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HomeMy WebLinkAbout04012010 BSC Agenda Item 5 STAFF REPORT Business of the Building and Standards Commission City, of West University Place, Texas AGENDA OF: April 1, 2010 DOCKET NO.: 10-03 DATE SUBMITTED: March 24, 2010 DEPARTMENT OF ORGIN: Development Services PREPARED BY: John R. Brown, MCP, CFM Chief Building Official PRESENTER: John R. Brown SUBJECT: Approval of the increased Errors and Omissions insurance and general STAFF PRESENTER: ordinance clean up regarding current code John R. Brown, MCP, CFM section number reference and deleting Chief Building Official verbiage requiring different enforcement after 2006. ATTACHMENTS: Code section C-104 STAFF SUMMARY Background: In January 2010 the BSC Board approved an increase in the amount of Errors and Omissions insurance from $250,000.00 per claim to $500,000.00 and $500,000.00 per year aggregate to $1,000,000.00 for Engineers. This is just to verify this was you intent and if approved it will be forwarded to City Council for approval. The general clean up shows if there was a change will have a st-Fik-edffeugh-with an underlined change beside it and if a removal only it will have a sk4kethfeugk only. I would like to present these minor changes as well for City Council approval along with the E & O insurance increase. 1 Appendix C, Technical Codes Sec. C-104. International Building Code. 1. The administrative officer is the building official. All hearings, variances etc. are handled by the BSC. 2. On sites primarily used for residential purposes, all roofs must have Class A or better fire residence, as determined under Section 1505. 1, except that wooden roofing materials are forbidden. 3. The foundation for each new building (and each new addition to a building) must meet all the criteria in this section, as applicable. Exception: If the building or addition does not contain habitable space (as defined in the IBC), it must meet only the requirements for "nonhabitable space," as indicated below. In this section: "AMA Lab" means a laboratory accredited by the American Association for Laboratory Accreditation on the basis of ISO/IEC 17025:1999 ("general requirements for the competence of testing and calibration laboratories"). "RLPE" means a licensed or registered professional engineer of the State of Texas who is: (1) Listed with the State Board of Professional Engineers in b"." (but, f em and f May ' 1, 2006, listing the structural branch is required)-; (2) Employed by a registered engineering firm of the State of Texas; and (3) (Unless waived by the BSC as provided in "f" below) covered by professional errors and omissions insurance that: (i) has limits of at least $250,000.00 $500,000.00 per claim (and at least $500;090:00 $1,000,000.00 per year, aggregate) and (ii) has effective dates-including any retroactive coverage date- that include the entire period when the person provides services or takes actions regulated by this section. "RLGE" means a person who is: (1) Either: (a) a registered professional geoscientist of the State of Texas, or (b) a licensed or registered professional engineer who is listed with the State Board of Professional Engineers in a relevant branch of engineering (civil, structural or geological) and employed by a registered engineering firm of the State of Texas; and (2) Covered by professional errors and omissions insurance that. (i) has limits of at least $250,000.00 $500,000.00 per claim (and at least $500,000.00 $1,000,000.00 per year, aggregate) and (ii) has effective dates-including any retroactive coverage date-that include the entire period when the person provides services or takes actions regulated by this section. a. Engineering. Foundations must be constructed in accordance with complete plans and specifications prepared, signed and sealed by a RLPE. The plans and specifications must be prepared specifically for the site of the work, and they must meet criteria as to scope, content and form specified by the building official. If there are existing trees (either to remain or to be removed) within 20 feet of a foundation, the RLPE must acknowledge, in writing, that the trees have been taken into account in the preparation of the plans and specifications. b. Basic standards. Each foundation must be an approved basic type listed in the following chart. In addition, the design of each foundation must be supported by a geotechnical report and special engineering certification, to the extent indicated in the following chart. r-I a~ a TABLE INSET: Approved Basic Types. See Note Geotechnical Report. Special Engineering 1. See Notes 2 and 3. Certification. See Note 4. Structural slab with void space and Limited Not required deep foundations Structural floor with crawl space and Limited Not required deep foundations Stiffened structural slab with deep Full Required foundations Stiffened non-structural slab with Full Required deep foundations Mixed-depth system for all new Full Required building construction Mixed-depth system for building Full Required additions with deep foundations Another type approved by special As specified in the As specified in the exception issued by the BSC. See below. special exception special exception Note 1. Approved Basic Types . Types of foundations are defined and described in "Foundation Design Options For Residential and Other Low-Rise Buildings on Expansive Soils" published by the Structural Committee of the Foundation Performance Association, Houston, Texas (Document # FPA-SC-01-0, Rev #0, 30 Jun 04, marked "For Website Publishing"), a copy of which is on