GPAHG ADU Case Study Comparison - Making Housing and

GPAHG - ADU Comparative Study - 1

Date: December 11, 2017

From: Philip Burns, Greater Pasadena Affordable Housing Group

To: Pasadena City Council

Subject: Comparative Study of Impacts of Existing ADUs in Pasadena - REVISED -

Executive Summary

Dear Councilmembers:

As the City is reconsidering its 2003 law which severely limited the ability of single-fam-ily homeowners to develop Accessory Dwelling Units (ADUs) on their properties, Coun-cilmembers must consider the issue from a number of perspectives, among them care for the elderly, availability of housing, and social equity. Representatives of neighborhood groups have also rightly claimed that the effect of Accessory Dwelling Units on neighbor-hood character is also a consideration. With that in mind, the Greater Pasadena Affordable Housing Group (GPAHG) set out to examine the potential impacts of ADUs on neighbor-hood character.

This study compared three pairs of similar, adjacent neighborhoods in the City of Pasadena which differed in the number of Accessory Dwelling Units in them. GPAHG evaluated the impact of these ADUs on neighborhood character, property values, traffic and parking and found no significant impacts. Therefore, we conclude that the effect of future ADUs on single-family neighborhoods in Pasadena will likely be minimal. Given the urgent need to create lower-cost and lifecycle housing in the City, encouraging ADU construction would seem to be a good policy in the furtherance of the City’s goals.

Background

The City of Pasadena already has approximately 740 legal non-conforming* Accessory Dwelling Units. Thus we are able to estimate the future impacts of ADUs on neighbor-hood character by comparing neighborhoods which currently have few ADUs to those which have many. Seeking to find pairs of very comparable neighborhoods or streets only differentiated by the presence of ADUs on their street, we settled on the neighborhoods shown in Figures 4, 5, and 6. The two neighborhoods in Figure 4 are located immediately adjacent to each other and are within the same boundary streets of Hill, Washington, Allen

* Non-conforming under the 2003 law; some of these units may now be legal per the 2017 law. Some of these units may also be non-conforming duplexes rather than ADUs.


Marengo AvenueHigh-ADU Street

Garfield AvenueLow-ADU Street

Primary Dwelling Units 86 83% 87 98%

Accessory Dwelling Units 10 17% 3 2%

Total Housing Units 96 90

Figure 2. Number of Housing Units in the District 1 Study Area.

Wesley AvenueHigh-ADU Neighborhood

Dominion AvenueLow-ADU Neighborhood





El Molino AvenueHigh-ADU Street

Madison AvenueLow-ADU Street





Study Areas

and Mountain, in Council District 2. Both are zoned RS-6, neither is a Landmark District, and each has 7,500 square foot lots. The two streets in Figure 5 are located adjacent to each other in District 1, in the northwestern part of Pasadena between Howard Street to the south and the City of Pasadena Boundary to the north. The two streets in Figure 6 are located adjacent to each other in District 7, in the southern part of Pasadena, within the boundary streets of California Boulevard and Alpine Street.

Figures 1, 2 and 3 show the number of single-family homes and ADUs in each study area.


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Study Areas for ADU Neighborhoods Comparison

City of Pasadena Boundary

High ADU Neighborhood

Low ADU Neighborhood

Figure 5

Study Areas

Block for Parking Counts

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Figure 5

Study Areas

Block for Parking CountsDistrict 1

Study Area


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Figure 6

Study Areas Block for Parking Counts

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Figure 5

Study Areas

Block for Parking CountsDistrict 7

Study Area


Figure 8. Low ADU Neighborhood. Dominion Avenue between Washington and Asbury.

Figure 7. High ADU Neighborhood. Wesley Avenue betwen Asbury and Whitefield.

We compared these two neighborhoods in terms of the following characteristics:• Neighborhood Character/Visual Impact• Property Values• Traffic• Parking

District 2 Study Area


Figure 10. Low ADU Street. Garfield Avenue between Dearborn Street and Highland Street.

Figure 9. High ADU Street. Marengo Avenue at the intersection with Tremont Street.

We compared these two streets in terms of the following characteristics:• Neighborhood Character/Visual Impact• Property Values• Parking



Figure 12. Low ADU Street. Madison Avenue between Fillmore Street and California Boulevard.

Figure 11. High ADU Street. El Molino Avenue between Cornell Road and California Boulevard.

