Blog #08 : FAR Restrictions

In 2018 our city enacted a rule that aimed to prevent “McMansions” or other single-family homes that consume the lot that they sit upon, called the FAR Rule.

What is the FAR rule for our city?

The FAR limit, short for “floor area ratio”, defines the total square footage allowed in your home based on the square footage of the lot you’re building upon. In our city, the FAR limit is 0.50. This meant that if our lot was 5,000 sq. ft, our home could not be greater than 2,500 sq. ft. above the ground. While 2500 sq. ft would already be 35% more space over our current home, as well as a layout that suits our wants more, it didn’t make financial sense to build. We needed to understand these rules more deeply and started reading.

Exceptions to the FAR restrictions

Our city provided the below exceptions to the FAR restrictions:

1. All stories, or portions or stories that are underground did not count towards the FAR sq. footage.

2. Portions of the home that are not greater than four feet (4’) above ground level did not count towards the FAR sq. footage. E.g. basements do not count towards the 2500 sq. ft as long as they are not 4 feet above ground. But if a portion of the basement is 4 ft above ground, that portion will be included in the 2500 sq. ft.

Image from seattle.gov

3. Either up to 500 additional square feet of floor area in any accessory structure that is an attached attached accessory dwelling unit (AADU) also called a mother-in-law unit, but attached to the home, or up to 250 square feet of floor area in an attached garage.

How did we meet the FAR Restrictions?

An underground basement sounds great, but there is a huge cost - digging in dirt is expensive in the city. We’ll get into just how expensive moving dirt around in a city actually is, but unless you’re ready to spend the money: avoid digging as much as you can. Seriously.

In our case, since we were looking at a sloped lot, part of the basement was going to be 4 ft above ground making it a daylight basement. We wanted the extra space so in our designs we designated the part of the basement that was above 4 ft. above ground as an AADU. Labeling our basement as a AADU gave us an additional 500 sq. ft. Fortunately we were already considering a separate unit for our parents with a bedroom/office for the basement, with its own bathroom and a wet bar. To accommodate AADU requirements we made few changes to our plans.

• We extended the wet bar area to a full kitchen.

• We made sure the basement was independently accessible including a way to lock access from the rest of the house.

• Designed the ceiling and walls to be fire rated.

The additional kitchen and extra insulation comes with a cost, but this meant that we had another income source in the future if we wanted to rent the basement out.

Learnings: You don’t get to just claim this sq.ft for AADU. You have to be thoughtful in your design. AADU restrictions likely apply differently based on where you are building, so definitely invest the time in learning it yourself or hire someone that can explain it to you and help you with ideas.