HomeMy WebLinkAboutFile Documents.287 McSkimming Rd.0044.2018 (13).ARBKDEW POINT CALCULATION
JOB NAME: 287 McSkimming
JOB NUMBER: 17009.00
DATE: 5/1/17
CALCS BY: JAH
TYPICAL ROOF
DP @ DP @ DP @ DP @ DP @
20% RH 25% RH 30% RH 35% RH 45% RH
30 33 37 41 48
5
Indoor design temperature (IDT)70
65
R-value
0.17
0.00
0.00
0.94
29.25
21.00
0.00
0.56
0.61
52.53
22.17
43
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.
5.5" batt insulation
Metal Roof Underlayment
3/4" plywood
4.5" spray foam insulation (R-6.5/in)
Outdoor design temperature (ODT)
Delta T = IDT - ODT
Layer
Thermal Resistance of Proposed Roof Assembly
Outside air layer
Metal Roofing
Is TA warmer than the DPA?
Inside air layer
R-Total
R-value at A
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
DPA = Dew point at point A (35% RH)
5/1/17
Received
5/02/2017 12:40:39 PM
DEW POINT CALCULATION
JOB NAME: 287 McSkimming
JOB NUMBER: 17009.00
DATE: 5/1/17
CALCS BY: JAH
LIVING ROOM ROOF
DP @ DP @ DP @ DP @ DP @
20% RH 25% RH 30% RH 35% RH 45% RH
30 33 37 41 48
-20
Indoor design temperature (IDT)70
90
R-value
0.17
0.00
0.00
0.94
48.75
0.00
0.00
0.56
0.61
51.03
1.17
68
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?
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)
Metal Roof Underlayment
3/4" plywood
7.5" spray foam insulation (R-6.5/in)
A: point of condensation analysis
0" batt insulation
Vapor barrier
Outdoor design temperature (ODT)
Delta T = IDT - ODT
Thermal Resistance of Proposed Roof Assembly
Layer
Outside air layer
Metal Roofing
5/1/17
Received
5/02/2017 12:40:39 PM