R value state local al alabama 2015 alabama commercial energy code 2 r 25 3 r 25 state local ak alaska 2012 alaska building energy efficiency standard 7 r 35 8 r 35 9 r 40 local only az arizona no statewide mandated r values phoenix 2012 iecc yuma 2009 iecc tucson 2012 iecc flagstaff 2009 iecc 2 r 20 2 r 20 2 r 20 5 r 20 state only.
Flat roof u value 2017.
Reference table for u values u value is the coefficient of transmission i e the transmission of heat through the materials which compose the building s envelope or outer shell.
Column b is for other extensions upgraded existing thermal elements non exempt conservatories and conversion of unheated.
All structural metal roofing systems having a thickness equal to or greater than 22 gage and all.
Roof coverings installed on low slope roofs roof slope 2 12 in accordance with section 1507 shall resist impact damage based on the results of tests conducted in accordance with astm d3746 astm d4272 cgsb 37 gp 52m or the resistance to foot traffic test in section 5 5 of fm 4470.
0 25 column a is for extensions where the existing dwelling s walls and roof u values are worse than 0 70 w m k in the walls and worse than 0 25 w m k in the ceiling.
U value has an inverse relationship to r value.
For example a building with material with an r value of r 11 converts to an u value of 0 09 1 r or 1 11 0 09.
The thermal transmittance or u value of the complete roof system is calculated in accordance with established international standards.