1、Designation: E241 09 (Reapproved 2014)1Standard Guide forLimiting Water-Induced Damage to Buildings1This standard is issued under the fixed designation E241; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEUnits statement was inserted in Section 1.5, units information was corrected, and editorial changes were madethroughout in May 2014.1. Sco
3、pe1.1 This guide covers building design, construction,commissioning, operation, and maintenance.1.2 This guide addresses the need for systematic evaluationof factors that can result in moisture-induced damage to abuilding or its components. Although of great potentialimportance, serviceability issue
4、s which are often, but notnecessarily, related to physical damage of the building or itscomponents (for example, indoor air quality or electricalsafety) are not directly addressed in this guide.1.3 The emphasis of this guide is on low-rise buildings.Portions of this guide; in particular Sections 5,
5、6, and 7; mayalso be applicable to high-rise buildings.1.4 This guide is not intended for direct use in codes andspecifications. It does not attempt to prescribe acceptable limitsof damage. Buildings intended for different uses may havedifferent service life expectancies, and expected service liveso
6、f different components within a given building often differ.Furthermore, some building owners may be satisfied withsubstantially shorter service life expectancies of buildingcomponents or of the entire building than other buildingowners. Lastly, the level of damage that renders a componentunservicea
7、ble may vary with the type of component, the degreeto which failure of the component is critical (for example,whether failure constitutes a life-safety hazard), and the judge-ment (that is, tolerance for damage) of the building owner. Forthe reasons stated in this paragraph, prescribing limits ofdam
8、age would require listing many pages of exceptions andqualifiers and is beyond the scope of this guide.1.5 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not co
9、nsidered standard.1.6 This standard does not purport to address the safetyconcerns associated with its use. It is the responsibility of theuser of this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2. Referenced D
10、ocuments2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationC717 Terminology of Building Seals and SealantsC755 Practice for Selection of Water Vapor Retarders forThermal InsulationC1193 Guide for Use of Joint SealantsD1079 Terminology Relating to Roofing and WaterproofingE331 Test Me
11、thod for Water Penetration of ExteriorWindows, Skylights, Doors, and Curtain Walls by Uni-form Static Air Pressure DifferenceE547 Test Method for Water Penetration of ExteriorWindows, Skylights, Doors, and Curtain Walls by CyclicStatic Air Pressure DifferenceE631 Terminology of Building Construction
12、sE632 Practice for Developing Accelerated Tests to AidPrediction of the Service Life of Building Componentsand MaterialsE1105 Test Method for Field Determination of Water Pen-etration of Installed Exterior Windows, Skylights, Doors,and Curtain Walls, by Uniform or Cyclic Static AirPressure Differenc
13、eE1643 Practice for Selection, Design, Installation, and In-spection of Water Vapor Retarders Used in Contact withEarth or Granular Fill Under Concrete SlabsE1677 Specification forAir Barrier (AB) Material or Systemfor Low-Rise Framed Building WallsE1745 Specification for Plastic Water Vapor Retarde
14、rs Usedin Contact with Soil or Granular Fill under Concrete SlabsE2112 Practice for Installation of Exterior Windows, Doorsand Skylights1This guide is under the jurisdiction of ASTM Committee E06 on Performanceof Buildings and is the direct responsibility of Subcommittee E06.41 on AirLeakage and Ven
15、tilation PerformanceCurrent edition approved April 1, 2014. Published May 2014. Originallyapproved in 1964. Last previous edition approved in 2009 as E241 09. DOI:10.1520/E0241-09R14E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceas
16、tm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E2136 Guide for Specifying and Evaluating Performance ofSingl
17、e Family Attached and Detached DwellingsDurability2.2 Other Documents:ASCE/SEI 2405 Flood Resistant Design andConstruction, American Society of Civil Engineers, Struc-tural Engineering Institute, Reston, VA.ASHRAE Handbook of Fundamentals Chapter 23: Ther-mal and Moisture Control in Insulated Assemb
18、liesFundamentals; Chapter 24: Thermal and Moisture Con-trol in Insulated AssembliesApplications; Chapter 27:Ventilation and Infiltration; Chapter 29: Residential Cool-ing and Heating Load Calculations; Chapter 30: Nonresi-dential Cooling and Heating Load Calculations; Ameri-can Society of Heating Re
