HomeMy WebLinkAboutDew Point Calculation 10.14.2020DEW POINT CALCULATION
JOB NAME: 5354 Rimledge Rd
JOB NUMBER: 5079.00
DATE: 10/14/20
CALCS BY: CGC
ADER:
ENGINEERING • COMFORT SYSTEMSM
DP @
20% RH
DP @
25% RH
DP @
30% RH
DP @
35% RH
DP @
45% RH
30
33
37
41
48
Outdoor design temperature (ODT)
-10
Indoor design temperature (IDT)
70
Delta T = IDT - ODT
80
Thermal Resistance of Proposed Roof Assembly
Layer
R -value
Outside air layer
0.17
Metal Roofing
0.00
Metal Roof Underlayment (3/4" Plywood)
0.93
6" Rigid Spray Foam Insulation (R-6.7/inch)
40.20
A: point of condensation analysis
6" Batt Insulation (R-19)
19.00
Vapor barrier
0.00
1/2" gypboard
0.50
Inside air layer
0.61
R -Total
61.41
R -value at A
20.11
TA = Temperature at point A
TA = IDT - (R -value at A)/(R-Total) * (Delta T)
44
DPA = Dew point at point A (35% RH)
37
Is TA warmer than the DPA?
YES
Note: To minimize the potential for condensation problems,
humidity levels within the home must be properly controlled
and adjusted based on outdoor temperatures.