file in the City Secretary's office ("FDO"). Note 2. Geotechnical Report, Standards. The plans and specifications for each foundation must be based on a written geotechnical report prepared, signed and sealed by a RLGE. The report must cover all testing and site evaluation, and all must meet all applicable criteria in "Recommended Practice for Geotechnical Explorations and Reports" published by the Structural Committee of the Foundation Performance Association, Houston, Texas (Document # FPA-SC-04-0, Rev #0, 11 April 2001, issued for website publishing), a copy of which is on file in the City Secretary's office. The report may be limited as allowed by Note 3 below. The minimum depth of borings is 20 feet in all cases. All required tests and other laboratory work must be performed by an A2LA Lab. Note 3. Geotechnical Report, Scope. "Limited" indicates that the geotechnical testing, evaluation and report may be limited to a determination of the appropriate depth for the deep foundations (but the deep foundation components must meet the other criteria applicable to them). "Full" indicates that the geotechnical testing, evaluation and report must cover all foundation components. Note 4. Special Engineering Certification. Where indicated as "required," for a particular type of foundation, the RLPE must certify that the plans and specifications were prepared to achieve a soil-caused foundation movement potential of one inch or less, and that the RLPE used the estimated depth of the active zone and at least two of the following methods to prepare the plans and specifications: (1) Potential vertical rise (PVR) determined in accordance with Test Method Tex-124-E, Rev. January 1, 1978/December 1982, Texas State Department of Highways and Public Transportation, Materials and Test Division, "Method for Determining the Potential Vertical Rise, PVR" (a copy of which is on file in the office of the City Secretary). For this purpose, the "dry" moisture condition (from which little a shrinkage is experienced, but where volumetric swell potential is greatest) shall be used for each sample and test. (2) Swell tests performed in accordance with ASTM D4546-03, "Standard Test Methods for One- Dimensional Swell or Settlement Potential of Cohesive Soils" as last revised prior to June 1, 2004. (3) Suction and hydrometer swell tests performed in accordance with ASTM D5298-03 "Standard Test Method for Measurement of Soil Potential (Suction) Using Filter Paper" and ASTM D6836-02 "Standard Test Methods for Determination of the Soil Water Characteristic Curve for Desorption Using a Hanging Column, Pressure Extractor, Chilled Mirror Hygrometer, and/or Centrifuge," as such methods were last revised prior to June 1, 2004. c. Foundations, Deep Support Components. Deep support components must be of an approved type. Approved types are listed below. In this list, types of deep support components are defined and described in FDO. (1) Drilled and under-reamed concrete piers. (2) Drilled straight-shaft concrete piers. (3) Auger-cast concrete piles. (4) Another type approved by special exception issued by the BSC. See "h," below. d. Reinforcement. Reinforcement for each foundation must be of an approved type. Approved types are listed below. In this list, types of reinforcement are defined and described in FDO. (1) Deformed bar reinforcing. (2) Another type approved by special exception issued by the BSC. See "h," below. e. Observation and Certification. Each foundation must be professionally observed and must be certified by an RLPE, as more fully described below: (1) Observations must: (i) Be performed either by the certifying RLPE or by one or more persons under that RLPE's direct supervision and control whose professional qualifications are approved by the RLPE (any such person may be an RLGE, with respect to geophysical matters); (ii) Include actual measurement of piers, fill, compaction, reinforcement, forms, materials, dimensions, structural elements, attachments, etc. before the work is covered or concrete is placed (Note: dimensions of an underground element may be measured or estimated from the forms, boring or cavity for the element, before pouring or filling); (iii) Be performed continuously during placement of concrete; and (iv) Be documented in a form and manner approved by the building official (which may include photographs). (2) Certifications must: (i) Refer to and be based upon the professional observations required by this section; (ii) State that the work complies with the plans and specifications last approved by the building official (with any field changes that are ordered by the RLPE and reported to the building official and that comply with applicable regulations); (iii) Comply with criteria as to form and content as maybe specified by the building official; (iv) Be signed and sealed by the certifying RLPE; and (v) Be filed with the building official. (3) Certifications may: (i) Rely in part upon an attached certification by a RLGE, as to geophysical matters; (ii) Rely in part upon an attached certification by an A2LA Lab, as to materials testing; and (iii) Be expressed as a professional opinion based on RLPE's knowledge, information and belief that does not constitute a guarantee or warranty, express or implied. Before framing or other work commences stop a foundation (and before the foundation is otherwise covered), the permittee must obtain written acknowledgment from the building official that the certification for the foundation was duly filed as required above. Certifications, plans, specifications and related items M must be kept on