Pile Foundations – General Requirements

NYC Admin. Code tit. 27, ch. 1, subch. 11, art. 7

in effect

NYC Admin. Code § 27-688 Administrative requirements.

§ 27-688 Administrative requirements. (a) Identification of piles. A plan showing clearly the designation of all piles by an identifying system shall be filed with the commissioner prior to installation of such piles. All detailed records for individual piles shall bear an identification corresponding to that shown on the plan. A copy of such plan shall be available at the site for inspection at all times. (b) Record of pile driving. A record of the penetration and behavior of each pile during installation shall be kept by the architect or engineer designated in section 27-721 of article thirteen of this subchapter. Such records shall be prepared on forms furnished by, or satisfactory to, the commissioner and, upon the completion of pile installation, shall be filed with the commissioner together with the records of any additional borings or subsurface information obtained during installation of the piles, and plans showing any deviations of the pile or related constructions (including any corrective measures) from the details and locations shown on the approved plans. Inspection of piling and pile load tests shall conform to the requirements of section 27-721 of article thirteen of this subchapter.

NYC Admin. Code § 27-689 Minimum pile penetrations.

§ 27-689 Minimum pile penetrations. (a) Required by soil bearing capacity. The provisions of paragraph one of subdivision (b) of section 27-700 of article eight of this subchapter shall apply. (b) Required for lateral restraint. The provisions of section 27-694 of this article shall apply. (c) Piles located near a lot line. Piles located near a lot line shall be designed on the assumption that the adjacent lot will be excavated to a depth of ten feet below the nearest legally established curb level. Where such excavation would reduce the embedded length of the pile, the portion of the pile exposed shall be considered as providing no lateral or vertical support, and the load-carrying determination in accordance with the provisions of article eight of this subchapter shall be made after the resistance offered by the soil that is subject to potential excavation has been discounted.

NYC Admin. Code § 27-690 Use of existing piles at demolished structures.

§ 27-690 Use of existing piles at demolished structures. Piles left in place where a structure has been demolished shall not be used for the support of new construction unless satisfactory evidence, including load or hammer testing of representative piles, can be produced indicating the capacity, length, and driving conditions of the piles. The load bearing value for such existing piles shall be the least of the values indicated by: (1) the load or hammer test, (2) the capacity of the pile as a structural member, and (3) the allowable bearing pressure on the soil underlying the pile tips, all in accordance with the provisions of article eight of this subchapter.

NYC Admin. Code § 27-691 Tolerance and modification of design due to field conditions.

§ 27-691 Tolerance and modification of design due to field conditions. (a) Tolerance in alignment of the pile axis. If the axis of any pile is installed out of plumb or deviates from the specified batter by more than four per cent of the pile length, the design of the foundation shall be modified as may be necessary to resist the resulting vertical and lateral forces. In types of piles for which subsurface inspection is not possible, this determination shall be made on the exposed section of the pile, which section, at the time of checking axial alignment, shall not be less than two feet. In piles which can be checked for axial alignment below the ground surface, the sweep of the pile axis shall not exceed four per cent of the embedded length. (b) Tolerance in location of the head of the pile. A tolerance of three inches from the designed location shall be permitted in the installation of each pile, without reduction in load capacity of the pile group. Where piles are installed out of position in excess of this amount, the true loading on such piles shall be analytically determined from a survey which defines the actual location of the piles as driven, and using the actual eccentricity in the pile group with respect to the line of action of the applied load. If the total load on any pile, so determined, is in excess of one hundred ten per cent of the allowable load bearing capacity, correction shall be made by installing additional piles or by other methods of load distribution, as required to reduce the maximum pile load to one hundred ten per cent of the capacity. (c) Bent piles. Where piles have been bent during installation, and the amount of the bend exceeds the allowable tolerance for alignment of the pile axis in subdivision (a) of this section, the condition shall be investigated and, where required, correction made by the installation of additional piles, by strengthening the bent piles, by reduction in capacity or other means acceptable to the commissioner.

