Skip to Main Content
Skip Nav Destination
ASTM Selected Technical Papers
Roofing Research and Standards Development: 10th Volume
Editor
Sudhakar Molleti
Sudhakar Molleti
Symposium Chair and STP Editor
1
National Research Council Canada
,
Ottawa, ON,
CA
Search for other works by this author on:
Walter J. Rossiter, Jr. Jr.
Walter J. Rossiter, Jr. Jr.
Symposium Chair and STP Editor
2
W.J. Rossiter & Associates
,
Clarksburg, MD,
US
Search for other works by this author on:
ISBN:
978-0-8031-7747-5
No. of Pages:
254
Publisher:
ASTM International
Publication date:
2023

High humidity and corrosive indoor environments in natatoriums in cold climates pose unique risks and challenges due to moisture condensation in roofs. Without the existence of standards for roof design, based on a simple, steady-state dew-point analysis, the common practice is to employ at least a 0.1 perm vapor retarder on the warm side of the assembly to eliminate the risk of condensation. The use of the vapor retarder in preventing condensation is not well understood. This study investigates the role of a vapor retarder in a roof assembly for natatoriums by hygrothermal modeling in Climate Zone 7 using WUFI. A wood composite roof deck (R-value of > 35 hr·ft2·°F/BTU) that provides acoustics, thermal insulation, and a nailable surface such as oriented stranded board (OSB), with and without a vapor retarder, at different locations in the assembly is used as a roofing candidate for the simulation. The moisture accumulation in the OSB board over the years of exposure is used as an indicator of the roof's performance. In addition, the presence of a dew point to verify the occurrence of condensation in the assembly is monitored. The simulation results show that even without a vapor retarder: 1) The moisture content in the OSB reaches a dynamic steady state in 3-5 years. 2) Maximum moisture content in the OSB does not exceed more than 11.6% (>20% is considered “risky”). 3) There is no risk of condensation in the assembly at any point in time. 4) With the placement of a vapor retarder on the warm side or close to the OSB, the maximum moisture content is reduced to 11.2%. These observations contradict the simple dew point analysis model that is commonly used to prescribe a vapor retarder for the roof assembly and question the need for one in the roof assemblies.

1.
Lochner
G.
and
Wasner
L.
, “
Ventilation Requirements for Indoor Pools
,”
ASHRAE Journal
59
, no.
7
(July
2017
): 16–24.
2.
American National Standard Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools
,
ASA/ANSI S12.60-2019, Part 4: “Acoustic Standards for Physical Education Teaching”
(
Melville, NY
:
Acoustical Society of America
,
2019
).
3.
American Society of Heating, Refrigerating and Air-Conditioning Engineers
,
2021 ASHRAE Handbook—Fundamentals
, Chapter 25 (
Peachtree Corners, GA
:
ASHRAE Publications
,
2021
).
4.
TenWolde
A.
and
Bomberg
M. T.
, “
Design Tools
,” in
Moisture Control in Buildings: The Key Factor in Mold Prevention—2nd Edition
, ed.
Trechsel
H. R.
and
Bomberg
M.
(
West Conshohocken, PA
:
ASTM International
,
2009
), 128–138,
5.
American Society of Heating, Refrigerating and Air-Conditioning Engineers
,
Criteria for Moisture-Control Design Analysis in Buildings
, ANSI/ASHRAE Standard 160-2016 (
Atlanta, GA
:
ASHRAE
,
2016
).
6.
Kumaran
M. K.
, “
A Thermal and Moisture Property Database for Common Building and Insulation Materials
,”
ASHRAE Transactions
112
, no.
2
(
2006
): 485–497.
7.
Desjarlais
A.
,
Pierce
H. H.
, and
Pallin
S.
, “
Using Hygrothermal Modeling to Resolve Practical Low-Slope Roofing Issues
,” in
Advances in Hygrothermal Performance of Building Envelopes: Materials, Systems and Simulations
, ed.
Mukhopadhyaya
P.
and
Fisler
D.
(
West Conshohocken, PA
:
ASTM International
,
2017
), 291–302,
8.
Mundt-Peterson
S. O.
and
Harderup
L.
, “
Validation of a One-Dimensional Transient Heat and Moisture Calculation Tool under Real Conditions
,” Paper No. 104 in
Thermal Performance of the Exterior Envelopes of Whole Buildings XII International Conference
(
Oak Ridge, TN
:
Oak Ridge National Laboratory
,
2013
).
9.
Bludau
C.
,
Zirkelbach
D.
, and
Kunzel
M. H.
, “
Condensation Problems in Cool Roofs
,”
IIBEC Interface
27
, no.
7
(
2009
): 11–16.
10.
Kehrer
M.
and
Pallin
S.
, “
Condensation Risk of Mechanically Attached Roof Systems in Cold Climate Zones
” (paper presentation, Twenty-Eighth RCI International Convention and Trade Show,
Orlando, FL
, March 14–19,
2013
).
11.
Desjarlais
A.
, “
Self Drying Roofs: What! No Dripping!
,” in
Proceedings of the Thermal Performance of the Exterior Envelopes of Buildings, VI Conference
(
Oak Ridge, TN
:
Oak Ridge National Laboratory
,
1995
), 763–773.
12.
Bludau
C.
,
Kunzel
H. M.
, and
Zirkelbach
D.
, “
Hygrothermal Performance of Flat Roofs with Construction Moisture
,” Paper 44 in
Thermal Performance of the Exterior Envelopes of Whole Buildings, Eleventh International Conference
(
Oak Ridge, TN
:
Oak Ridge National Laboratory
,
2010
).
This content is only available via PDF.
You do not currently have access to this chapter.
Close Modal

or Create an Account

Close Modal
Close Modal