We compared these two streets in terms of the following characteristics:• Neighborhood Character/Visual Impact• Property Values• Parking



Figure 13. Close-up of Dominion Avenue. There are no ADUs on the lots visible in this image.

Figure 14. Close-up of Wesley Avenue. There are two ADUs on the lots visible in this image.

Neighborhood Character/Visual Impact

As Figures 7 - 12 show, from a casual drive down the street, the presence of ADUs is not noticeable. Setbacks, building heights and building modulation are unaffected by the pres-ence of ADUs. Any differences in character are due to architectural styles, tree canopy and other issues unrelated to the ADUs.

Figures 13 - 18 show closer views of houses on Wesley and Dominion Avenues, Marengo and Garfield Avenues, and El Molino and Madison Avenues viewed at an oblique angle. Again, the ADUs are not visible and do not play a role in the visual character of the neigh-borhoods.


Figure 15. Close-up of Garfield Avenue. There are no ADUs on the lots visible in this image.

Figure 16. Close-up of Marengo Avenue. There are two ADUs on the lots visible in this image.


Figure 17. Close-up of Madison Avenue. There are no ADUs on the lots visible in this image.

Figure 18. Close-up of El Molino Avenue. There are two ADUs on the lots visible in this image.


1 2

3 4

5 6

Figure 19. District 2 Study Area ADU Examples.

Figure 19 shows ADUs located in the study areas, or immediately adjacent in Bungalow Heaven. ADUs are generally hard to spot; however, with a direct view down the driveway, most ADUs are visible from the public right-of-way. (3) and (6) are exceptions, where the ADUs are screened by a fence. (3), a property within the Bungalow Heaven National His-toric Register District, is an example of a historically sensitive screening of an ADU. (1) is an example of a carriage house, or above-garage ADU. The images show a variety of archi-tectural styles and varying levels of attractiveness, largely depending upon the architectural distinction of the main house and the level of upkeep of the property over time.



1 2

3 4

5 6

Figure 20. District 1 Study Area ADU Examples.

Figure 20 shows ADUs located in the study area, along Marengo and Garfield Avenues. ADUs are generally hard to spot; however, with a direct view down the driveway, some ADUs are visible from the public right-of-way. In (3), an attached garage was converted into an ADU. In (4) the side and back yards are screened off, hiding the ADU completely. The images show a variety of architectural styles and varying levels of attractiveness, large-ly depending upon the architectural distinction of the main house and the level of upkeep of the property over time.



1 2

3 4

5 6

Figure 21. Study Area ADU Examples.

Figure 21 shows ADUs located in the study areas, along El Molino and Madison Avenues. ADUs are generally hard to spot even looking down the driveway; as most are either screened off by trees or located directly behind the main home. (1) and (3) are some ex-ceptions, where (1), has a gate screening off the ADU making it less visible, and (3) where the ADU is a two-story structure and can clearly be seen from the street but is slightly screened off by foliage. The images show a variety of architectural styles and varying levels of attractiveness, largely depending upon the architectural distinction of the main house and the level of upkeep of the property over time.



Property Values

GPAHG compared recent property sales between the three areas in order to determine whether there might be an effect of ADUs on property values of adjacent single-family homes. It is easy to surmise that ADUs increase the property values of the properties on which the ADU is located; the additional living space and income potential of the ADU clearly increase the overall property’s worth. However, some residents may fear that ADUs decrease the overall desirability of the neighborhood, as reflected in property values of adjacent single-family homes with no ADUs.



Total Per SF Total Per SF

Recent Average Sales Price $705,250 $442 $657,500 $454

Percent Difference com-pared to Low-ADU Nhood. +7.2% -2.6%

Number of Sales 24 8

Figure 22. Home Sale Value Comparison - District 2 Study Area. Comparison of sales prices of homes with no ADUs within the past three years.

Marengo AvenueHigh-ADU Street

Garfield AvenueLow-ADU Street


Recent Average Sales Price $583,000 $481 $554,900 $473

Percent Diffrerence com-pared to Low-ADU Nhood. +5.1% +1.7%

Number of Sales 5 5



El Molino AvenueHigh-ADU Street

Madison AvenueLow-ADU Street


Recent Average Sales Price $2,363,322 $760 $2,257,125 $680

Percent Difference com-pared to Low-ADU Nhood. +4.7% +11.7%

Number of Sales 5 4


Figures 22 - 24 demonstrate that there is no major difference between the streets in the value that buyers assign to them. Actually, the recent average sales prices are higher in the areas with ADUs than those without them.

