§ 27-658 Depth of foundations.
AC § 27-658
(a)Footings and Pile Caps. The bottom surface of any footing, pier, pile cap, or other foundation construction, other than grade beams, shall be carried down at least four feet below the lowest level of the adjoining ground or pavement surface that is exposed to frost, except as follows: (1) In refrigerator, cold storage, or similar areas, the depth shall be increased as required to found the construction below the potential level of freezing in the soil, or loss of heat from the soil shall be prevented by insulation, warm air ducts, circulating systems, or equivalent means.
(2)For foundation elements resting on rock, the footings may rest on the rock surface at shallower depths than those indicated above, provided that visual inspection of the rock surface directly underlying the bearing area shows it to be free of seams, cracks, or disintegrated materials that could serve as reservoirs for water and thus be subject to freezing.
(3)For foundation elements in the interior of closed and heated buildings, or in cases where the soil underlying the foundation is not subject to frost action, there shall be no mandatory minimum requirement for embedment.
(4)Mobile or portable buildings not more than one story high may be supported on foundation elements bearing at grade, subject to the following conditions: a. The building shall be supported on jacks, wedges, or other devices that will permit readjustment of level in the event of displacement. b. The bearing capacity of the underlying soil shall be adequate to support the building loads without rupture. Where the building is to be supported on nominally unsatisfactory bearing materials, the provisions of sections 27-677 and 27-679 of article four of this subchapter shall apply except that, where the bearing material is confined under pavement and the bearing pressure on the surface of the soil material does not exceed five hundred psf, special investigation of the foundation will not be required. c. The bearing area shall be well drained and not subject to inundation. d. The levels of the foundations shall be checked and adjusted to compensate for displacements at least once every year, and the owner shall maintain a record of such work, available for inspection by the commissioner.
(5)Where piles project above grade and displacement of the pile cap is prevented by interposing a space between the underside of the cap and the ground, the requirement for embedment of the cap below the level of frost penetration shall not apply.
(b)Grade beams. The bottom surface of any grade beam shall be carried down at least eighteen inches below the lowest level of the adjoining ground or pavement surface that is exposed to frost.
