COUNTY OF LOS ANGELES Hillside Structures DEPARTMENT OF

COUNTY OF LOS ANGELES
DEPARTMENT OF PUBLIC WORKS BUILDING AND SAFETY DIVISION

Hillside Structures
PLAN REVIEW LIST

GENERAL PROJECT INFORMATION

PLAN CHECK NO. JOB ADDRESS

DISTRICT NO

CITY

ZIP

NOTE: Numbers in the parenthesis ( ) refer to sections of the 2008 edition of the Los Angeles County Building Code, Table (T).
INSTRUCTIONS
• Corrections with circled item numbers apply to this plan check.
• In the left-hand margin of the circled corrections, please indicate the sheet number and detail or note number on the plans where the corrections are made. Resubmit marked original plans and two corrected sets of plans, calculations and this plan review list.
• Incomplete, unclear, or faded drawings or calculations will not be accepted.
• Incorporate all comments as marked on checked set of plans and calculations and these correction sheets.

GENERAL REQUIREMENTS

GENERAL

1. This ( ) new building or ( ) addition to an existing building shall be designed to comply with the provisions of Section 1613.7, Seismic Design Provisions for Hillside Buildings, as it is constructed on or into slopes steeper than 1 unit vertical in 3 units horizontal (33.3% slope). Furthermore, it also applies to the entire building even if only a portion of the building is supported on or into the slope. (1613.7.1)

2. Both the addition to the existing building, and the existing building shall comply with the provisions of Section 1613.7.

3. Identify the Base Level Diaphragm on structural

framing plans. (Base Level Diaphragm is defined as

the floor at, or closest to, the top of the highest level of

the foundation including the highest floor level

connected to the stems of the retaining/basement

walls).

(1613.7.3)

4. The base shear, including forces from the base level diaphragm, shall be resisted by direct connections from a diaphragm strut or collector provided in the base level framing to the foundation. Where the floor below the base extends to the uphill foundation, the connection shall be made directly to the foundation. (1613.7.5.1)

5. Maximum spacing between primary anchors/collectors

is 30 ft.

(1613.7.5.2)

6. Where an interior vertical lateral resisting element (e.g. interior shear walls) occurs above and in contact with the base level diaphragm, a diaphragm strut and primary anchor directly below the element shall be provided and connected to the uphill foundation. (1613.7.5.2)

7. Provide details for primary and secondary anchors and

diaphragm strut design.

(1613.7.8)

a. Wood diaphragm strut collector and wood members connected to the primary anchor shall be min. 3 x members.

b. Provide minimum 3/16-in. x 2-in. square washer and 1/4-in. x 2.5-in. square washer at 1/2-in. and 5/8-in. diameter bolts, respectively, when they are used to connect anchors to wood members.

c. The diaphragm to foundation anchorage shall NOT be accomplished by the use of toe-nailing, nails subject to withdrawal, or wood in cross-grain bending or cross-grain tension.

8. Grade beams shall extend at least 12-in. below the lowest adjacent grade and provide a minimum 24-in. distance horizontally from the bottom outside face of the grade beam to the face of the descending slope. (1613.7.10.1)

9. Where a footing or grade beam extends across a

descending slope, the stem wall, grade beam, or

footing shall extend up to a minimum 18-in. above the

highest adjacent grade. (EXCEPTION: At paved

garage and doorway entrances to the building, the

stem wall need only extend to the finished concrete

slab, provided the wood framing is protected with a

moisture proof barrier.)

(1613.7.10.2)

10. No ledgers are permitted when supporting a vertical

load of more than 100 pounds per lineal foot and

located within 48-in. of adjacent grade. Galvanized

steel ledgers and anchor bolts, with or without wood

nailers, or treated or decay resistant sill plates

supported on a concrete or masonry seat may be

used.

(1613.7.10.2)

11. All wood framed walls, including nonbearing walls,

when resting on a footing, foundation, or grade beam

stem wall, shall be supported on wood sill plates

bearing on a level surface.

(1613.7.10.3)

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12. The base of isolated wood posts (not framed into a

stud wall) supporting a vertical load of 4,000-lb. or

more and the base plate for a steel column shall

comply with the following:

(1613.7.10.4)

a. When the post or column is supported on a pedestal extending above the top of a footing or grade beam, the pedestal shall be designed and reinforced as required for concrete or masonry columns. The pedestal shall be reinforced with a minimum of four No. 4 bars extending to the bottom of the footing or grade beam.
b. The base plate anchor bolts or the embedded portion of the post base, and the vertical reinforcing bars for the pedestal, shall be confined with two No. 4 or three No. 3 ties within the top 5-in. of the concrete or masonry pedestal.
c. The base plate anchor bolts shall be embedded a minimum of 20 bolt diameters into the concrete or masonry pedestal. The base plate anchor bolts and bases shall be galvanized and each anchor bolt shall have at least two galvanized nuts above the base plate.

13. All steel beams to column supports shall be positively braced in each direction. Steel beams shall have stiffener plates installed on each side of the beam web at the column. The stiffener plates shall be welded to each beam flange and the bean web. Each braced connection or structural member shall consist of at least two 5/8-in. diameter machine bolds. (1613.7.10.5)

14. Top and bottom of footings and grade beams shall be

level, or stepped when the ground slope exceeds one

vertical in ten horizontal.