file by the City, available for public inspection, for the retention period required by public cu records laws and may be kept longer (for an indefinite period of time). a r f. Curing concrete. All concrete piers, footings and foundations must be cured for at least 72 hours before any significant load is placed on them. g. Nonhabitable space. This paragraph applies to buildings and additions to buildings that do not contain habitable space (as defined in the IBC). Footings, beams and monolithic slabs with integral footings shall be constructed of masonry or reinforced concrete rated at 2,500 psi @ 28 days (except for accessory buildings with only one story and less than 200 feet of gross floor area). Each building must have footings, beams and slabs of reinforced concrete assuming a soil bearing capacity of 1,500 psi; see R-403 of the IRC. All footings and beams shall be at least 24 inches deep and at least 12 inches wide and shall extend at least 12 inches below the undisturbed soil level. Reinforcement for concrete footings and beams must include at least two #5 deformed bars top and bottom, grade 60 (or better). Slabs must be reinforced with #4 deformed bars, grade 60 (or better), spaced no wider than 16-inches on center each way. Post-tensioned slab or cable foundations are not allowed. h. Special Exceptions. The BSC may issue a special exception from any requirement in subsection "a" through "g," above, but only upon a showing that: (1) the requirement will not affect life safety or the performance of a structure; or (2) an alternate requirement to be imposed by the special exception will provide equal or better protection for life safety and long-term structural performance. However: (i) unless the basic type of foundation is "structural slab with void space and deep foundations" or "structural floor with crawl space and deep foundations," as described in this section, the BSC may not issue a special exception waiving any requirement for an RLPE to have professional errors and omissions insurance, in whole or in part; and (ii) the BSC may not waive any requirement for an RLGE to have such insurance. In connection with any special exception, the BSC may require that the applicant provide supporting engineering data and opinion, and the BSC may impose conditions to carry out the purpose and intent of applicable regulations. 4. Sheathing (gypsum board) and trim must comply with this section, as follows: (1) All walls and ceilings within a R-1, R-2, R-3 and R-4 type occupancy shall be sheathed with Type X gypsum board at least 5/8-inch (15.9 mm) thick. Exception: Where applicable code (IBC, IRC) requires otherwise for moisture protection. (2) All exterior trim (e.g., soffit, fascia, window trim, chimney trim, etc.) must be made of treated lumber or noncombustible materials. 5. Structural elements, engineering, etc. must comply with the following section: A. Scope. (1) The structural elements for the following must meet the criteria in this section, as applicable: (a) Each new building (and each addition to an existing building) containing habitable space and having either a gross floor area of 485 square feet or more or a finished floor height greater than four feet; and (b) Each accessible deck, porch, balcony, walkway and similar structure with a finished floor height greater than four feet. (2) This section does not apply to foundation elements observed and certified under another section. B. Definitions. In this section: Height is measured from the "standard base level" as provided in the Zoning Ordinance. A2LA Lab means a laboratory accredited by the American Association for Laboratory Accreditation on the basis of ISO/IEC 17025:1999 ("general requirements for the competence of testing and calibration laboratories"). RLPE means a registered or licensed professional engineer of the State of Texas who is: (a) Listed with the State Board of Professional Engineers in , W" in the structural branch is required)-; (b) Employed by a registered engineering firm of the State of Texas; and (c) Covered by professional errors and omissions insurance that: (i) has limits of at least $250,000.00 $500,000.00 per claim (and at least $500,000.00 $1,000,000.00 per year, aggregate) and (ii) has effective dates-including any retroactive coverage date-that include the entire period when the person provides services or takes actions regulated by this section. C. Engineering; Plans and Specifications. Structural elements must be constructed in accordance with complete plans and specifications prepared, signed and sealed by a RLPE. The plans and specifications o. must be prepared specifically for the structure in question, and they must meet criteria as to scope, content and form specified by the building official. D. Specific Requirements. (1) Framing, Sheathing. All framing must include full exterior sheathing with structural elements (or blocking) along all joints. The plans must indicate the type, size and spacing of fasteners. All sheathing must be minimum 7/16" structural wood panels. In walls where plumbing, drain, waste or vent lines are located, the framing members must be two inches by six inches or larger. (2) Trusses, Joists, Etc. (a) The species and grade of all lumber used for trusses, joists, purlins, purlin supports or similar elements must be specified in the plans. (b) The length, spacing and direction of trusses and joists must be specified in the plans. (c) Each manufactured wood truss must comply with applicable requirements of the "National Design Standard For Metal Plate Connected Wood Truss Construction" published by