A GUIDE TO BUILDING IN THE HILLS OF LOS ANGELES

Article #10: 809 Higgins St – Final Design

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We are working through the Baseline Hillside Ordinance to determine what we can build at the fictional property, 809 Higgins St. in the Hollywood Hills.   In the preceding articles of this series, we went over 6 items in detail:

1. Lot (summary of project)
2. Setbacks
3. Residential Floor Area (RFA) & Slope Band Analysis
4. Height Limits
5. Lot Coverage & Grading
6. Retaining Wall

In addition to the above, there are requirements concerning Parking, Fire Protection, Street Access, and Sewer Connection (Article #9).

This article provides a summary of the 6 major requirements that must be met to arrive at the final solution:

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1. Lot

The fictional property is at 809 Higgins Street in the Hollywood Hills:

1. 2,500 SF Parcel
2. 25’ wide by 100’ deep
3. Lot was purchased with an older residence and demolished to make way for new construction
4. Lot fronts a Substandard Hillside Street
5. Zoning: R-1-1, and subject to Baseline Hillside Ordinance

2. Setbacks

The zoning code requires each side of your home to be set back a certain distance from the property line.   The standard setback requirements for each yard of R-1 zoned residences are:

FRONT YARD	– No less than 20% of Lot Depth- No more than 20 feet
SIDE YARD	– No less than 5 feet- No restriction on maximum setback- The required side yard may be reduced to 10% of the Lot Width, but if the lot is less than 50 feet wide, it cannot be reduced to less than 3 feet- For structures with a height greater than 18 feet, one additional foot must be added to each required side yard for each increment of 10 feet above the first 18 feet.
REAR YARD	– No less than 15 feet- No restriction on maximum setback

Since we are on a Substandard Hillside Limited Street, the following additional provisions apply:

• “For Lots fronting on a Substandard Hillside Limited Street, in no event shall the Side Yard be less than 4 feet.”
• “For buildings or structures with a height greater than 18 feet, one additional foot shall be added to each required Side Yard for each increment of 10 feet or fraction thereof above the first 18 feet.”
• For lots fronting Substandard Hillside Limited Streets, the Front Setback can be 5′ if the prevailing setback allows. 

We need to maintain the building height at less than 28 feet in order to keep the 4’ side yard setback.

We now can compile all of the above into a single diagram showing the Front, Side, & Rear Yard Setbacks and the Buildable Zone. The Buildable Zone is 17 feet wide by 80 feet long, or 1,360 square feet.

3. Residential Floor Area (RFA)

Residential Floor Area (RFA) is the total area in square feet measured from the inside of the walls of the building. Stairs are counted only on one level. Up to 250 SF of porches, patios, breezeways, and exterior walkways are not counted in the RFA calculation. Up to 400 square feet of parking and basements are not counted either.

There are two ways to determine the maximum RFA that is permitted for your property. One is with the Slope Band Analysis and the other is to utilize the Guaranteed Maximum Residential Floor Area provision of the code.

At 809 Higgins Street, approximately half of the site is flat from the previous home, and the other half is a steep slope held back by an existing retaining wall.

What is our maximum RFA? Lets check using both the 1) Guaranteed Maximum RFA and 2) Slope Band Analysis methods:

1) Guaranteed Maximum Residential Floor Area

Decide if the allowable area (either 25% of the lot size or 1000 SF) is enough to satisfy your program requirements. Your decision will take into account the RFA bonus which adds 30% to the total allowable area by utilizing one of the 7 given design options – thus effectively allowing at least 1300 SF of program.

2)  Slope Band Analysis

A formal slope band analysis will need to be submitted by your land surveyor, but you can do a preliminary back-of-the-napkin analysis as part of your discovery process.

The back-of-the-napkin analysis is as simple as drawing a section or two through the site to find out the prevailing slope, and do ballpark calculations to check against the given tables in the Baseline Hillside Ordinance.   If it is obvious that the allowable area per the topographical map would be less than the 1000 SF (1300 using the 30% RFA Bonus) allowable by the Guaranteed Maximum RFA provision, then it makes sense to skip the formal slope band analysis and to exercise the Guaranteed Maximum RFA option.

