1、Designation: C 1496 01Standard Guide forAssessment and Maintenance of Exterior Dimension StoneMasonry Walls and Facades1This standard is issued under the fixed designation C 1496; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide outlines how to visually assess exterior stonemasonry walls and facades to determine their genera
3、l condi-tion. Examining key features of the construction can helpidentify and diagnose problems which require repairs orcorrective action. Such an examination can expose conditionswhich may be addressed with maintenance and minor repairs,or may require expert assistance. This guide is not intended t
4、obe used for buildings requiring major exterior rehabilitation orstructural repairs.1.1.1 This guide applies to walls of solid stone or dimensionstone used as a cladding. Stone cladding is typically connectedto a backup material with a variety of anchoring methods,including traditional hand-set maso
5、nry anchors such as straps,dowels, cramps, hook-and-eyes, dove-tails, wire ties, and thelike. Joints between stones in these types of buildings areusually filled with mortar or sealant. Sealant-filled joints areusually designed to accommodate structural and thermal move-ments.1.2 This guide specific
6、ally excludes dimension stone used ininterior building surfaces, flooring or paving, slate dimensionstone used as roofing. Though they share some similar assess-ment and maintenance concerns, thin stone (less than 2 inchesnominal thickness) exterior cladding, and stone cladding at-tached to metal fl
7、ames are also excluded due to their uniquedesign characteristics and performance requirements. Althoughprocedures and cautions listed herein may apply to walls andfacades containing semi-dimension, or partially sized, stone inthe form of split-face, or rubble and to stone-facade concretepanels, the
8、guide is not specifically directed to such stone use.It does not address removal of small-area stains.2. Referenced Documents2.1 ASTM Standards:C 119 Terminology Relating to Dimension Stone23. Terminology3.1 Terms used in this guide are defined in TerminologyC 119.3.2 Definitions of Terms Specific t
9、o This Standard:3.2.1 crack monitorany of the several two-part devicesthat can be attached to stone masonry in such a way that theycan span cracks in order to periodically measure changes incrack width thereby indicating movement.3.2.2 dutchmanrepair used to patch stone masonry with asection of new
10、stone. The damaged area within a particularstone element is removed. The remaining void is trimmed to aregular shape. A new piece of stone, or “dutchman,” is cut frommatching stone cut slightly smaller than the area to be filled. Itis installed using dowels or some other mechanical attachment,then a
11、dhered, or mortared into place.3.2.3 exfoliationdeterioration or loss of stone in the formof flakes, scales, and layers.3.2.4 professional assistanceindependent opinions andrecommendations provided by persons having expertise in theassessment and repair of stone masonry. Such professionalsmay includ
12、e independent consultants such as architects, engi-neers, material scientists such as mineralogist or geologists, orstone masonry contractors.3.2.5 thickstones with a nominal bed-depth of 2 in. (5cm.) or more.4. Significance and Use4.1 This guide attempts to provide information to assistbuilding own
13、ers and managers with limited knowledge of stoneconstruction to recognize basic problems with performance offacades, and to keep them in good condition through periodicinspections and maintenance. Increased awareness of thebehavior of stone masonry facades and associated materialscan reduce maintena
14、nce and replacement costs by addressingproblems and deterioration early.4.2 The objective of all maintenance should be to limitdeterioration through early intervention. When it appearsdamage to stone support elements has occurred, professionalsshould be consulted to evaluate the support conditions,
15、as well1This guide is under the jurisdiction of ASTM Committee C18 on DimensionStone and is the direct responsibility of Subcommittee C18.07 on EnvironmentalProperties, Behavior and Cleaning.Current edition approved April 10, 2001. Published July 2001.2Annual Book of ASTM Standards, Vol 04.07.1Copyr
16、ight ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.as recommend methods to restore the buildings integrity andpreserve public safety.5. Introduction5.1 An effective maintenance program for exterior stonemasonry should incorporate preventive m
17、aintenance among itskey elements. Early attention to problems, and simple mea-sures to remedy them, will often avoid costly renovation later.This guide is intended to help interested personnel locate suchproblem areas, better understand potential causes of stonedeterioration, and identify appropriat
