R Value for snow loads in Tedds

[dmersim]

Hello,

I have a question about the R value (Thermal Resistance) in Tedds when referencing ASCE 7-05.
How do you calculate it? My Ct value is 1.00 but i dont see a way to calculate thermal resistance which is defaulted at 30 in Tedds.

Sorry if my formatting isnt correct this is my first post on eng tips.

Thanks

 

[jimstructures]

Could you give us some more information on what Tedds is asking for when it is calculating some thermal resistance due to Snow Load on a building, etc.

I was not aware that there was any capability to add thermal resistance due to snow load.

Jim

 

[dmersim]

Heres a picture of the menu where it asks for R

 

[flight7]

Tedds is asking for the R-value of the roof insulation. This goes into calculating the Warm Roof Slope Factor Cs in Figure 7-2 of ASCE 7. Your architect should be able to tell you what the R-value is on your project.

 

[dmersim]

okay, as a followup question - If i already know my Ct value, how does the R value effect my snow load?

 

[jimstructures]

If you have a normal heated building with a high R value it is going to slow down the heat loss through the roof of the building, especially if you have also chosen a ventilated roof surface. In other words the snow might take a long time to melt off and the snow load on the roof will remain in place along time.

Jim