HomeMy WebLinkAboutFile Documents.210 S West End St.0020-2020-BCHO (10)DEW POINT CALCULATION
JOB NAME: Sack Renovation
JOB NUMBER: 19005.00
DATE: 2/28/2020
CALCS BY: JSW Existing Roof - New Insulation
DP @ DP @ DP @ DP @ DP @
20% RH 25% RH 30% RH 35% RH 45% RH
30 33 37 41 48
-15
Indoor design temperature (IDT) 70
85
R-value
0.17
0.81
0.94
38.00
11.00
0.56
0.61
52.09
12.17
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.
TA = IDT - (R-value at A)/(R-Total) * (Delta T)
DPA = Dew point at point A (35% RH)
Is TA warmer than the DPA?
3/4" plywood
R-38 Spray Foam
A: point of condensation analysis
5/8" gypboard
Inside air layer
R-11 batt insulation
R-Total
R-value at A
TA = Temperature at point A
Outdoor design temperature (ODT)
Delta T = IDT - ODT
Thermal Resistance of Proposed Roof Assembly
Layer
Outside air layer
Roofing
2/28/20
Drew Rader
03/09/2020
04/30/2020
justinh