18、e corrective measures forthe observed deficiencies.5.2 Maintenance supervisors should understand how theirbuilding is constructed to apply this guide and better maintaintheir buildings. Employing a professional to assist them ininterpreting pertinent drawings and documents, and initiallyinspecting c
19、onditions should help them become effectiveobservers of stone performance.5.3 This guide lists many typical problems that can affectstone masonry, facades. It describes likely causes, and dis-cusses common repair methods. All initial attempts at repairsshould be done under the observation of a profe
20、ssional toensure the use of proper materials and techniques.5.4 Personnel responsible for stone facade maintenanceshould be familiar with the systems used in the construction oftheir buildings on at least an elementary level. Prior toinspections, they should be briefed by personnel knowledge-able ab
21、out the building and its construction, particularly thestone wall system. This background should help in determiningwhen the engagement of a professional should be considered.6. Guidelines for Inspections6.1 Schedule InspectionsSchedule and perform semi-annual inspections of stone wall elements. Ins
22、pect all eleva-tions of the building. A walk-around visual survey with acamera and binoculars should be a minimum procedure. Useadjacent buildings roofs and windows to gain same-levelaccess, to examine building facades and associated elements.Use building windows and set-backs where possible foraddi
23、tional vantage points. If the available access is not suffi-cient to perform the inspections, then consider methods, asoutlined in 6.3. Photograph any observed distress or problemareas for later reference in determining appropriate repairs.6.2 Condition Documentation/MonitoringKeep accurateand cumul
24、ative records of inspection findings. Buildings con-structed of thick dimension stone with mortar or sealant-filledjoints react slowly to environmental forces. Knowledge of thetiming of a conditions onset and understanding its progress aidin assessing the distressed condition. Monitor critical ordet
25、eriorated areas between scheduled inspections. Use mea-surements or crack monitors to measure changes in cracks,increasing lippage between stones (stones projecting or retreat-ing in plane from the adjacent stones), or other changes anddisplacements in stone position. Well-kept records will aid inth
26、e diagnosis of the specific causes of the conditions observed,should more experienced professionals be required.6.3 Tall BuildingsInspections of buildings with heightsthat exceed those readily observable with binoculars, or withlimited vantage points require more detailed planning. It willbe necessa
27、ry to view representative areas of the facades fromsuspended or fixed scaffolding, mobile work platforms, orpersonnel lifts to adequately observe existing conditions.7. Procedure for Evaluation of Stone Conditions7.1 At a minimum, the following procedure should be usedas a guide to decide an appropr
28、iate course of action forobserved deficiencies as part of an inspection and maintenanceprogram for stone masonry facades.7.1.1 Identify and document the defects.7.1.2 Note the extent of the defects, patterns or concentra-tions of distress.7.1.3 Postulate the likely causes.7.1.4 Perform necessary mai
29、ntenance or obtain assistancewith repairs:7.1.4.1 If the condition is stable and does not appear to beprogressive, perform appropriate maintenance, and simple ortemporary repairs.7.1.4.2 If the cause is not apparent, and the conditionappears stable and not progressive, monitor the condition andconsu
30、lt with professionals to determine the cause and appro-priate repairs.7.1.4.3 If the observed conditions are considered dangerousor progressive, obtain professional assistance immediately.8. Maintenance8.1 Routine MaintenanceMany problems can begin orworsen due to neglect of routine maintenance. Sto
31、ne masonryitself, when used in an exterior application, requires periodicjoint repairs, such as sealant replacement, tuck pointing, andcleaning. Stone facade components can also be affected by alack of maintenance of other building systems, such as roofs,parapets, windows, and flashing.8.2 CleaningR
32、egular cleaning is also critical to the longterm durability of natural stone facades, as well as theirappearance. Cleaning methods should be selected that do notdamage the stone. Cleaning methods and materials should befirst tested, from the least to the most aggressive, to determinethe mildest trea
33、tment that provides satisfactory results. Prior toimplementing a cleaning technique building-wide, test areasshould be cleaned using the proposed methods. The areasshould be evaluated for a minimum period of six weeks toassess the results. Improper selection of cleaning chemicalsand procedures will
34、produce unsightly and irreversible damageto the appearance, and potentially the structural integrity, of thestone facade components.9. Areas of Focus for Inspection9.1 Moisture or Water StainingLook for signs of moistureentrance on interior and exterior surfaces, as well as throughoutthe stone wall