19、frigerating, and AirConditioning Engineers; Atlanta, GA, 2005.ASHRAE Standard 62 Ventilation for Acceptable IndoorAir Quality3ASHRAE Technical Data Bulletin, Vol 10, No. 3 Recom-mended Practices for Controlling Moisture in CrawlSpaces, American Society of Heating, Refrigerating andAir Conditioning E
20、ngineers, Atlanta, GA, 1994.ASTM MNL 18 Trechsel, H., (ed.), Moisture Control inBuildings, American Society for Testing and Materials,West Conshohocken, PA, 1994.ASTM MNL 40 Trechsel, H., (ed.), Moisture Analysis andCondensation Control in Building Envelopes, AmericanSociety for Testing and Material
21、s, West Conshohocken,PA, 2001.Bateman, R., “Nail-On Windows” Installation (2) movement of watervapor by air movement; and (3) water vapor diffusion by vaporpressure differences. These transport mechanisms can delivermoisture into the building or the building envelope, in whichcases it is desirable t
22、hat they be controlled. These transportmechanisms can also act to remove moisture from the buildingor building envelope, in which cases they may be used topromote drying.5.3.1 In control of moisture delivery to the building orbuilding envelope, the transport mechanisms that have thepotential for mov
23、ing the greatest amounts of moisture should(where practical) be controlled first. In promotion of drying ofthe building or building envelope, the transport mechanismsE241 09 (2014)14that have the potential for moving the greatest amounts ofmoisture should (where practical) be utilized first.5.4 Buil
24、ding assemblies can become wet in three ways: (1)moisture can enter from the exterior, (2) moisture can enterfrom the interior, or (3) the assembly can start out wet as aresult of using wet building materials or building under wetconditions.5.4.1 Moisture typically enters building assemblies from th
25、eexterior through three mechanisms: (1) liquid flow by gravity,air pressure, surface tension, momentum, or capillary suction;(2) movement of water vapor by air movement; or (3) watervapor diffusion by vapor pressure differences.5.4.2 Moisture typically enters building assemblies from theinterior thr
26、ough two mechanisms: (1) movement of watervapor by air movement, or (2) water vapor diffusion by vaporpressure differences.5.4.3 Operation of mechanical equipment has not alwaysbeen recognized for its potential influence on moisture transfer.This potential influence should not be overlooked. Mostnot
27、ably, air handling equipment can induce a moisture trans-port mechanism that is capable of moving large amounts ofmoisture, namely movement of water vapor by air movement.Unplanned pressurization or depressurization of buildings orportions of buildings by air handlers can result in substantialmoistu
28、re accumulations in the building envelope.5.5 Moisture can typically be removed (dried) to the exte-rior or the interior by three mechanisms: (1) liquid flow bygravity (drainage) or capillary suction, (2) movement of watervapor by air movement (ventilation), or (3) water vapordiffusion by vapor pres
29、sure differences.5.5.1 Where condensation of water vapor or water leaks canoccur, weep paths to drain liquid water to a place where it canbe dissipated are often effective. Converting liquid water tovapor, and dissipating the vapor by air movement may also bepractical.6. Limit States6.1 Identificati
30、on of conditions that must be avoided inorder to prevent degradation of building components is animportant step in making design or operating decisions.However, precise guidelines for identification of such condi-tions are generally lacking. Rather rough estimates based onempirical experience are of
31、ten used.6.2 Time and temperature are factors that are interrelatedwith moisture level in the degradation of building components.The moisture/temperature/time combinations that result inmaterial degradation furthermore vary with the type of mate-rial. For example, wood will not decay, even at elevat
32、edmoisture content when its temperature is near or belowfreezing, and even at temperature conditions conducive todecay, wood can withstand intermittent wettings of shortduration to elevated moisture contents without decay becomingestablished. Conversely, masonry units can generally be ex-pected to w
33、ithstand elevated moisture conditions at tempera-tures above freezing for extended time periods (conditionsunder which wood decay might be expected), but sufferdamage if frozen in a saturated condition.6.2.1 Many materials or constructions have threshold watercontents below which deterioration may b
34、e slow enough to benegligible for designed life expectancy. As indicated in 6.1these threshold values are often rather rough estimates. See“Humidity and Building Materials” (Connolly, 1993) forestimates.6.2.2 The concepts of critical moisture content and criticalcumulative exposure time (see 3.5.4)
