Special Inspections Pitfalls - Part I

A pitfall is defined as a particular activity or situation where things go wrong or may cause problems. Project special inspections certainly have a fair share of potential pitfalls during building construction phases regarding all of the disciplines that comprise the construction schedule. For whatever reason, there are times when certain code-required special inspections are not accomplished on a project or performed properly. Some of these reasons are as follows:

1.???? The statement of special inspections did not list the particular special inspection

2.???? The registered design professional was not aware of the required special inspection

3.???? The building official did not know that the code- required special inspection existed

4.???? A special inspection agency was never contacted to provide the special inspection

5.???? The contractor did not realize that the special inspection was required

6.???? The special inspector was notified too late and items requiring special inspection are covered up by other construction elements

7.???? The special inspector was not aware that the particular special inspection was required

8.???? International Building Code (IBC) required special inspections are exempted by statewide codes

9.???? The special inspection or related test was not performed accurately

There are numerous other reasons why code-required special inspections are not provided on project work. One of the primary reasons that special inspections are overlooked is the sheer volume of special inspections and the numerous sources of code-acceptance criteria. There are hundreds of model

codes and standards that specify code-required special inspections and thousands of pages to review to determine what specific special inspections are required involving specific disciplines and various structural elements of a building. There are also dozens of different special inspections required on nonstructural elements of buildings and structures.

Read on to learn more about common special inspections pitfalls!

GEOTECHNICAL ENGINEERING AND SOILS SPECIAL INSPECTIONS

PITFALL 1: The geotechnical report fails to include the number and frequency of field tests on compacted fill material required to determine compliance related to the maximum dry density of compacted fill.

RESPONSE: IBC code Chapter 18, Section 1803, requires that the geotechnical report include the number and frequency of field tests during earthwork operations.

PITFALL 2: The geotechnical report addresses concrete slab-on-grade but does not recommend minimum slab thickness or a polyethylene vapor barrier.

RESPONSE: IBC code Chapter 19, Section 1907, does require that the thickness of a concrete floor slab supported directly on the ground shall be not less than 3 ? inches thick and that a 6-mil polyethylene vapor barrier be placed between the base course or subgrade and the concrete floor slab. This IBC code section does allow equivalent methods and lists some exceptions.

PITFALL 3: The soils special inspector on a large earthwork project is inspecting and testing the compacted fill beneath the building and has not read and does not have a copy of the approved geotechnical report written by another firm not associated with the soils special inspector.

RESPONSE: IBC code Chapter 17, Section 1705.6, states, “During fill placement, the special inspector shall verify that proper materials and procedures are used in accordance with the provisions of the approved geotechnical report.” The load-carrying capacity of the supporting soil has a significant impact on the structural integrity of any building. Proper compaction, lift, density, and compliance with the geotechnical report’s recommendations are critical to achieving the design bearing capacity.

CONCRETE SPECIAL INSPECTIONS

PITFALL 1: The concrete special inspector consistently fabricates concrete test specimens on the project site as required by the code and the contract documents but fails to provide proper initial curing required by the code in the field (temperatures of 60F to 80F). They do not achieve these temperatures until the test specimens arrive in the laboratory.

RESPONSE: ASTM C 31, “Standard Practice for Making and Curing Concrete Test Specimens in the Field,” mandates that immediately after molding and finishing, the specimens shall be stored for a period of up to 48 hours in a temperature range from 60F to 80F and in an environment preventing moisture loss from the specimens. ASTM C 31 is adopted by the IBC and listed in IBC Chapter 35. The failure of the special inspector to provide proper initial curing of concrete test specimens is non-compliant with ASTM C 31, the IBC code, and the contract documents.

PITFALL 2: A concrete special inspector providing special inspections in the field, relative to the fresh plastic concrete, performs various concrete inspections and tests but rarely checks out the concrete truck delivery ticket. Should the concrete special inspector observe and examine the concrete delivery ticket?

RESPONSE: Yes, the concrete special inspector should review each truck’s concrete delivery ticket for numerous concrete code acceptance issues. IBC Chapter 17, Table 1705.3, inspection type #5, instructs the special inspector to review the concrete delivery ticket to assist in “verifying the use of the required design mix.” The Table 1705.3 reference standard column pertaining to inspection type #5 explicitly lists all of ACI 318, Chapter 19, and ACI 318, Sections 26.4.3 and 26.4.4, which invoke monitoring the concrete ticket for concrete mix ID, strength classification, concrete exposure class classification, mix proportions, and much more.

PITFALL 3: Does the code require inspection of the concrete reinforcing steel as a special inspection item?

