Question:
Is it the intent of R301.2.1.1 to allow engineered design for roof deck thickness?
Comment:
Want to design roof deck thickness in accordance with approved standards and Code in lieu of prescribed Table R803.2.2.
Existing Interpretations and/or Declaratory Statements Related to this request
Input Received:
Which one of the six methods is the designer stating they will utilize for wind load design where the wind speed equals or exceeds 115mph?
The 7th Edition Code Change Analysis clarifies this question. The wind design required section has been reorganized to clarify which provisions of the code are applicable to various construction methods. The prescriptive provisions for low wind areas in Chapters
5, 6, and 8 have been deleted. Wind design requirements in the FBCR are generally unchanged but the code now makes it clear which provisions apply. ICC 600 is now only permitted to be used for the design of concrete and masonry walls. Wood frame roofs are required to be designed in accordance with ASCE 7 or in accordance with the AWC WFCM. New exceptions specifically reference applicable sections in the code for the design of footings and foundations, windows and doors, SIPs, wall coverings, roof sheathing, roof coverings, and insulated concrete form construction. Concurrently, section/ table R803.2.2 was added outlining the minimum roof sheathing thickness required per wind speed. As the outlined references in R301.2.1.1 are to be used for the overall design, based on wind, the remaining sections, and tables of the code still apply to the specific elements, such as roof sheathing thickness.
The answer is no, the engineer cannot call out a sheathing thickness that does not meet the minimum required in R803.2.2
Answer:
The 7th Edition Code Change Analysis clarifies this question. The wind design required section has been reorganized to clarify which provisions of the code are applicable to various construction methods. The prescriptive provisions for low wind areas in Chapters 5, 6, and 8 have been deleted. Wind design requirements in the FBCR are generally unchanged but the code now makes it clear which provisions apply. ICC 600 is now only permitted to be used for the design of concrete and masonry walls. Wood frame roofs are required to be designed in accordance with ASCE 7 or in accordance with the AWC WFCM. New exceptions specifically reference applicable sections in the code for the design of footings and foundations, windows and doors, SIPs, wall coverings, roof sheathing, roof coverings, and insulated concrete form construction. Concurrently, section/ table R803.2.2 was added outlining the minimum roof sheathing thickness required per wind speed. As the outlined references in R301.2.1.1 are to be used for the overall design, based on wind, the remaining sections, and tables of the code still apply to the specific elements, such as roof sheathing thickness.
Commentary:
The engineer cannot call out a sheathing thickness that does not meet the minimum required in R803.2.2