Truss Plate Institute (TPI), 1-2000 Ed. The design and specifications of any truss built on the site (and any other truss not already certified as meeting such TPI requirements), must be included in the plans and specifications. (3) Utility-grade lumber may not be used for joists, rafters or vertical framing. (4) Windspeed clips and straps must meet these minimum requirements: (a) Clips: Simpson Strong Tie H2.5 or equal, installed on every other member as follows: rafter to double top plate. (b) Straps/rafters: Simpson Strong Tie LSTA 18 or MSTA 18 or equal installed rafter to rafter over ridge, on every other member. (c) Strap/beams for porches, patios, garage doors: Simpson Strong Tie LSTA 15 or MSTA 15 or equal, installed two on each end of each beam, strapped to post/support. (d) Purlins: Simpson Strong Tie LSTA 15 or MSTA 15 or equal, installed to rafters and spaced no wider than 48 inches on center, also installed on purlin braces and tied to purlins and brace supporting members. E. Observation and Certification. Structural elements must be professionally observed and must be certified by an RLPE, as more fully described below: (1) Observations must: (a) Be performed either by the certifying RLPE or by one or more persons under that RLPE's direct supervision and control whose professional qualifications are approved by the RLPE; (b) Include actual observation of structural elements and attachments in crawl spaces before they are covered by floors or other materials; (c) Include actual observations of each beam, joist, rafter, truss and similar element, including each related weld and high-strength bolt: (i) after all required plumbing, electrical and mechanical "rough-in" inspections havek been passed and all expected "notching," boring and similar work has been done, and (ii) before the item is covered; and (d) Be documented in a form and manner approved by the building official (which may include photographs). (2) Certifications must: (a) Refer to and be based upon the professional observations required by this section; (b) State that the portions of the work required to be observed comply with the plans and specifications last approved by the building official (with any field changes that are ordered by the RLPE, reported to the building official and in compliance with applicable regulations); (c) Comply with criteria as to form and content as may be specified by the building official; (d) Be signed and sealed by the certifying RLPE; and (e) Be filed with the building official. (3) Certifications may: (a) Rely in part upon attached certifications by: (i) an A21LA Lab, as to materials testing, and (ii) an inspector certified by the City of Houston, as to welds or high-strength bolts (or meet the provisions of Section 1704.3.3 1704.3 of the IBC); and (b) Be expressed as a professional opinion based on the RLPE's knowledge, information and belief that Ln does not constitute a guarantee or warranty, express or implied. W on a Before any a beam, joist, rafter, truss, weld, high-strength bolt or similar element is covered: (i) all required city inspections relating to that element must be passed, and (ii) the permittee must obtain written acknowledgment from the building official that the certification for that element was duly filed as required above. For any given building, there may be more than one certification filed. After a beam, joist, rafter, truss, weld, high-strength bolt or similar element has been observed and certified, as provided above, it may not be notched, bored or structurally altered without: (i) a new or amended permit, if required, and (ii) a new observation and certification, in accordance with this section. Certifications, plans, specifications and related items must be kept on file by the city, available for public inspection, for the retention period required by public records laws and may be kept longer (for an indefinite period of time). F. Special Exceptions. The BSC may issue a special exception from any requirement in subsection "A" through "E", above, but only upon a showing that: (1) The requirement will not affect life safety or the performance of a structure (for its estimated useful life); or (2) An alternate requirement to be imposed by the special exception will provide equal or better protection for life safety and long-term structural performance. In connection with any such special exception, the BSC may require that the applicant provide supporting engineering data and opinion, and the BSC may impose conditions to carry out the purpose and intent of applicable regulations. 6. Delete: Appendices A (Employee Qualifications), B (Board of Appeals) and D (Fire Districts). 7. In Section 1612.3, the referenced flood study (with FIRM and FBFM) means the "Flood Insurance Study for Harris County, Texas and Incorporated Areas," dated June 18, 2007 (revision date), with the most effective Flood Insurance Rate Maps and/or Flood Boundary-Floodway Maps (FIRM and/or FBFM) dated June 18, 2007 (map revised date). 