# Workshop Question Dated 8/10

**URL:** <https://community.blackspectacles.com/t/workshop-question-dated-8-10/7450>\
**Category:** Project Development & Documentation\
**Created:** [August 17, 2025, 6:38pm UTC](https://community.blackspectacles.com/t/workshop-question-dated-8-10/7450 "2025-08-17T18:38:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![sh.khodabakhshi](https://yyz1.discourse-cdn.com/flex029/user_avatar/community.blackspectacles.com/sh.khodabakhshi/32/1097_2.png) [@sh.khodabakhshi](https://community.blackspectacles.com/u/sh.khodabakhshi)\
**Post date:** [August 17, 2025, 6:38pm UTC](https://community.blackspectacles.com/t/workshop-question-dated-8-10/7450/1 "2025-08-17T18:38:50Z")

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@christopherbwatkins92 Hello Chris,

Thank you so much for your great presentation! I learned a lot and really appreciate it.

Regarding question 1 of part 3, the question asked about the **U-Value** , but we added up all **R-values** , and our number **18.075** was an **R-value** , not a U-value. Also, it states the **R-value of the full cavity is 19**.

To calculate the U-value, do we need to do (1/18.075) + (1/19) = 0.6 U-value? Is this not the answer to the question? Could you please clarify this?

Thanks again!

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**Author:** ![kiaragalicinao](https://yyz1.discourse-cdn.com/flex029/user_avatar/community.blackspectacles.com/kiaragalicinao/32/1607_2.png) [@kiaragalicinao](https://community.blackspectacles.com/u/kiaragalicinao)\
**Post date:** [September 3, 2025, 10:34pm UTC](https://community.blackspectacles.com/t/workshop-question-dated-8-10/7450/2 "2025-09-03T22:34:10Z")

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Hi @sh.khodabakhshi,

I think you meant to tag @coachchrishopstock 🙂 I’m glad you found his PDD Virtual Workshop: _Exterior Wall Assemblies: Detailing & Best Practices_ helpful!

While the question asks you to calculate U-Value, the figures provided for each material is given in R-Value (which is typical in practice). You would first take the sum of all relevant R-Values from the worksheet (18.075). Then, knowing that U-Value is the inverse of R-Value, you would calculate 1 / 18.075 to get a U-Value of .055.

While the insulation is R-19, the actual R-Value of insulation + 6” metal studs @ 16” O.C. is 7.1 (as indicated in the worksheet). This component of the wall assembly is already factored into the R/U-Value calculation above.

Hope this helps!

Kiara Galicinao, AIA, NCARB  
Product Coordinator  
**[Black Spectacles](https://www.blackspectacles.com/en-us/)**