35、system. Water penetration can lead not only todeterioration of interior finishes, but also to stone and jointmaterial degradation and corrosion of anchor system compo-nents if the water is trapped behind or within the wall or facadesystem for prolonged periods. Water absorbed into stone andjoint mat
36、erials can cause dimensional changes, potentiallyreducing clearances and creating stress concentrations.Trapped water can freeze and expand, causing the stone toC1496012weaken, and eventually spall or crack. Joint materials may alsodeteriorate as a result.9.1.1 Water can also carry minerals, chemica
37、ls, or othercontaminants that can be deposited on or within the stone andjoints, causing discoloration, staining, or deterioration.9.1.2 Wetness, staining, or darkening may be due to trappedmoisture. Discoloration or deposition of efflorescence (a pow-dery white or gray accretion on stone faces) may
38、 also beevidence of moisture entry, or “rising damp.” Rising damp is acondition in which the stones appear darker due to waterwicking into the stone by capillary action from a water sourcealong one or more edges of the stone, such as at the base of abuilding.9.2 JointsEvery inspection should include
39、 a review ofeach joint between stones. Document anomalous and suspectconditions photographically, especially in areas of accelerateddeterioration. Where a problem is suspected, it is useful tocompare photographs taken at various times to establish theprogression and rate of deterioration.9.2.1 Look
40、for missing mortar and sealant, for cracks inmortar, for partings between mortar or sealant and the stone,for non-uniform joint sizes due to tight, closed or openingjoints, and for lipped stones. Connections between stones andnon-stone materials such as windows and other openings areoften particular
41、ly susceptible to racking and eccentric move-ment. Check for plugged weep holes throughout the wallsystem. Compare the width of expansion, control, and con-struction joints. Look for wider or narrower tops and bottomsof such joints.9.3 StoneCracks and spalled areas at or near joints mayindicate exce
42、ssive compression loading, anchor failure, andenvironmental deterioration, among other things. Misalign-ment of stone across a series of joints may indicate local orstructural building movements.9.3.1 Surface deterioration may take the form of exfoliation(where the surface is lost in thin layers), s
43、palling, powdering,or chipping. These conditions can be particularly prevalentwhere chloride-based de-icing products used on paving sys-tems aggravate the effects of freeze-thaw cycling Both calciumchloride (CaCl2) and sodium chloride (NaCl) are commonlyused. Both will cause damage to stone surfaces
44、.9.4 FacadesSight along walls for bulging areas, particu-larly in those containing smaller stones. Look for areas ofdifferent, or changing, colors. Compare colors before and afterrains; a continuing damp appearance for some time after a rainmay suggest a leak. Cracks across stones, or diagonally alo
45、ngmortar joints, may suggest unaccommodated expansion andcontraction or structural movements.9.5 Unique Details and Fenestration of the BuildingLookparticularly at parapets, copings, building returns and corners,and projecting or corbeled courses, for dampness and misalign-ment. Check all facades at
46、 their bases for the appearance ofrising damp. Compare the appearance of joints and stones atand near openings. Due to the typical uniqueness of theirinstallation, soffit stones deserve special attention to theiralignment, color retention, and joint conditions.9.6 Building Components Not Fabricated
47、from StoneMany problems on buildings occur in the roof/parapet areas,near openings, and at grade. Look carefully at the insidesurfaces of parapets; check the flashing and counter-flashing;the cant-strip and blocking; the mortar of masonry, back-up orunder the coping; the coping head joints; expansio
48、n joints; andthe roof membrane. Inspect roof valleys, particularly at theirends, where they terminate into drams and down spouts. Checkfor functioning dram leaders and down spouts. Also note anycracks and open joints at and near windows and doors.10. Common Problems and Typically RecommendedRepairs1
49、0.1 The following section lists a number of commonproblems that can occur with exterior stone wall constructionwhich can be identified and addressed, at least in early stages,by a maintenance staff with some specific training. Theconditions are listed from least to most serious. Table 1 is abrief summary of common stone problems, their repairs, andthe consequences of delaying corrective action. However,complex distressed conditions and advanced stages of anystone masonry problem may need the attention of experiencedprofessionals.10.1.1 Rising DampStone masonry at or ex