8. In Section 3410.2, the blank date shall mean the date of that edition of the IBC, as adopted by the City. 9. If work done on a building within any 12-month period constitutes, cumulatively, a "substantial improvement" (as defined in the City's flood damage prevention ordinances, e.g., Section 18-272 of this Code), the owner shall--to the extent reasonably practicable--make the building comply with current code provisions for new construction regarding: (i) structural components (except foundations) and (ii) life safety features (hand and guard rails, smoke detectors, safety glazing, ground fault circuit interrupters, arc-fault combination breakers, emergency egress from sleeping rooms, locking devices on required egress components, etc.). To determine the "market value" of a pre-existing building, the most current tabulation of square foot construction costs published by the International Code Council (usually as part of "Building Valuation Data." see e.g., www.iccsafe.org/cs/techservices) shall be used. 10. If a building is "substantially damaged" (as defined in the City's flood damage prevention ordinances, e.g., Section 18-272 of this Code), the owner shall cause it to be: (i) secured to prevent entry by unauthorized persons, within 24 hours after all embers are extinguished (or other damaging occurrence has ended) and (ii) either demolished (in accordance with Chapter 18 of this Code) or rebuilt in conformity with applicable technical codes as though it were a new building. Normal permits (including certificate of occupancy) are required. Work to demolish or rebuild must begin within 60 days following the date the occurrence ends and must be completed within a reasonable time, but not longer than the time allowed by the applicable permit(s). To determine the "market value" of a pre-existing building, the most current tabulation of square foot construction costs published by the International Code Council (usually as part of "Building Valuation Data," see, e.g., www.iccsafe.org/cs/techservices) shall be used. (Ord. No. 1775, § 1(app. A), 9-27-2004; Ord. No. 1791, § 1(app. A), 5-2-2005; Ord. No. 1823, § 1, 5-8- 2006; Ord. No. 1824, § 1, 5-8-2006; Ord. No. 1896, § 1, 5-11-2009) ac cc a FPA-SC-04-0 Recommended Practice for Geotechnical Explorations and Reports 11 April 2001 Issued for Website Publishing Foundation Performance Association - Structural Committee Page 1 of 9 RECOMMENDED PRACTICE FOR GEOTECHNICAL EXPLORATIONS AND REPORTS by The Structural Committee of The Foundation Performance Association Houston, Texas Document # FPA-SC-04-0 sSUE HISTORY (Only includes issues outside the Structural Committee) Rev Date Description Subcommittee Subcommittee # Chair Members D 19 Jul 00 Issued for Comments to FPA Ron Kelm Jon Monteith Geotechnical Engineers George Wozny E 21 Aug 00 Issued for Comments to Local Michael Skoller Geotechnical Engineers Moyeen Haque H 4 Jan 01 Re-Issued for Comments to Local Geotechnical Engineers J 1 Mar 01 Issued for FPA Peer Review 0 11 Apr 01 Issued for Website Publishing ' t FPA-SC-04-0 Recommended Practice for Geotechnical Explorations and Reports Issued for Website Publishing Foundation Performance Association - Structural Committee 11 April 2001 Page 2 of 9 PREFACE This document has been developed by a group of Structural Engineers tns goal to attain the geotechnical information they believe ' southeast Texas with the Y is necessary to adequately perform their structural designs. Their need for this document has been prompted by a large number of residential and light commercial foundation problems, some of which have been result, this document has been prepared the subject of litigation. As a specifically for .the Structural Engineers' use. made freely available to the public through the Foundation Performance Association atHowever, it is www.foundationperformanc org so others may have access to the information and may adapt it to their work as they see fit. To ensure the document remains as current as possible, it is intended to be periodically updated under the same document number but with new revision numbers. This document is a recommended practice only and is therefore intended to be neither comprehensive nor a substitute for engineering judgment or for local or standard codes and practices. The user should recognize that there is always the possibility this recommended practice might not be fully adaptable to the site being investigated and in those cases, the use of engineering judgment will be paramount. The intent of this document is to detail certain minimum requirements recommended for the geotechnical exploration and report, thereby ensuring that the Structural Engineer receives the information needed to perform an adequate foundation design. Thus, Geotechnical Engineers preparing proposals for a geotechnical exploration and report in accordance with this recommended practice must all follow certain minimum proposal requirements, which can help ensure a more uniform selection process during the procurement of their services. In requiring the use of this recommended practice, the participating Structural Engineers understand that the request for the information specified herein would most likely increase the cost of the geotechnical work, since there is no intent to delete any of the work currently being executed in the r geotechnical industry. However, they should also realize that this additional cost is necessary in order for them to better understand the soil characteristics of the site on which they plan to design a foundation. When using this recommended practice, it is expected that the Client will provide a description of the foundations and structures proposed for the site. In addition, the Client should provide site plans that show the foundation outline(s), the foundation location(s), and the location and species of any trees that are planned to be removed and that have trunk diameters equal to or greater than 6 inches. If the lots are Wooded Lots, it is intended that the Client will provide a tree survey to the Geotechnical Engineer, showing the location, sizes, species and condition of the trees on each lot. The Client should not discount this