To do the slope band analysis, perform the following steps:

1. Obtain a topographical map
2. Determine the degree of slope for each slope band based on the zoning classification. Color each slope band with the corresponding color from the key.
3. Draw a rough section through the site and assign a “slope band” to segments of the site, depending on the severity of the slope.

4. Multiply the total area of each slope category by the Floor Area Ratio (FAR) given in Table 2 of the Baseline Hillside Ordinance. Use your property’s zoning to determine which FARs to use.   For R1 zoning:

5. The maximum RFA per the slope band analysis is 1017.15 SF.

Now a decision must be made. You are allowed two alternative routes to determine the maximum RFA for your site.

1. Slope Analysis + 20% Bonus

OR

2. Minimum Guaranteed RFA of 1000 SF + 30% Bonus

In our case, since we have already completed the slope band analysis and since both routes will give us similar maximum RFA numbers, we will stay with the slope band analysis and go for the 20% additional RFA bonus.

After a review of the 7 bonus options available to us, we will obtain a 20% additional RFA bonus for exercising one of the following:

1. Proportional Stories Option
2. Front Façade Setback Option
3. Green Building Option

 

 

 

 

 

 

 

 

 

 

 

 

The 7 different options for the bonuses range from the Proportional Stories Option (to encourage designs that stagger volumes rather than mass them) to the Green Building Option (must satisfy Tier 1 or higher of the LA Green Building Code).   Only one bonus per property can be used.  We will use the proportional stories option.

If we needed more square footage, we could have used the Minimum Guaranteed RFA of 1000 SF plus 30% bonus for a total of 1300 square feet. However the total of 1,220.58 square feet is sufficient for our program requirements.

4. Height Limits

809 Higgins St. is a Height District 1 (R1-1) but it is subject to the Height Limits of the Baseline Hillside Ordinance.

We want to maximize the usable square feet of this home, so we want to be able to use the roof as an exterior space.   Therefore we will keep the roof slope at less than 25%.   In doing so, Table 5 will require us to stay within a maximum height of 28 feet (y=28’).

That is great because it keeps us within the 28 feet height needed to maintain a 4 feet side yard setback. If we went above 28 feet, we would have to add another foot to the side yard setbacks, thus reducing our Buildable Zone to just 15 feet wide instead of the 17 feet that we now have.

Because 809 Higgins St. fronts a Substandard Hillside Limited Street and is subject to the 5-feet Front Yard Setback, there is an important provision to note (§12.21.C.10(d)(5)).

The provision limits any portion of a building within 20 feet of the front yard setback line to a height of 24 feet. This protects the traditional character of the streetscape by keeping the vertical lines of the homes lower and set back from the street.

The massing looks like an upper level front deck connected to an interior kitchen/living area would be great idea. That will add usable square feet without affecting the RFA numbers (see What is Residential Floor Area (RFA) in Section 2, page 8 of the Baseline Hillside Ordinance).

Per the envelope height restrictions, we need to trim a bit of our height.

Creating the stepped outline allows us to keep the building volume within the maximum envelope height while also accommodating for steps to access the roof.

5. Lot Coverage & Grading

At 809 Higgins Street, the lot is 2,500 SF.

Therefore by the base rules, total grading allowed is 500 + (2,500 * 5%) = 625 cubic yards.

However, for lots fronting a Substandard Hillside Limited Street, the quantity of earthwork import is limited to 375 cubic yards and the earthwork export is limited to 750 cubic yards.   But the total import/export quantity must remain below the base maximum allowed grading quantities.

At 809 Higgins Street, the maximum allowed is 625 cubic yards. We can export 625 cubic yards, or export just 250 cubic yards while importing 375 cubic yards.

Our design calls for about 321 CY of cut, 2 CY of fill, and 319 CY to export. This is well within the maximum allowable.

Estimated Earthwork Quantity
Estimated Cut	321 CY
Estimated Fill	2 CY
Export	319 CY

6. Retaining Wall

The LAMC provides guidelines for retaining wall construction in A or R zoned Hillside Areas. It limits retaining wall heights at 10’. That is not enough for our site.

But it also allows for two 10’ walls nearly stacked on top of one another, for a total height of 20’ provided that the top 10’ portion of the wall is stepped back the minimum of 3’ from the bottom 10’.

7. Final Solution