NYC Admin. Code § 27-692 Minimum spacing of piles.

§ 27-692 Minimum spacing of piles. Piles shall be spaced to meet the following requirements: (1) Spacing of piles shall provide for adequate distribution of the load on the pile group to the supporting soil, in accordance with the provisions of subdivision (b) of section 27-700 of article eight of this subchapter. (2) In no case shall the minimum center-to-center spacing of piles be less than twenty-four inches, nor less than the values for specific types of piling as indicated in article ten of this subchapter. Unless special measures are taken to assure that piles will penetrate sufficiently to meet the requirements of section 27-689 of this article without interfering with or intersecting each other, the minimum center-to-center spacing of piles shall be twice the average diameter of the butt for round piles; one and three-quarters times the diagonal for rectangular piles; or, for taper piles, twice the diameter at a level two-thirds of the pile length measured up from the tip. In cases of practical difficulty, the spacing of new piles from existing piles under an adjacent building may be less than the above values provided that the requirements relating to minimum embedment and pile interference are satisfied and that the soil under the proposed and existing buildings is not overloaded by the closer pile grouping.

NYC Admin. Code § 27-693 Minimum section.

§ 27-693 Minimum section. Except as provided in article ten of this subchapter for timber piles, no tapered pile shall be less than six inches in diameter at any section, nor have less than an eight inch diameter at cutoff. The taper of any tapered section may be uniform or may occur in steps. No pile of uniform section shall have a diameter of less than eight inches, or, if not circular, a dimension of less than seven and one-half inches. Tapered shoes or points of lesser dimensions may be attached to the tips of piles.

NYC Admin. Code § 27-694 Capping and bracing of piles.

§ 27-694 Capping and bracing of piles. (a) Capping of piles. (1) EMBEDMENT. Tops of all piles shall be embedded at least three inches in concrete caps. Such concrete shall conform to the provisions of article five of subchapter ten of this chapter and shall extend at least four inches beyond the edge of all piles. Alternatively, and only where the piles project above the future grade and will be readily accessible for visual inspection at all times, the tops of the piles may be capped with timber or steel caps, which shall be connected to the piles. Cap plates will not be required for steel H piles embedded in a reinforced concrete cap. Inspection of pile caps shall be as required in section 27-722 of article thirteen of this subchapter. (2) UPLIFT. Where piles are subject to uplift, they shall be anchored into the cap to resist at least one and one-half times the amount of such uplift without exceeding the basic allowable stresses as established in subchapter ten. (3) REINFORCEMENT. Reinforcement shall be placed to provide at least three inches of clear cover, measured to the surface of the pile cap that is in contact with the ground. All reinforcement adjacent to timber or concrete piling shall have a minimum of one inch of concrete protection. Reinforcement shall extend to within four inches of the edges of the pile cap. (4) DESIGN. Except as modified above, concrete pile caps shall be designed in accordance with the provisions of reference standard RS 10-3. (b) Bracing of piles. Except for short piles as described in subdivision (c) of this section, every pile shall be laterally braced to conform with one or more of the following provisions: (1) RIGID CAP. Three or more piles connected by a rigid cap shall be considered as being