requirement as something less than a necessity. Though not recognized locally to be a problem as recently as ten years ago, trees in this area are now known or at least suspected to be the main contributor in the majority of foundation problems in the local market. Therefore the recommendations addressing trees should not be taken lightly. t~ FPA-SC-04-0 Recommended Practice for Geotechnical Explorations and Reports 11 April 2001 1 sued for Website Publishing Foundation Performance Association - Structural Committee Page 3 of 9 This recommended practice addresses a geotechnical report prepared specifically for foundation design and construction. In new subdivisions, the type of geotechnical report that addresses the streets and utilities is not acceptable as a substitute for the work specified herein. Preferably, the borings for a new subdivision should be taken after the streets are cut and the lot's fill is compacted. If however, the geotechnical exploration is made before the streets are cut, then it is the intent of this recommended practice that a separate exploration will later. be procured in order to verify the required density, moisture content, and Atterberg limits for the fill material. This recommended practice is written specifically for use in Houston and the general southeast area of Texas. Therefore, it should be used with caution if utilized elsewhere or if adapted for foundations other than those supporting residential or light commercial structures. The main purpose of this recommended practice is to bring certain minimum requirements together into one document for local Structural Engineers to use in part or in whole, as they see fit. It is not meant to imply that problems will not occur if geotechnical explorations and reports comply in part or in whole with this recommended practice. The Foundation Performance Association and its members make no warranty regarding the recommendations contained herein and will not be liable for any damages, including consequential damages resulting from the use of this document. I DEFINITIONS I For the purpose of this document, the following definitions apply: wilder-The general contractor responsible for performing the construction of the foundation, including the site work. Client - The person or company using this recommended practice in the procurement of the geotechnical exploration and report. Geotechnical Engineer - The engineer or engineering firm responsible for performing the geotechnical exploration and for providing a report of the results. Structural Engineer - The engineer or engineering firm responsible for performing the structural design of the foundation. Wooded Lot- A lot that contains at least one tree per thousand square feet (1 per 1000 SF) of lot area, with those trees having trunk diameters greater than or equal to 6 inches. Note that the trunk diameter measurement is intended to be made at approximately chest-height above the ground level. Although the proper term for tree stem diameter in arboriculture is "caliper", that term is purposely not used herein because it is sometimes confused with "circumference" when measuring trees. FPA-SC•04-0 Recommended Practice for Geotechnical Explorations and Reports 11 April 2001 Issued for Website Publishing Foundation Performance Association - Shctural Committee Page 4 of 9 TABLE OF CONTENTS 1.0 MINIMUM CRITERIA 1.1 General 1.2 Site Exploration 1.2.1 Area Reconnaissance 1.2.2 Borings Quantities and Locations 1.2.3 Boring Depths 1.2.4 Sampling Frequency 1.2.5 Field Testing and Logging 1.3 Laboratory Testing 1.4 Reporting 2.0 SPECIAL REQUIREMENTS 2.1 Slab-on-Grade Design Parameters 2.2 Drilled Piers Design Parameters 2.3 Suspended Slab Design Parameters 2.4 Select Fill Parameters FPA-SC-04-0 Recommended Practice for Geotechnical Explorations and Reports 11 April 2001 Issued for Website Publishing Foundation Performance Association - Structural Committee Page 5 of 9 1.0 MINIMUM CRITERIA The following subsections outline the Geotechnical Engineer's minimum requirements in accordance with this recommended practice. 1.1 General The Geotechnical Engineer should provide the Structural Engineer and Builder with sufficient information to enable them to: (a) design a structural foundation that is appropriate for the site conditions and is capable of adequately supporting the given building design loads, (b) provide a safe foundation design that meets local code and professional standards, and (c) carry out the site work and foundation construction in a safe and efficient manner. The Geotechnical Engineer should advise the Client if any requirements herein are in direct conflict with local codes and professional standards. In addition, the Geotechnical Engineer should carry out the work and prepare the report with the assumption that the Structural Engineer will never actually see the site for which the foundation will be designed. 1.2 Site Exploration It is the Geotechnical Engineer's responsibility to investigate the site as required to comply with local codes, professional standards and the requirements of this recommended practice. In addition, the site exploration should include the following minimum criteria: 1.2.1 Area Reconnaissance The Geotechnical Engineer should check the area of the building site and the area surrounding the site for any anomalies such as streams, ponds, fill, dumps, existing above-grade gtn,ctures, escarpments, slopes, poor draining areas, seeps, cutcrops,'.: rge trees, !ree stumps, erosion, structures, roadways, railways, areas that appear to be wetlands, or anything else that will help the Builder and Structural Engineer understand the prior and present land use of and around the site. Representative color photos of the site should be recorded at the time of the site exploration and should be included in the final report. Where possible, the photos should include portions of the properties adjacent to the site. All anomalies, including trees and tree stumps with trunks equal to or greater than 12 inches diameter should be located on the boring plan. On Wooded Lots the Geotechnical Engineer should superimpose the data from the Client-supplied tree survey on his plans. 