Is Bellevue the best place for two homes on one lot?

Edit: See info about Kirkland inside post

Here are some reasons builders might choose Bellevue if they’re looking to put two homes on one lot. 

In Seattle, you don’t get a reduction in setbacks until you put three homes on a lot, but in Bellevue, you only need to build two homes to get the “Middle Housing” setback reductions of 10’ to the front and 10’ to the back, plus side setback reductions in some cases. If each home is 60’ wide and three stories tall, that could be an extra 1800 square feet of potential building size for each, and it’s not uncommon for new construction here to sell for upwards of $1000/sqft. 

FAR allowances in Bellevue wouldn’t necessarily allow you to maximize your use of that area, but unlike many other cities, we don’t count the ADUs toward that allowance (see page 12), and we give each home and each ADU an extra 300 sqft that may be used for storage or garage space. ADUs are allowed to be at least 1200 sqft, but can exceed that if they are all on one level. 

Redmond has a payment-in-lieu to provide funds for affordable housing, and in 2027 it will be $30 per sqft, starting at the first unit. If there are two 3000 sqft homes and two 1500 sqft ADUs on a lot that’s approximately 10k sqft, the Redmond homes will be $270k more costly to build (though Redmond’s fees are lower in 2025 and 2026 as the policy is ramped up). 

Separately, Bellevue also has special provisions for cottages that allow much greater lot coverage and impervious surface than other middle housing. While it does not maximize the buildable potential, it would be possible to put two single-level cottages on a parcel, creating lovely homes that are great for aging in place. The main limitation is that each cottage can be no more than 1500 sqft of floor area plus 300 sqft of bonus space. For cottage developments, there is a common open space requirement, but most of this can be met by the driveway (Bellevue might be the only place that allows driveway to be used toward this requirement, and it is also unusual that there is no requirement that porches face toward this common open space), and the ceilings could be quite high as long as they stay under 24’ above average existing grade and mostly under the 18′ maximum above which they’d be counted as a second story. 

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Kirkland:

As part of Kirkland’s O-4905 ordinance for middle housing, a payment-in-lieu of $15/sqft for all square footage over 2000 square feet per unit will raise money for affordable housing, and this will take effect January 1, 2027 (see page 96 of the ordinance). 

In comparison with the scenario for Redmond, it looks like this would only be $15k for each of the homes with 3000 sqft, so a much more moderate financial impact, but with the potential to raise meaningful funds for affordable housing. I see some coverage that describes this as closing the “McMansion loophole,” and it does seem that it will incentivize ADUs (Kirkland allows two ADUs up to 1200 sqft) and middle housing under 2000 sqft, which would not be charged this fee at all. At least for cottages, the garage is not counted toward the gross floor area, but the garage does count toward the Floor Area Ratio (FAR), so you’d need to look more carefully at what is counted toward that 2000 sqft if you were designing a project.