1805.4.2 Foundation drain.

A foundation drain shall be installed where required by the registered design professional. The foundation drain, including layout, materials, and cleanouts, shall be designed by the registered design professional.

1805.4.3 Drainage discharge.

The drainage course and foundation drain shall discharge by gravity or mechanical means into an approved drainage system that complies with the New York City Plumbing Code and any other laws or requirements of agencies having jurisdiction.

1805.5 In situ walls.

In situ walls (such as slurry walls, tangent pile walls, and secant pile walls) with joints sealed by grouting or other methods acceptable to the engineer shall not require waterproofing or dampproofing unless required by the engineer.

Section BC 1806: Allowable Load-bearing Values of Soils and Rock

1806.1 Design.

The allowable bearing pressures provided in Table 1806.1 shall be used with the allowable stress design load combinations specified in Section 1605.3.

Table 1806.1
Allowable Bearing Pressures

Class of Materials (Notes 1 and 3)	Maximum Allowable Bearing Pressure (TSF)	Maximum Allowable Bearing Pressure (kPa)
1.   Bedrock (Notes 2 and 7)
1.a   Hard sound rock	60	5,746
1.b   Medium rock	40	3,830
1.c   Intermediate rock	20	1,915
1.d   Soft rock	8	766
2.   Sandy gravel and gravel (GW, GP) (Notes 4, 8, and 9)
2.a   Dense	10	958
2.b   Medium	6	575
3.   Granular soils (GC, GM, SW, SP,SM, and SC) (Notes 4, 5, 8, and 9)
3.a   Dense	6	575
3.b   Medium	3	287
4.   Clays (SC, CL, and CH) (Notes 4, 6, 8,and 9)
4.a   Hard	5	479
4.b   Stiff	3	287
4.c   Medium	2	192
5.   Silts and silty soils (ML and MH) (Notes 4, 8, and 9)
5.a   Dense	3	287
5.b   Medium	1.5	144
6.   Nominally Unsatisfactory Bearing Materials:    Loose granular soils    Soft clay soils    Loose Silt    All organic silts, organic clays, peats, soft clays, granular soils and varved silts	See 1806.2.1	See 1806.2.1
7.   Controlled and uncontrolled fills.	See 1806.2.2 or 1806.2.3	See 1806.2.2 or 1806.2.3

 

Notes:

1.   Where there is doubt as to the applicable classification of a soil or rock stratum, the allowable bearing pressure applicable to the lower class of material to which the given stratum might conform shall apply.

2.   The tabulated values of allowable bearing pressures apply only for massive rocks, or for sedimentary or foliated rocks where the strata are level or nearly so, and then only if the area has ample lateral support. The allowable bearing pressure for tilted strata and their relation to nearby slopes or excavations shall be evaluated by the engineer responsible for the geotechnical investigation. The tabulated values for Class 1a materials (hard sound rock) may be increased by 25 percent provided the engineer performs additional tests and/or analyses substantiating the increase.

3.   For intermediate conditions, values of allowable bearing pressure shall be estimated by interpolation between indicated extremes.

4.   Footing embedment in soils shall be in accordance with Section 1809.3 and the width of the loaded area shall not be less than 18 inches (457.2 mm), unless analysis demonstrates that the proposed construction will have a minimum factor of safety of 2.0 against shear failure of the soil.

5.   Estimates of settlements shall govern the allowable bearing pressure, subject to the maximums given in this table, and as provided in Section 1806.2.

6.   Allowable bearing pressure of clay soils shall be established on the basis of the strength of such soils as determined by field or laboratory tests and shall provide a factor of safety against failure of the soil of not less than 2.0 computed on the basis of a recognized procedure of soils analysis, shall account for probable settlements of the building and shall not exceed the tabulated maximum values.

7.   Allowable bearing pressure may be increased due to embedment of the foundation. The allowable bearing pressure for intermediate rock (1c), medium hard rock (1b), and hard sound rock (1a) shall apply where the loaded area is on the rock surface. Where the loaded area is below the rock surface and is fully confined by the adjacent rock mass and provided that the adjacent rock mass above the bearing surface is of rock class 1c or better, and the rock mass has not been shattered by blasting or otherwise is or has been rendered unsound, the allowable bearing pressure may be increased 10 percent of the base value for each 1 foot (0.3 meters) of embedment below the surface of the adjacent rock surface in excess of 1 foot (0.3 meters), but shall not exceed 200 percent of the values.

8.   The allowable bearing pressure for soils of Classes 2, 3, 4, and 5 determined in accordance with Notes 3, 4, and 5 above, shall apply where the loaded area is embedded 4 feet (1220 mm) or less in the bearing stratum. Where the loaded area is embedded more than 4 feet (1220 mm) below the adjacent surface of the bearing stratum, and is fully confined by the weight of the adjacent soil, the allowable bearing pressure may be increased 5 percent of the base value for each 1-foot (304.8 mm) additional embedment, but shall not exceed twice the values. Increases in allowable bearing pressure due to embedment shall not apply to soft rock, clays, silts and soils of Classes 6 and 7.

9.   The allowable bearing pressure for soils of Classes 2, 3, 4, and 5 determined in accordance with this table and the notes thereto, may be increased up to 1/3 where the density of the bearing stratum below the bottom of the footings increases with depth and is not underlain by materials of a lower allowable bearing pressure. Such allowable bearing pressure shall be demonstrated by a recognized means of analysis that the probable settlement of the foundation due to compression, and/or consolidation does not exceed acceptable limits for the proposed building.

10.   The maximum toe pressure for eccentrically loaded footings may exceed the allowable bearing pressure by up to 25 percent if it is demonstrated that the heel of the footing is not subjected to tension.

1806.2 Allowable bearing pressure.

The allowable bearing pressure for supporting soil and rock shall not exceed the values specified in Table 1806.1, unless data to substantiate the use of a higher value are developed and contained in the engineer's geotechnical report, and the commissioner approves such value. Allowable bearing pressure shall be considered to be the pressure at the base of a foundation in excess of the effective stress existing at the same level prior to construction operations.