1.2.2 Boring Quantities and Locations a. For new residential subdivisions that are anticipated to have grade-supported foundations, at least one boring per 5 lots is recommended, but not less than one boring every two acres. b. For new residential subdivisions that are anticipated to have pier-supported foundations, at least one boring per lot is recommended. c. For individual residential lots or for properties with light-commercial buildings, one boring for every 2,500 square feet of building ground floor slab, but a minimum of two 1 FPA-SC-04-0 Recommended Practice for Geotechnical Explorations and Reports Issued for WebsifE Publishing Foundation Performance Association - Structural Committee 11 April 2001 Page 6 of 9 borings for the lot. The borings should be taken inside the projected building perimeter or as close as possible, if obstructions exist. d. For lots with predominately cohesive soils and with trees growing within 25 feet (even if located on adjacent property) of the proposed foundation, one boring should be taken within 10 feet, or as close as possible, of the largest tree having a trunk size equal to or greater than 12 inches diameter, even if this dictates an additional boring for the lot. e. For additions of less than 1000 square feet, one boring is adequate, except that the boring should be taken within the proposed foundation area and the recommendations in Paragraph 1.2.2d are still applicable. 1.2.3 Boring Depths Boring depths below are measured from the grade existing at the time of the site exploration. a. The minimum depth of every boring should be 20 feet. However, if the upper 10 feet are predominately cohesionless, then the minimum depth may be reduced to 15 feet. b. On Wooded Lots, or lots containing one or more trees with trunks equal to or greater than 12 inches diameter, and if these lots contain predominantly cohesive soils, borings should be a minimum of 25 feet depth. c. For sloped lots, where the proposed foundation is to be situated at a height H above the toe of an embankment (or estimated toe if submerged), if the horizontal distance from the foundation to the toe is less than 4H, then the depth of borings recommended should be a minimum of 2H. 1.2.4 Sampling Frequency a. Undisturbed samples should be taken at a minimum of 1-ft, 2-ft, 4-ft, 6-ft, 8-ft, 10-ft, 12-ft, 164% 20-ft depths, and thereafter at a maximum of 5-ft iuiervals. b. If fill is known to have been placed on the site, sampling frequency should be increased to one sample per foot in the fill regions. c. A sample should also be taken at the bottom of the borehole. 1.2.5 Field Testing and Logging a. Each sample should be visually classified and logged during retrieval. b. Existence and depth of roots should be noted. c. Hand penetrometer testing should be done and reported on all cohesive samples. d. Standard penetration testing should be done and reported on all cohesionless samples. e. After the borehole is complete, measurements of the free water surface should be made and logged at completion of the borehole, and then again upon completion of the sitework, with that time interval being reported. 1.3 Laboratory Testing The Geotechnical Engineer should perform sufficient laboratory testing to comply with the requirements of standard codes and local practices. However, the following laboratory testing is recommended as a minimum; FPA-SC-04-0 Recommended Practice for Geotechnical Explorations and Reports 11 April 2001 Issued for Website Publishing Foundation Performance Association - Structural Committee Page 7 of 9 a. Existence and depth of roots or root fibers should be observed and reported for each soil sample. b. Moisture contents should be performed on all samples retrieved. c. In cohesive soils, Atterberg testing should be performed on a minimum of one third of the samples retrieved, with emphasis towards the upper strata. Reports should include plastic limits, liquid limits, and plasticity indices. d. In cohesive soils, the percentage of clay (minus 2 microns) should be tested using a hydrometer. e. Cohesive samples at the recommended foundation bearing depths may be tested using the torvane testing device provided a baseline test is made using unconfined compression tests for comparison. f. For lots that have predominately cohesive soils, testing at each boring location should be done to determine soil suction. Soil suction tests should be conducted using the transistor psychrometer method, the filter paper method or other methods that give similarly reliable suction values. Where suction testing is recommended, it should be done at sample depths of 2-ft, 44, 6-ft, 8- ft, 10-ft, 12-ft, 16-ft and 20-ft, but may be terminated earlier at the depth of constant suction, if determined. 