Rim Joists

Modified on Tue, 15 Aug, 2023 at 3:45 PM

Rim Joist Library Help

R-value	The effective thermal resistance value of insulation added to rim/band joists. This should not include the thermal resistance of the exterior rim joist itself or for siding and air films, those are already included. Insulation that is not continuous (e.g. joist bays) should be discounted using the Area Weighted Average method. Continuous and cavity insulation values should be added together. All R-Values are in I-P (US) units: (h-ft2-F)/Btu, and were calculated using a single stud/cavity layer in our Assembly Wall Calculator with a framing fraction of 0.093 for 16" O.C. and 0.062 for 24" O.C.. Please find some examples below: R-13 Grade I Cavity Insulation, 16" O.C.: R-12.0, Grade II: R-11.1, Grade III: R-9.9 R-13 Grade I Cavity Insulation, 24" O.C.: R-12.6, Grade II: R-11.5, Grade III: R-10.3 R-13 Grade I Cavity Insulation, 16" O.C., Plus R5 Continuous Insulation: R-17.5, Grade II: R-17.0, Grade III: R-16.4 R-13 Grade I Cavity Insulation, 24" O.C., Plus R5 Continuous Insulation: R-17.9, Grade II: R-17.4, Grade III: R-16.7 R-15 Grade I Cavity Insulation, 16" O.C.: R-13.3, Grade II: R-12.2, Grade III: R-10.8 R-15 Grade I Cavity Insulation, 24" O.C.: R-14.1, Grade II: R-12.8, Grade III: R-11.2 R-15 Grade I Cavity Insulation, 16" O.C., Plus R5 Continuous Insulation: R-19.0, Grade II: R-18.4, Grade III: R-17.6 R-15 Grade I Cavity Insulation, 24" O.C., Plus R5 Continuous Insulation: R-19.6, Grade II: R-18.9, Grade III: R-18.1 R-19 Grade I Cavity Insulation, 16" O.C.: R-17.3, Grade II: R-15.4, Grade III: R-13.2 R-19 Grade I Cavity Insulation, 24" O.C.: R-18.1, Grade II: R-15.9, Grade III: R-13.5 R-19 Grade-I Cavity Insulation, 16" O.C., Plus R5 Continuous Insulation: R-22.8, Grade II: R-21.9, Grade III: R-20.7 R-19 Grade-I Cavity Insulation, 24" O.C., Plus R5 Continuous Insulation: R-23.5, Grade II: R-22.5, Grade III: R-21.2
U-factor*	Thermal transmittance factor (inverse of R-value) of insulation added to rim/band joists. Insulation that is not continuous (i.e. joist bays) should be discounted using the Area Weighted Average method. All U-factors are in I-P (US) units: (h-ft²-F)/Btu. For examples, please use 1/R from the R-value section.
Air Sealing	Select the appropriate level of Air Sealing for the assembly. Click the information icon for descriptions of the different options. Most new construction should be designated Tight. This field is only used in Analysis when ‘Use Ekotrope Estimate’ is checked in the Infiltration section of the Building Design.

*Input may be U-Factor or R-Value depending on user settings.