RESPONSE: The IBC code does require periodic special inspections on concrete reinforcing steel and elaborates on the subject in IBC Chapter 17, Table 1705.3, inspection type #1. Table 1705.3 invokes all of ACI 318, Chapter 20, which addresses steel reinforcement and specific sections (25.2, 25.3, 26.6.1 thru 26.6.3) of ACI 318, Chapters 25 and 26. These code sections address concrete cover, rebar spacing, hooks, bends, stirrups, and rebar placement tolerances. In addition to code-required concrete rebar special inspections, the special inspector should always be familiar with the requirements of the contract documents and enforce those as well. Most contract documents require that concrete reinforcing steel be placed in accordance with Concrete Reinforcing Steel Institute (CRSI) standards.

MASONRY SPECIAL INSPECTIONS

PITFALL 1: Does the code require that the special inspection agency actually test the concrete masonry units (CMU), mortar, and grout during construction phases of a project, OR are approved submittals (certificates of compliance) on each of these materials satisfactory?

RESPONSE: This is a good question, and we hear it a lot. The answer is that several articles within TMS 602 (masonry code) require actual testing of these materials. Table 3 of TMS 602 requires verifying f’m (specified compressive strength in psi of clay or concrete masonry) before construction except where exempted by the code. Articles 2.1, 2.2, and 2.3 of TMS 602 require compliance testing of mortar, grout, and masonry units according to ASTM C 270, ASTM C476, and ASTM C C 90, respectively, and field strength tests are the only practical method to verifying code- required strengths. TMS 602, Table 4, entitled “Minimum Special Inspection Requirements,” also requires unit strength testing of masonry materials according to Article 1.4 to verify compressive strengths.

PITFALL 2: Is the masonry special inspector required by the code to do any particular type of special inspections regarding the masonry mortar joints during masonry construction?

RESPONSE: Yes, Article 3.3 of TMS 602 offers several types of code-required inspections that the special inspector in the field should provide during masonry construction. Article 3.3 B(2b) specifically requires that the mason tool the mortar joint when mortar is “thumbprint hard” unless otherwise required. Article 3.3B(2c) requires that the mason remove mortar protrusions extending ? inch or more into cells or cavities to be grouted. Article 3.3 also offers code-required verbiage related to the size of mortar head and bed joints and tolerances on the mortar joint sizes. The special inspector should verify all.

STRUCTURAL STEEL WELDING SPECIAL INSPECTIONS

PITFALL 1: Complete joint penetration welds (CJP) require ultrasonic testing (UT) according to the AISC 360 code. There is hardly ever any question about this fact regarding full penetration welds. The question that often arises during project work is, “Can the welding special inspector provide the code- required UT testing on welds through the paint when the welds to be tested involve steel and welds that have been painted?”

RESPONSE: The short answer is no; AWS D1.1, clause 6.25, states, “All surfaces to which a search unit (UT machine) is applied shall be free of ... paint, and loose scale and shall have a contour allowing intimate coupling.”

The AWS D1.1 acceptance standard for shear wave analysis (UT testing) of complete and partial joint penetration welds is clause 6.25.8, Table 6.2 or 6.3, based on the indication rating of the reflected signal generated. The signal produced by the transducer is sent into the base metal and reflected at a given angle through the weld metal. A discontinuity will reflect the sound, which is then analyzed for its return strength. This returned signal is compared to the reference level set before testing to develop an indication rating. (Code verbiage can be nebulous at times.)

So what?

Paint in the system would deaden the sound! The signal from the transducer would have to pass through the paint, into the base metal, to the weld, and then back through the base metal and paint again to reach the transducer. The sound signal is reduced with two trips through the paint, so your indication rating is no longer accurate. If you increase the paint thickness, the sound return is even more reduced.

In addition to the loss of return signal, the dimensions that the UT machine is calculating for the time of flight of the sound signal are distorted by differing angles of reflection/refraction of the sound to transducer and sound to base metal interfaces, changing everything!

So, if you are attempting a shear wave inspection of welds according to AWS D1.1 requirements, ensure a clean, bare metal surface to test from, which means NO paint.

There are dozens of special inspections pitfalls that can come into play on almost every construction project nationwide. That is because no single architect or structural engineer can be aware of all of the code-required special inspections of each project discipline—geotechnical, soils, concrete, reinforcing steel, masonry, structural steel, sprayed fire-resistant materials (SFRM), cold-formed steel, wood, seismic force-resisting elements, etc. Similarly, no project special inspector, building official, or contractor can know all potential project special inspections required by the hundreds of building codes and standards. However, when the entire project team works together in total unison toward detecting code discrepancies and construction resolutions, the integrity of the construction and code compliance is more assured.

Since the research for this “pitfall” topic turned up so many varied construction code situations, we will issue a part two for this article at a later date. Stay tuned!

But wait! We have a lot more to say! For a complete picture of the Code and how it relates to Special Inspections, F&R would love to provide a virtual AIA-accredited Lunch & Learn presentation to the professionals at your firm.

Alan S. Tuck, Director of Code Compliance & Training | T 540.344.7939 | M 540.798.4440 | [email protected]