1.4 Reporting The Geotechnical Engineers may use their own standard reporting techniques. However, the final report should also contain the following where applicable: a. A statement confirming that the geotechnical exploration and report are in accordance with the requirements of this recommended practice. If any exceptions are taken, the report should note each exception and the reason for taking the exception. b. A general description of the site and surrounding properties, specifically addressing the anomalies as discussed in Paragraph 1.2.1. c. Color photos of the proposed building site and where possibie, adjacent properties. A minimum of two photos is recommended, but the total number of photos should at least be equal to the total number of borings. d. A plot plan showing the approximate location of borings, tree trunks equal to or greater than 12 inches diameter and all anomalies as described in Paragraph 1.2.1. In the case of trees, include species where known, the condition of the tree if not healthy (i.e., "dying," or "dead") and show trunk diameters, measured at chest-height. If the site personnel are unable to identify the tree species, then an attempt should be made to classify them into categories that help the user to estimate the potential water usage of the tree. For example a tree could be classified as either a hardwood or pine. Alternatively, it could be classified either as a broadleaf or conifer. e. Boring logs that include all field and laboratory tests results, unless particular data is presented on other charts or tables. f. Descriptions and classification of the materials encountered. g. Elevation of the water table, if encountered. If no water was encountered, the report should state that the holes were "dry". h. Provisions to mitigate the effects of expansive soils. i. Recommendations on earthwork stabilization requirements (including requirements for slope stability) needed to prepare the site before the foundation can be constructed. t FPA-SC-04-0 Recommended Practice for Geotechnical Explorations and Reports 11 April 2001 Issued for Website Publishing Foundation Performance Association - Structural Committee Page 8 of 9 J. A discussion on foundation maintenance required in order to maintain the design. k. Combined (i.e., for the various borings) plots of moisture content profiles and plastic limit profiles vs. boring depths. 1. Plots or tables showing the percentage of clay in cohesive samples as determined from hydrometer testing. in. A discussion of the degree of saturation or desiccation of the site as compared to the estimated equilibrium moisture contents of the samples. This can be presented graphically depending on the method used (e.g., a graph of moisture content minus plastic limit vs. depth). n. Combined (i.e., for the various borings) plots of suction values vs. boring depths. o. Interpreted output from the suction testing including the moisture active depth, the movement active depth, the edge moisture variation distance and the probable vertical movement, both up and down, of the ground surface. p. Specific discussion of trees to be removed before construction and of trees that are to remain after construction is complete, if known. 2.0 SPECIAL REQUIREMENTS In addition to the general minimum criteria discussed above, there are some specific requirements that may be applicable to the Geotechnical Engineer, depending on the Client's needs. These requirements are as follows: 2.1 Slab-On-Grade Design Parameters Regardless of the type of building foundation planned, if design recommendations are provided for slab-on-giadc foundai;otis, then the Geotechnical Engineer should provide recommendations as outlined in both (a) WRI's "Design of Slab-on-Ground Foundations," latest edition and (b) PTI's "Design and Construction of Post-Tensioned Slabs-On-Ground," latest edition. 2.2 Drilled Piers Design Parameters If design recommendations are requested or made for drilled piers such as those recommended for slab-on-piers (at grade), suspended (structural) slabs, or structural floor-on-piers (i.e., with a crawl space) foundations, then the Geotechnical Engineer should provide recommendations for pier depth that takes into account possible upward and lateral movements as well as the normal downward movement due to gravity loads. Upward movement should be addressed if the soil is predominately cohesive. Lateral movement should be addressed if the site has pronounced slopes or if substantial fill is planned or has already been placed. In addition, the Geotechnical Engineer should also provide similar design recommendations as specified in Paragraph 2.1. Further, allowable design loads and recommended depths should be provided for both (a) drilled and under-reamed piers and (b) drilled straight shaft (skin friction) piers, in order to give the Client an opportunity to perform or obtain a cost/benefit study. FPA-SC-04-0 Recommended Practice for Geotechnical Explorations and Reports 11 April 2001 slued for Website Publishing Foundation Performance Association - Structural Committee Page 9 of 9 I 2.3 Suspended Slab Design Parameters if design recommendations are requested or made for the entire slab to be suspended above the soil using a structural slab system, the report should prescribe the recommended void box height. In this case, the report should also advise the maximum possible heave the surface of the soil could experience if the site is exposed to an unlimited source of moisture. 2.4 Select Fill Parameters On sites that require select fill be added to reduce the expansiveness of the in-situ soil, the Geotechnical Engineer should provide several options (e.g., different thickness of select fill1natural soil removal combinations versus potential heave/subsidence) that will allow the Client an opportunity to perform or obtain a cost/benefit analysis.