SB 9
BACKGROUND DATA ON LOT SIZE
and
BUILDOUT SCENARIOS
For purposes of understanding lot sizes in Sunnyvale, the following table shows the approximate number of lots within specific size ranges for the R-0, R-1, R-1.5, R-
1.7/PD, and R-2 zoning districts:
Zoning
District
Under
5,000 sf
5,000 –
5,999 sf
6,000 –
6,999 sf
7,000 –
7,999 sf
8,000 –
8,999 sf
9,000 –
9,999 sf
10,000
sf and
more
R-0 101 5,000 7,837 1,744 641 463 372
R-1 11 2 185 1,062 1,861 770 660
R-1.5 85 47 19 7 0 0 5
R-1.7/PD 136 0 0 0 0 0 0
R-2 1,875 377 555 309 211 58 220
Total 2,208 5,426 8,596 3,122 2,713 1,291 1,257
Potential Build Out Scenarios for DUOH Developments without an ULS Next, the table directly below shows some scenarios of what the total FAR would be if 45 percent, or 55 percent if findings are met, for various lot sizes with the addition of ADUs on lots that do not take advantage of the ULS. For discussion, staff is showing the maximum FAR if the applicant develops the site to the maximum that must be allowed. For the following scenarios, staff is assuming that the applicant is developing on a vacant site or has proposed to remove the existing single-family dwelling.
Total FAR (w/
ADUs) at Base
45%
Total FAR (w/
ADUs) at Base
55%
Lot Size
(sq. ft.)
45%
FAR in
sq. ft.
55%
FAR in
sq. ft.
ADUs
(max
sq. ft.
allowed)
sq. ft. % sq. ft. %
5,000 2,250 2,750 1,600 3,850 77% 4,350 87%
6,000 2,700 3,300 1,600 4,300 72% 4,900 82%
7,500 3,375 4,125 1,600 4,975 66% 5,725 76%
Attachment 6
9,000 4,050 4,950 1,600 5,650 63% 6,550 72%
It is important to note that these are the most extreme examples and on many smaller lots it is likely not possible, or desirable, to build to the maximum. But, because the City is required to allow the ADUs, even if the FAR is already at the maximum, it is important to detail these worst-case scenarios so that the Planning Commission and Council can fully understand what a 45 percent and 55 percent FAR base could generate.
Potential Build Out Scenarios for DUOH Developments with a ULS When an ULS is proposed, the legislation is much clearer that only two units are allowed on each new lot. This makes the FAR calculations slightly easier to demonstrate if we assume that each of the new lots is developed with two DUOH units and no ADUs. In these scenarios, it is also assumed that the lot would be vacant, and the existing single-family dwelling would be removed for the new development. On the smaller lots, it is assumed that the two new units on each lot would be at least 800 sq. ft. each as that is what the City is required to allow based on the legislation, this means on smaller lots, the base FAR of 45 percent, and higher FAR of 55 percent, may be exceeded as reflected in the table.
45% FAR on each new
lot
55% FAR on each new
lot
Original
Lot Size
(sq. ft.)
New Lot
Size (50%
Assumed)
sq. ft. % sq. ft. %
5,000 2,500 1,600 64% 1,600 64%
6,000 3,000 1,600 53% 1,650 55%
7,500 3,750 1,688 45% 2,063 55%
9,000 4,500 2,025 45% 2,475 55%
As shown in the table above, the lot FAR for each of the new lots is lower under these assumptions than in the scenarios where no ULS is proposed. It is likely with the ULS type of DUOH development the existing single-family dwelling would need to be removed in order to accommodate the new development and lot split. However, if an existing single-family dwelling was retained, the FAR allowances may be higher overall than what is shown above.
Potential Build Out Scenarios for DUOH Developments on Lots with an Existing Single- family Dwelling without an ULS
Lastly, the next table shows what FARs could look like on sites where the existing single-family dwelling is retained, no ULS is proposed, and the maximum sq. ft. of ADUs is also proposed. Existing single-family dwellings range in FAR significantly, so for this Attachment 6
example staff has chosen to assume existing FARs of 35 percent, 45 percent, and 55 percent. It is important to remember that if a lot is already developed at an FAR over the maximum allowed by the Sunnyvale Municipal Code, the applicant is still entitled to build a second DUOH unit of at least 800 sq. ft. and two detached ADUs of 800 sq. ft. each (1,600 sq. ft. total).
Existing House Size Total FAR
Lot Size % s.f. New
DUOH
Unit
Two
ADUs
s.f. %
5,000 s.f. 35% 1,750 800 1,600 4,150 83%
45% 2,250 800 1,600 4,650 93%
55% 2,750 800 1,600 5,150 103%
6,000 s.f. 35% 2,100 800 1,600 4,500 75%
45% 2,700 800 1,600 5,100 85%
55% 3,300 800 1,600 5,700 95%
7,500 s.f. 35% 2,625 800 1,600 5,025 67%
45% 3,375 800 1,600 5,775 77%
55% 4,125 800 1,600 6,525 87%
9,000 s.f. 35% 3,150 900 1,600 5,650 63%
45% 4,050 800 1,600 6,450 72%
55% 4,950 800 1,600 7,350 82%
Again, it is highly unlikely that applicants on the smaller lots would want this level of density on their property as it would not allow for much yard space or privacy between units. However, because it is possible that someone may develop a small site to the maximum, staff wanted to include those scenarios. It is also important to remember that staff can use objective development and design standards to control development, but only to the extent that we allow the minimum 800 sq. ft. DUOH unit and the two detached 800 sq. ft. ADUs. Therefore, it is likely that in the higher FAR scenarios on the smaller lots, multiple development standards may need to be waived to accommodate this level of density which could lead to taller structures, no yard space, and less opportunity for privacy landscaping between properties.
Attachment 6