braced provided that the piles are located in radial directions from the centroid of the group not less than sixty degrees apart (within a tolerance of three inches in location of the pile.) A two-pile group, in a rigid cap, shall be considered to be braced along the axis connecting the two piles. (2) BRACE BEAMS. Piles may be braced by the use of brace beams or ties rigidly connecting to at least two other piles in radial directions not less than sixty degrees nor more than one hundred twenty degrees apart. Concrete brace beams shall have minimum dimensions of one-twentieth of the clear distance between pile caps, but not less than eight inches. All brace beams shall be proportioned to resist a minimum axial load equal to three per cent of the total axial load capacity of the piles that are to be braced by that beam, plus the moment due to any eccentricity between the centroid of the pile group and the line of action of the applied load. Where underlain by soil of class 9-65, 10-65 or 11-65, brace beams shall be proportioned to support the weight of soil, slab-on-ground, and live load on the slab-on-ground that is contained within vertical planes projected upward from the lateral limits of the brace beam. The design of brace beams to resist these loads shall conform to the provision of subchapter ten of this chapter. (3) CONCRETE SLAB-ON-GRADE. A continuous concrete slab or mat on grade, that is five inches or more in thickness and reinforced, and that extends at least forty feet in each direction and is anchored to the pile caps (or in which the piles are embedded at least three inches), may be used in lieu of brace beams for bracing of pile caps, providing that the slab is supported on material having an allowable bearing pressure of one and one-half tons per square foot or better and such material is not underlain by nominally unsatisfactory bearing materials. (4) OTHER MEANS. Piles may be braced by anchors, anchor wall, or other means acceptable to the commissioner. (5) FLOOR SYSTEM. Single-pile or two-pile groups or a single line of piles may be considered to be adequately braced if connected to, and braced by, a self supporting floor system provided: (1) that the details and dimensions of the floor and the wall or pier are of adequate strength to resist lateral displacement of the pile cap under conditions of maximum eccentricity of the applied load; and (2) that the wall or pier is braced until connection of the floor framing is made and the flooring (or slab) is in place. (6) SPECIAL REQUIREMENTS FOR BRACING BATTER PILES. The provisions of paragraphs one through five of this subdivision above shall apply. In addition, provisions shall be made to oppose the lateral thrust resulting from the pile inclination. (c) Bracing of short piles. (1) All pile caps supported by piles that penetrate less than ten feet below cutoff level or less than ten feet below ground level shall be braced against lateral movement. Such bracing may consist of connection to other pile caps that encompass piles embedded more than ten feet below those levels; the use of suitable anchors, connection to a slab-on-grade or the floor system as described in paragraphs three and five of subdivision (b) of this section, or by other equivalent means. The heads of the piles shall be fixed in the cap. In no event shall more than fifty percent of the piles in the foundation of any building penetrate less than ten feet below cut-off-level or less than ten feet below ground level. (2) Where the embedded length of piles located near a lot line would be reduced to less than ten feet by excavation of the adjacent site to a depth of ten feet below the nearest established curb level, the provisions of paragraph one of this subdivision shall apply.

