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Interpretation #8495

Original Request

  • Requested By: Paul Wilburn
  • Requester E-Mail: pwilburn@mulhernkulp.com
  • Code Version: 2021
  • Code: RESIDENT
  • Code Description:
  • Chapter:
  • Section: Table R803.2.2
  • Topic: Minimum Roof Sheathing Thickness

  • Question: In Table 803.2.2 where the required sheathing thickness changes between the designated wind speeds, at what wind speed which falls between the 2 designated wind speeds does this change? As an example for wind speed 140 mph exposure B the sheathing thickness is 7/16 and wind speed 150 exposure B the sheathing thickness is 15/32. What sheathing thickness is required between the 140 mph exposure B and 150 mph exposure B? Can it be 7/16 or does it have to be 15/32?

Answer:

Table R803.2.2 is a prescriptive table, and a registered design professional may calculate a different sheathing thickness considering all site conditions. If you are interpolating between wind speeds, a registered design professional should be consulted to determine the sheathing thickness's adequacy to resist the loads. If a registered design professional is not involved, and you are strictly using the table, the most stringent of the two thicknesses should be applied.
On 12/18/2020 at 4:17 PM

Commentary:

None.