(1805.1)

CALCULATIONS

Downhill Directions

15. In developing the base shear for seismic design, the response modification coefficient (R) shall not exceed 4.5 for bearing wall and building frame system. (1613.7.4.2.2)

16. Each diaphragm below the base level diaphragm shall

be designed for all tributary loads at that level using a

minimum seismic force factor not less than the base

shear coefficient.

(1613.7.7.2)

17. Provide calculations for primary anchors (at and below the base level) per Sec. 1613.7.5.

a. Primary anchor and diaphragm strut shall be provided at each foundation extending downhill, underneath interior lateral force resisting elements above and in contact with the base level diaphragm.
b. The load path and diaphragm struts shall be fully developed into the diaphragm and into the foundation. The foundation must be shown to be adequate to resist the concentrated loads from the primary anchors.

18. Provide secondary anchors in the uphill foundation

connecting to diaphragm struts in the base level

diaphragm.

(1613.7.8)

19. Maximum spacing of secondary anchors at the Base Level Diaphragms shall be uniformly distributed along the uphill diaphragm edge, spaced at maximum 4-ft. on center, and designed for a minimum force equal to the base shear coefficient times the accumulated dead load of the building tributary to that level and not less than 600 pounds per lineal foot. (The foundation need not be designed to resist these additional forces.) (1613.7.6.2)

20. Below base level, provide secondary anchors at each floor diaphragms to the uphill foundation. Such anchors shall be uniformly distributed along the uphill diaphragm edge, spaced at maximum 4-ft. on center, and designed for a minimum force equal to the base shear coefficient times the accumulated dead load of the building tributary to that level and not less than 300 pounds per lineal foot. (The foundation need not be designed to resist these additional forces.) (1613.7.7.4)

21. Primary and secondary anchors and diaphragm struts

shall be designed as follows:

(1613.7.8)

a. Design for 125% of the tributary force.
b. The 1/3 allowable stress increase permitted under Sec. 1605.3.2 shall not be used when working (allowable) stress design method is used.
c. Use seismic load factor 1.7 for steel and concrete anchorage when the strength design method is used.
d. Wood ledgers shall not be used to resist crossgrain bending or cross-grain tension.
e. Primary Anchors, splices, and connections shall be designed in accordance with provisions of section 1613.7.8.

22. Wood structural panel wall sheathing, cement plaster

and lath, gypsum wallboard, and tension-only braced

frames shall not be used to resist lateral forces below

base. Level.

(1613.7.5.4)

23. Braced frames may be used to transfer forces from the

primary anchors and diaphragm struts to the

foundation provided the lateral forces do not induce

flexural stresses in any member of the frame or in the

diaphragm struts. Deflections of frames shall account

for the variation in slope of diagonal members when

the frame is not a rectangular shape.

(1613.7.5.4)

Normal to the Downhill Direction

24. Story drift below the base level diaphragm normal to

the downhill direction shall not exceed .005 times the

story height. The total drift from the base level

diaphragm to the top of the foundation shall not

exceed 3/4-in. (Where the story height varies because

of a stepped footing or story offset, the story height

shall be an average height). The calculated story drift

shall not be reduced by the effect of horizontal

diaphragm stiffness.

(1613.7.9.4)

25. For wind level forces design, the story drift limit is .0025 or one-half of the story drift limit due to seismic design.

26. In developing base shear; the response modification

coefficient (R) used shall not exceed 4.5 for bearing

wall and building frame systems.

(1613.7.9.2)

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27. The design lateral force shall be distributed to each resisting elements of varying heights in accordance with the stiffness of each individual element. (1613.7.9.5.1)

28. The stiffness of a stepped plywood shear wall may be

determined by dividing the wall into adjacent

rectangular elements, subject to the same top of wall

deflection. Sheathing and fastening requirements for

the stiffest portion shall be used for the entire wall.

Each section shall be anchored for shear and uplift at

each step. The minimum horizontal length of a step

shall be 8-ft. and the maximum vertical height of a step

shall be 2-ft. 8-in.

(1613.7.9.5.2)

29. Cement plaster and lath, gypsum wallboard, and tension-only braced frames shall not be used to resist lateral forces below the base level diaphragm. (1613.7.9.6)

ADDITIONAL COMMENTS

NOTES ON PLANS
The following notes must be included on the plans.
1. Nuts of the primary and secondary anchors fasteners shall be wrench tightened prior to inspection and covering.
2. Power-driven fasteners shall not be used to anchor sill plates except at interior nonbearing walls not designed as shear walls.
3. Exterior anchor bolts and post bases shall be galvanized and each anchor bolts shall have at least two galvanized nuts above the base plate.
4. The top of exterior pedestals must be sloped for positive drainage.
5. All main footing and grade beam reinforcement steel shall be bent into the intersecting footing and fully developed around each comer and intersection.
6. Periodic inspection by a Los Angeles County licensed deputy inspector is required for all structural connections, footings, grade beams, and retaining walls during installation.
7. Structural Observation by the Engineer or Architect of Record is required in accordance with section 1709.

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