Q&A with Stephen DiGiovanni, chairman of AdHoc Committee on Tall Wood Buildings

Stephen DiGiovanni, PE, chair of the International Code Council (ICC) Ad Hoc Committee for Tall Wood Buildings, answered questions about his role with the committee and some of the challenges he and the group have faced.


Figure 3: Brock Commons Tallwood House, Acton Ostry Architects. Courtesy: naturally:wood | Photo: Michael Elkan PhotographyStephen DiGiovanni, PE, currently serves as chair of the International Code Council (ICC) Ad Hoc Committee for Tall Wood Buildings. He earned a Bachelor of Science degree in fire protection engineering from the University of Maryland, College Park, and is a licensed fire protection engineer in California and Nevada. DiGiovanni currently resides in Las Vegas, where he is employed by the Clark County Department of Building and Fire Prevention. Clark County is approximately 8,000 sq miles, predominately rural in nature, save for unincorporated areas within the Las Vegas Valley including the famed Las Vegas Strip. Nicholas A. Moriarty, executive director of fire protection with NV5 interviewed DiGiovanni regarding his role with the committee.

Moriarty: What's your role with the committee and how did you get involved?

DiGiovanni: I was selected to be a committee member because of my experience with high-rise construction and previous work I had done on tall wood buildings for the ICC Fire Code Action Committee (FCAC). I was ultimately was selected to serve as the committee chair. The committee is comprised of architects and engineers, material specialists, testing laboratory representatives, building and fire code officials, and the fire service. Committee members vary in experience with the ICC code-development process, mixing veterans of the code-development arena along with those new to the process of developing codes for potential adoption. Committee work was documented through the ICC website.

Moriarty: What construction type is this and how did the committee approach the issue?

DiGiovanni: As we addressed the construction features of these three new construction types, Type IV-A, IV-B and IV-C, there were several aspects that required additional attention. First, I am reminded of the first presentations back in our initial meeting, where one of the presenters summarized the concept of a tall wood buildings as one where all code-requirements that are typically required of Type I buildings, including fire-resistance ratings and structural requirements, can be met by mass timber, except for the fact that wood is combustible-that was it. So the committee spent a great deal of time addressing the combustibility of this construction type, thus reducing the contribution of the mass timber to a fire, and requirements for noncombustible protection, ostensibly by way of attaching two or more layers of gypsum to surfaces of mass timber. Second, there was concern about the adhesives used in cross-laminated timber (CLT) manufacturing. The committee worked with industry members to address adhesives, and now the industry standard for CLT, ANSI/APA PRG 320-2018: Standard for Performance-Rated Cross-Laminated Timber, has been updated to provide increased testing requirements for adhesives. Finally, the proposals introduce the use of combustible exterior walls and concealed spaces to Type IV construction. To accomplish this, the committee wrote in requirements to protect the exterior surfaces of walls and interior surfaces of concealed spaces.

Figure 5: Shown here is a photo of cross laminated timber production. Courtesy: naturally:woodMoriarty: What was the biggest challenge the committee faced?

DiGiovanni: The biggest challenge, however, has been the development of height and area proposals. The height and area tables that exist in the code have been derived over many decades from a combination of qualitative and quantitative analysis. Because of this, there is no formula or prescribed method for introducing new construction technologies into the code. It's not as if a test exists where results are used to output the height or square footage. The committee approached this issue by determining which of the proposed construction types provided performance similar to what is expected of Type I-B construction, and then using professional judgment to build height and area allowances for all three proposed construction types.

Moriarty: What impact has your involvement in the committee had on you as a fire protection engineer?

DiGiovanni: At the end of it all, my feelings have not wavered much. I've always believed that if a material can provide equal performance in all aspects, then the material should be permitted equal use in the code. All materials have their strong suits and their weak points, and if the weaknesses are addressed by the required provisions, I feel all materials have their usefulness. I've always been open to the use of wood for taller buildings, so long as I can be convinced that the building performance is not hampered in any way by the material properties. It is my belief that there is a place in the codes for mass timber in high-rise construction, so long as the detailed requirements for construction are provided for and the weaknesses of the material-again, mostly revolving around the fact that wood is combustible-are addressed.


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