Thus it would be very difficult to conclude that ADUs have a generalized negative effect on neighborhood sales prices. Prospective buyers appear to value the neighborhood charac-ter of areas with ADUs similarly to areas without them.


Asbury & WesleyHigh-ADU Neighborhood

Asbury & DominionLow-ADU Neighborhood

AM Peak PM Peak AM Peak PM Peak

Southbound Through 7 9 N/A N/ASouthbound Right 17 14 16 14Southbound Left 6 7 12 9Northbound Through 2 4 N/A N/ANorthbound Right 1 1 N/A N/ANorthbound Left 3 2 N/A N/AEastbound Right 5 0 N/A N/AEastbound Left 2 8 4 5Westbound Right 3 4 9 8Westbound Left 0 2 N/A N/A

Total 46 51 41 36Total - Adjusted for 3-Way Intersection 46 51 55 48

Figure 25. District 2 Traffic Study.

Traffic

GPAHG went to the District 2 Study Area and conducted simultaneous traffic counts at Asbury and Wesley (high-ADU neighborhood) and Asbury and Dominion (low-ADU neigh-borhood). These traffic counts took place on Monday, May 22, from 5:50 to 6:50 pm, and Wednesday, May 24, from 7:45 to 8:45 am. The results of the traffic study are presented in Figure 25. The Eastbound Through and Westbound Through movements are omitted because they correspond to through traffic, not traffic related to the comparison streets of Wesley and Dominion Avenues.

Traffic levels on the two streets are very low, with less than 60 cars per hour (one car per minute) making a movement onto or off of Wesley or Dominion Avenues. This compares to a local roadway capacity of 600 vehicles per hour. Volumes are slightly higher at Asbury and Wesley, but when accounting for the fact that Asbury and Wesley is a 4-way intersection, as opposed to the 3-way intersection of Asbury and Dominion, that difference disappears.


It is reasonable to conclude that in general, ADUs increase the number of trips in an area; residents do need to commute out of the area by some means. However, the increase in trips is minimal compared to the capacity of the roads. For example, if each of the eight ADUs on Wesley Avenue between Whitefield and Asbury created three daily trips, they would add only 24 daily trips to the street.

This small number of trips compared to the capacity of the roads also applies to the other study areas; therefore, traffic studies were not conducted for the other study areas.

Parking

GPAHG surveyed evening parking conditions in each of the three study areas, in order to determine whether ADUs created a parking crunch in the area.

Figure 26 compares parking utilization on Dominion and Wesley Avenues in District 2. On-street parking utilization was low on both streets. However, it was higher on Dominion Avenue than on Wesley Avenue. This is likely due to the commercial uses at the north end of Dominion Avenue at Washington Boulevard. The ADUs on Wesley Avenue did not have a large effect on on-street parking.

Figure 27 compares parking utilization on Marengo and Garfield Avenues in District 1. The total amount of cars on each street is similar. Due to the fact that Marengo has on-street parking on one side only, the percentage utilization is higher. However, it is still only 40% occupied.

Figure 28 compares parking utilization on El Molino and Madison Avenues in District 7. There were more cars present on Madison, the low-ADU street.

While it is reasonable to conclude that ADUs will generally increase the demand for on-street parking, it is highly doubtful that this effect will be very strong. Furthermore, since in the majority of Pasadena’s single-family neighborhoods, overnight parking is prohibited, there is a large supply of available on-street parking throughout the day.




Vehicles Parked 11 19

On-Street Parking Capacity 60 64

On-Street Parking Utilization 18% 30%

Figure 26. District 2 Parking Study. Conducted at 7 pm on Monday, May 22 on Wesley Avenue between Asbury and Whitefield, and on Dominion Avenue between Washington and Asbury.

Marengo AvenueHigh-ADU Neighborhood

Garfield AvenueLow-ADU Neighborhood




Figure 27. District 1 Parking Study. Conducted at 7 pm on Wednesday, December 6 on Marengo and Garfield Avenues between Howard Street and the city limit.

El Molino AvenueHigh-ADU Neighborhood

Madison AvenueLow-ADU Neighborhood




Figure 28. District 7 Parking Study. Conducted at 6:30 pm on Wednesday, December 6 on El Molino and Madison Avenues between California Boulevard and Alpine Street.

Documents

GPAHG ADU Case Study Comparison - Making Housing and