230.8 – 4500 = 1730.8 sqft 

1730.8/16 = 108.2 sqft porch per cottage

Could add another 769.2 sqft of impervious to the common open space, but then would need the porches to be 156.3 sqft each, and the storage at ground level would only be 109.6 sqft for each. 

With that scenario, with a 400 sqft strip of landscaping in the middle of the property, there’d be a total of 6230.8 + 769.2 sqft = 7000 sqft of impervious, which meets the 70% maximum. 

There is also a hose pull limit, normally 150′ from where the fire truck can park, which is often not adjacent to the property line if there is undeveloped right-of-way.  The distance to the farthest corner of a structure from the property line is about 150′ if using the side pathways and then going across rather than straight back, so it’s hard to predict whether you’d need sprinklers for the back row of homes. 

It is not clear what is needed to meet the requirement for cottages “on two sides” of the common open space. You might be able to reduce the cottage count by one on a rear back corner, and then count part of the rear setback (15 feet) toward the open space requirement, eliminating the open space in the middle and allowing more optimized use of the FAR and bonus storage space allotted. I think this is very undesirable because it could mean that all the cottages in the middle rows are looking right into their neighbors’ windows, instead of being separated by 21 feet of open space and the potential for trees there.

In less than 18 months, based on SB 5184, if these cottages are less than 1200 sqft, Bellevue will not be able to require any parking for them, no matter how far from transit they are, though they’d still get the 300 sqft each for use as unheated storage.