NYC Admin. Code § 27-695 Splicing of piles.

§ 27-695 Splicing of piles. Splices shall be constructed so as to provide and maintain true alignment and position of the component parts of the pile during installation and subsequent thereto, and shall be of adequate strength to transmit the vertical and lateral loads (including tensions) and the moments occurring in the pile section at the location of the splice without exceeding the allowable stresses for such materials as established in subdivision (a) of section 27-700 of article eight of this subchapter. Except for piles which can be visually inspected after driving, splices shall develop at least fifty per cent of the capacity of the pile in bending. In addition, all pile splices in the upper ten feet of the pile section shall be capable of resisting (at allowable working stresses) the moment and shear that would result from an assumed eccentricity of the pile load of three inches, or the pile shall be braced in accordance with the provisions of section 27-694 of article seven of this subchapter to other piles that do not have splices in the upper ten feet of embedment. For piles located near a lot line, the embedded length of such piles shall be determined on the basis that the adjacent site will be excavated to a depth of ten feet below the nearest established curb level.

NYC Admin. Code § 27-696 General requirements for installation of piles.

§ 27-696 General requirements for installation of piles. (a) Protection of adjacent property. Piles shall be installed with adequate provision for the protection of adjacent buildings and property. (b) Protection of the pile during installation. Piling shall be handled and installed to the required penetration and resistance by methods that leave their strength unimpaired and that develop and retain the required load-bearing resistance. Any damaged pile shall be satisfactorily repaired or the pile shall be rejected. Subject to the approval of the commissioner, damaged piles may be used at a fraction of the design load as determined by the architect or engineer in lieu of repair or rejection. (c) Protection of pile materials after installation. Where boring records or site conditions indicate possible deleterious action on pile materials due to soil constituents, changing water levels, or other causes, such materials shall be adequately protected by preservatives or encasements that will not be rendered ineffective by driving and that will prevent such deleterious action. The following specific provisions shall apply: (1) Untreated timber piles shall not be used unless the top level of the pile is below the permanent water table. The permanent water table level shall not be assumed higher than the invert level of any sewer, drain, or subsurface structure in the adjacent streets, nor higher than the water level at the site resulting from the lowest drawdown of wells or sumps, but in no case shall untreated timber piles be used where the cut-off level is less than ten feet below the adjacent legal grade. Where treated piles are required, preservative treatment shall consist of impregnation with creosote or a creosote solution or, for piles entirely embedded below grade, a pentachlorophenal solution may be used. Treatment shall be in accordance with all requirements of reference standard RS 11-6. (2) Piles installed in ash or garbage fills, cinder fills, or which are free-standing in or near a seawater environment, or which are used for the support of chemical plants, coal piles or under similar conditions of chemical seepage or aggressive action, or which are used for support of electrical generating plants, shall be investigated regarding the need for special protective treatment and, where protective treatment is indicated, shall be protected against deterioration by encasement, coating, or other device acceptable to the commissioner. (d) Equipment. Equipment and methods for installing piles shall be such that piles are installed in their proper position and alignment, without damage. Equipment shall be maintained in good repair.

NYC Admin. Code § 27-697 Use of uncased concrete pile shafts.

§ 27-697 Use of uncased concrete pile shafts. The use of uncased shafts (i.e., where the concrete of the pile shaft is in direct contact with the surrounding soil) will be permitted under the following conditions: (a) For bored piles. Where the bored hole is maintained free of water before and during placement of the concrete and the sides and bottom can be inspected prior to such placement, and provided that no displacement pile shall be installed within fifteen feet of any bored pile. (b) For driven piles (including all piles wherein installation utilizes a temporary casing). The maximum length of the uncased shaft shall be limited to ten feet unless otherwise permitted by the commissioner. Uncased shafts will be permitted to be formed in soil below the water table but shall not be formed in any soil of class 9-65 that is of medium or soft consistency; in any soil of class 10-65 that is of medium or loose density; or in any soil of class 11-65.

NYC Admin. Code § 27-698 Where more than one pile type, pile capacity, or method of pile installation is used.

§ 27-698 Where more than one pile type, pile capacity, or method of pile installation is used. Wherever it is proposed to: (1) construct a foundation for a building utilizing piles of more than one type or capacity; (2) modify an existing foundation by the addition of piles of a type or capacity other than those of the existing piling; (3) construct or modify a foundation utilizing different methods or more than one method of installation, or using different types or capacities of equipment (such as different types of hammers having markedly different striking energies or speeds); or (4) support part of a building on piles and part on footings, the several parts of the building supported on the different types, capacities, or modes of piling shall be separated by suitable joints providing for differential movement, or a report shall be submitted by the architect or engineer establishing to the satisfaction of the commissioner that the proposed construction is adequate and safe, and showing that the probable settlements and differential settlements to be expected will not result in instability of the building or stresses in the structure in excess of the allowable values established in subchapter ten of this chapter. The provisions of subdivision (d) of section 27-700 of article eight of this subchapter relating to required load tests shall apply separately and distinctly to each different type or capacity of piling, method of installation, or type or capacity of equipment used, except where analysis of the probable, comparative behavior of the different types or capacities of the piles or the methods of installation indicates that data on one type or capacity of pile permits a reliable extrapolation of the probable behavior of the piles of other types and capacities.

NYC Admin. Code § 27-699 Pile materials.

§ 27-699 Pile materials. The provisions of sections 27-580 and 27-588 of article one of subchapter ten of this chapter relating to "classification of materials, assemblies and methods of construction" and to the use of "used and unidentified materials" shall apply.

Source: City of New York, Charter, Administrative Code and Rules (American Legal Publishing XML export, codelibrary.amlegal.com)URL: https://codelibrary.amlegal.com/codes/newyorkcity/latest/NYCadmin/0-0-0-51462Fetched: 10/24/2026