CHAPTER 18 FOUNDATIONS AND RETAINING …

1 CHAPTER 18 FOUNDATIONS AND RETAINING WALLSSECTION Scope. Provisions of this CHAPTER shall govern thedesign, construction, and resistance to water intrusion offoundations for buildings and : Buildings and structures located within theHigh Velocity Hurricane Zone shall comply with the pro-visions of Sections 1816 through 1802 DEFINITIONSFor definitions, see CHAPTER When excavating for buildings or excavationsaccessory thereto, such excavations shall be made safe toprevent any danger to life and property, and shall be inaccordance with Florida Statutes Section TrenchSafety Permanent excavations shall have RETAINING wallsof sufficient strength made of steel, masonry, or reinforcedconcrete to retain embankments, together with any sur-charged Excavations for any purpose shall not extendwithin 1 ft (305 mm)

2 Of the angle of repose or naturalslope of the soil under any footing or foundation, unlesssuch footing or foundation is first properly underpinned orprotected against Support of adjoining buildings and Notice to adjoining structures. Notice to theowner of adjoining buildings or structures shall be servedin writing by the one causing the excavation to be made atleast ten days before an excavation is commenced. Thenotice shall state the depth and location of the Excavation 10 ft (3048 mm) or less. When anexcavation extends not more than 10 ft (3048 mm) belowthe established curb grade nearest the point of excavationunder consideration, the owner of the adjoining structureor building shall be afforded the necessary license to enterthe premises where the excavation is to be made, and at hisown expense, shall provide the necessary underpinning Excavation greater than 10 ft (3048 mm) When an excavation extends more than 10 ft(3048 mm)

3 Below the established curb grade nearestthe point of excavation under consideration, the onecausing the excavation to be made, if given the neces-sary license to enter the adjoining premises, shall pro-vide at his own expense one of the following:1. Underpinning and protection required by thatpart of the excavation which extends to a depthgreater than 10 ft (3048 mm) below the estab-lished curb grade nearest the point of excavationunder consideration, whether or not the existingfootings or FOUNDATIONS extend to the depth of 10ft (3048 mm) or more below curb grade, or2. Shoring and bracing of the sides of the excava-tion required to prevent any soil movement intothe excavation.

4 If permanent lateral support isprovided, the method used must satisfy require-ments of the building If the necessary license is not afforded theperson causing the excavation to be made, it shall bethe duty of the owner failing to afford such license toprovide the required underpinning or protection forwhich purpose he shall be afforded the necessarylicense to enter the premises where such excavation isto be Unestablished curb grade. If there is not an estab-lished curb grade, the depth of excavation shall be referred tothe level of the ground at the point under Difference in adjacent curb If an existing building or structure requiringunderpinning or protection is so located that its curbgrade or level is at a higher level than the level to whichthe excavation is properly referred.

5 Then such part ofthe required underpinning or protection that is neces-sary because of the difference in these levels shall bemade and maintained at the joint expense of the ownerof the building or structure and the person causing theexcavation to be For the purpose of determining such part ofthe underpinning or protection that is necessarybecause of such difference in levels, the level to whicha building more than 5 ft (1524 mm) back of the streetline is properly referred shall be considered to be thelevel of the natural ground surface adjoining the build-ing or Party walls . A party wall, which is in good con-dition and otherwise suitable for continued use, shall beunderpinned or protected as required at the expense of theperson causing the excavation to be BUILDING CODE Adjoining structure protection.

6 Where the nec-essary license has been given to the person making anexcavation to enter any adjoining structure for the purposeof underpinning or protecting it, the person receiving suchlicense shall provide for such adjoining structure adequateprotection against injury from the elements resulting fromsuch Backfill. Only approved granular materials shallbe used for backfill. It shall be properly compacted in orderto prevent lateral displacements of the soil of the adjoiningproperty after the removal of the shores or 1804 FOOTINGS AND FOUNDATIONS shall be built on undisturbed soil orproperly compacted fill material. FOUNDATIONS shall beconstructed of materials described in this Pile FOUNDATIONS shall be designed and con-structed in accordance with The bottom of FOUNDATIONS shall extend no lessthan 12 inches (305 mm) below finish Temporary buildings and buildings not exceed-ing one story in height and 400 sq ft (37 m2)

7 In area shallbe exempt from these Excavations for FOUNDATIONS shall be backfilledwith soil which is free of organic material, constructiondebris and large Where water impacts the ground from a roof val-ley, downspout, scupper or other rain water collection ordiversion device, provisions shall be made to prevent soilerosion and direct the water away from the Finish grade shall be sloped away from the foun-dation for The area under footings, FOUNDATIONS and con-crete slabs on grade shall have all vegetation, stumps,roots and foreign materials removed prior to their con-struction. Fill material shall be free of vegetation and for-eign Soils Plain concrete, masonry or timber shall be so designed that the allowable bearingcapacity of the soil is not exceeded.

8 If structural plain con-crete, masonry or timber footings are used, they shall reston undisturbed or compacted soil of uniform density andthickness. Compacted soils shall be tested to a minimumof 95% of Modified Proctor in accordance with ASTM D1557 and compacted and tested in lifts not to exceed 12inches (305 mm). If sufficient compactibilities exist, soilsmay be compacted and tested in greater lift Questionable soil. Where the bearing capacityof the soil is not definitely known or is in question, thebuilding official may require load tests or other adequateproof as to the permissible safe bearing capacity at thatparticular location. To determine the safe bearing capacityof soil, it shall be tested at such locations and levels asconditions warrant, by loading an area not less than 4 sq ft( m2) to not less than twice the maximum bearingcapacity desired for use.

9 Such double load shall be sus-tained by the soil for a period of not less than 48 hourswith no additional settlement taking place, in order thatsuch desired bearing capacity may be used. Subsoil con-ditions shall be examined at the expense of the owner,when deemed necessary by the building Natural solid ground or piles. Foundationsshall be built upon natural solid ground. Where solid nat-ural ground does not occur at the foundation depth, suchfoundations shall be extended down to natural solidground or piles shall be used. FOUNDATIONS may be builtupon mechanically compacted earth or fill material sub-ject to approval by the building official upon submittal ofevidence that the proposed load will be adequately Differential settlement.

10 Where footings aresupported by soils of widely different bearing capacity, theallowable bearing values of the more yielding soil shall bereduced or special provisions shall be made in the designto prevent serious differential Shifting or moving soils. When it is definitelyknown the top or subsoils are of a shifting or moving char-acter, all footings shall be carried to a sufficient depth toinsure stability. The excavation around piers shall be back-filled with soils or materials which are not subject to suchexpansion or Groundwater table investigation. A subsurfacesoil investigation shall be performed to determine the pos-sibility of the groundwater table rising above the proposedelevation of the lowest floor when such floor is locatedbelow the finished ground level adjacent to the foundationfor more than 75% of the perimeter of the : A subsurface soil investigation shall not berequired when either of the following conditions is sat-isfied:1.