HomeMy WebLinkAboutFile Documents.COACH RD.0079.2018 (40).ARBKDEW POINT CALCULATION
JOB NAME: DBX 7
JOB NUMBER: 18003.00
DATE: 3/30/18
CALCS BY: JSW 5/8:12 Slope Roof
DP @ DP @ DP @ DP @ DP @
20% RH 25% RH 30% RH 35% RH 45% RH
30 33 37 41 48
0
Indoor design temperature (IDT)70
70
R-value
0.17
0.00
0.00
0.94
38.00
19.00
0.00
0.56
0.61
59.28
20.17
46
41
YES
Note: To minimize the potential for condensation problems,
humidity levels within the home must be properly controlled
and adjusted based on outdoor temperatures.
Roof Underlayment
3/4" plywood
Spray Foam Insulation
Outdoor design temperature (ODT)
Delta T = IDT - ODT
Layer
Thermal Resistance of Proposed Roof Assembly
Outside air layer
Roofing
A: point of condensation analysis
Vapor barrier
5/8" gypboard
TA = IDT - (R-value at A)/(R-Total) * (Delta T)
TA = Temperature at point A
Batt Insulation
Is TA warmer than the DPA?
Inside air layer
R-Total
R-value at A
DPA = Dew point at point A (35% RH)
3/30/18
4/5/2018
DEW POINT CALCULATION
JOB NAME: DBX 7
JOB NUMBER: 18003.00
DATE: 3/30/18
CALCS BY: JSW Flat Roof
DP @ DP @ DP @ DP @ DP @
20% RH 25% RH 30% RH 35% RH 45% RH
30 33 37 41 48
0
Indoor design temperature (IDT)70
70
R-value
0.17
0.00
0.00
0.94
10.00
38.00
19.00
0.00
0.56
0.61
69.28
20.17
50
41
YES
Note: To minimize the potential for condensation problems,
humidity levels within the home must be properly controlled
and adjusted based on outdoor temperatures.
DPA = Dew point at point A (35% RH)
Is TA warmer than the DPA?
Rigid Insulation
5/8" gypboard
Inside air layer
R-Total
R-value at A
TA = Temperature at point A
TA = IDT - (R-value at A)/(R-Total) * (Delta T)
Roof Underlayment
3/4" plywood
Spray Foam Insulation
A: point of condensation analysis
Batt Insulation
Vapor barrier
Outdoor design temperature (ODT)
Delta T = IDT - ODT
Thermal Resistance of Proposed Roof Assembly
Layer
Outside air layer
Roofing
3/30/18
4/5/2018