35、are discussed in Chapter26 of ASTM MNL 18. Although these concepts are generallyrecognized by building scientists, organized use of these aslimit states by designers has not yet become a well-recognizedpractice.6.3 Alimit state is frequently based on avoidance of damageto a component as the result o
36、f its getting wet.Alimit state mayalso be based on avoidance of damage to a component as aresult of moisture conditions in an adjacent component. Forexample, limiting moisture-induced dimensional change ofplywood sheathing may be critical to prevent cracking ofstucco cladding.7. Design Evaluation To
37、ols7.1 Means for evaluating the design of building envelopesfrom the perspective of moisture management can be classifiedas follows: (1) conceptual, (2) mathematical using computersimulation models, and (3) mathematical using calculationsthat can be performed without computer software (sometimesrefe
38、rred to as manual design tools).7.1.1 Conceptual Design EvaluationThis approach in-volves the following three-step procedure: (1) determine prob-able external and internal environmental loads (determineclimate and interior design conditions), (2) determine thepotential moisture transport mechanisms
39、in each assembly, and(3) select moisture control strategies. This approach provides aqualitative perception of how a building will perform under theinfluence of all the moisture loads the building is likely to besubjected to. The Moisture Control Handbook (Lstiburek andCarmody, 1991) provides a more
40、 comprehensive treatment ofthis approach. Conceptual design evaluation can be used toselect a construction for a given climate, as well as to evaluatehow a proposed construction may perform in a given climate.7.1.2 Computer Hygrothermal Analysis SimulationModelsThese models have been developed to qu
41、antitativelypredict moisture and temperature conditions within proposedassemblies using boundary conditions representative for theclimate and interior design conditions. As stated in Chapter 6of ASTM MNL 40, the more detailed computer simulationmodels employ finite-element or finite-difference schem
42、es.These models mathematically model moisture and heat transfermechanisms at the inner and outer surfaces of the assembliesand within the assemblies. Some of the models predict mois-ture transfer by air movement and liquid water flow as well asby vapor diffusion. Use of such models requires knowledg
43、e ofbuilding physics and of the limitations of the model used. Mostmodels allow estimates of the duration of a set of temperatureand moisture conditions within assemblies. A discussion ofavailable models is found in Chapter 2 of ASTM MNL 18, inChapter 6 of ASTM MNL 40, and in Chapter 23 of theASHRAE
44、 Handbook of Fundamentals.E241 09 (2014)157.1.3 Manual Design ToolsThese are termed “simplifiedhygrothermal analysis method models” in Chapter 6 ofASTM MNL 40 and “simplified hygrothermal design calcula-tions and analyses” in Chapter 23 of the ASHRAE Hand-book of Fundamentalss. Manual design tools,
45、like computersimulation models, provide quantitative estimates of moistureconditions within building envelopes. They only accounthowever for moisture transfer by vapor diffusion. Their focusis on predicting the occurrence of sustained condensationwithin building assemblies. The calculations for manu
46、al designtools can be easily performed with a handheld calculator or ina computer spreadsheet. The traditional design tool used inNorth America is a manual design tool and is referred to as thedewpoint method. An example of the dewpoint method isoutlined in Appendix X1.1 of Practice C755. The validi
47、ty andusefulness of predictions made with manual design tools havelimitations. Most notably, manual design tools do not provideestimates of the time period during which potentially damagingconditions may occur. Despite the limitations of manual designtools, some relatively unsophisticated analysis p
48、rocedures, likedewpoint analysis, can be useful for rapidly comparing relativeperformances of many different proposed constructions. Adiscussion of manual design tools is found in Chapter 11 ofASTM MNL 18 and in Chapter 23 of the ASHRAE Hand-book of Fundamentals.8. Examples of Practices that Enhance
49、 Durability8.1 Drainage of Precipitation and Surface Runoff:8.1.1 Surface GradingGround should slope away fromwalls so that precipitation runoff from land areas does not pondnear the foundation.8.1.2 Building External DrainsDischarge from drains atground level should be carried away from the foundation, andshould flow away from it.8.1.3 Below-Grade Drainage SystemsIn some casesbelow-grade drainage systems may be required. In some cases,dissipation of collected water by pumping will be required.Below grade drainage systems are discussed in Chapter 2 ofThe Moisture Co
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