ASTM C1496-18

Standard Guide for Assessment and Maintenance of Exterior Dimension Stone Masonry Walls and Facades

ABSTRACT
This guide outlines the standard procedures for the visual assessment and maintenance of exterior dimension stone masonry walls and facades to determine their general condition. The examination procedures established here can help identify and diagnose problems that require repairs or corrective action, but is not intended to be used for buildings requiring major exterior rehabilitation or structural repairs. This guide applies to walls of solid stone or dimension stone claddings with joints usually filled with mortar or sealant that are designed to accommodate structural and thermal movements. This guide specifically excludes the following: dimension stone used in interior building surfaces, flooring, or paving; slate dimension stone used as roofing; thin stone exterior cladding; stone cladding attached to metal flames; the removal of small area stains. Also, this guide may apply, but is not specifically directed, to the following: walls and facades containing semi-dimensions, or partially sized, stone in the form of split-face or rubble; and stone-facade concrete panels. The common problems to consider include rising damps; mortar distresses; surface losses; cracks; displacements, bowings, or bulges; and spalls and fragments. The corresponding repairs to be made that shall address these problems are detailed for each.
SIGNIFICANCE AND USE
4.1 This guide attempts to provide information to assist building owners and managers with limited knowledge of stone construction to recognize basic problems with performance of facades, and to keep them in good condition through periodic inspections and maintenance. Increased awareness of the behavior of stone masonry facades and associated materials can reduce maintenance and replacement costs by addressing problems and deterioration early.  
4.2 The objective of all maintenance should be to limit deterioration through early intervention.  
4.3 When it appears damage to stone support elements has occurred, a qualified stone consultant should be employed to evaluate the support conditions, as well as recommend methods to restore the building's integrity and preserve public safety.
SCOPE
1.1 This guide outlines how to visually assess exterior stone masonry walls and facades to determine their general condition. Examining key features of the construction can help identify and diagnose problems which require repairs or corrective action. Such an examination can expose conditions which may be addressed with maintenance and minor repairs, or may require expert assistance. This guide is not intended to be used for buildings requiring major exterior rehabilitation or structural repairs.  
1.1.1 This guide applies to walls of solid stone or dimension stone used as a cladding. Stone cladding is typically connected to a backup material with a variety of anchoring methods, including traditional hand-set masonry anchors such as straps, dowels, cramps, hook-and-eyes, dove-tails, wire ties, and the like. Joints between stones in these types of buildings are usually filled with mortar or sealant. Sealant-filled joints are usually designed to accommodate structural and thermal movements.  
1.2 This guide specifically excludes dimension stone used in interior building surfaces, flooring or paving, slate dimension stone used as roofing. Though they share some similar assessment and maintenance concerns, thin stone (less than 2 in. nominal thickness) exterior cladding, and stone cladding attached to metal flames are also excluded due to their unique design characteristics and performance requirements. Although procedures and cautions listed herein may apply to walls and facades containing semi-dimension, or partially sized, stone in the form of split-face, or rubble and to stone-facade concrete panels, the guide is not specifically directed to such stone use. It does not address removal of small-area stains.  
1.3 This guide offers an organized collection of information or a...

General Information

• Status: Published
• Publication Date: 31-Oct-2018
• ICS: 91.060.10 - Walls. Partitions. Facades
• Technical Committee: C18 - Dimension Stone
• Drafting Committee: C18.07 - Environmental Properties, Behavior, and Cleaning

Relations

• Replaces: ASTM C1496-11 - Standard Guide for Assessment and Maintenance of Exterior Dimension Stone Masonry Walls and Facades
• Effective Date: 01-Nov-2018
• Refers: ASTM C119-19 - Standard Terminology Relating to Dimension Stone
• Effective Date: 01-May-2019
• Refers: ASTM E1971-19 - Standard Guide for Stewardship for the Cleaning of Commercial and Institutional Buildings
• Effective Date: 15-Apr-2019
• Refers: ASTM C119-16 - Standard Terminology Relating to Dimension Stone
• Effective Date: 01-May-2016
• Refers: ASTM C119-14e1 - Standard Terminology Relating to Dimension Stone
• Effective Date: 01-Dec-2014
• Refers: ASTM C119-14 - Standard Terminology Relating to Dimension Stone
• Effective Date: 01-Dec-2014
• Refers: ASTM C1515-13 - Standard Guide for Cleaning of Exterior Dimension Stone, Vertical And Horizontal Surfaces, New or Existing
• Effective Date: 15-Oct-2013
• Refers: ASTM E1971-05(2011) - Standard Guide for Stewardship for the Cleaning of Commercial and Institutional Buildings
• Effective Date: 15-Oct-2011
• Refers: ASTM C1515-11 - Standard Guide for Cleaning of Exterior Dimension Stone, Vertical And Horizontal Surfaces, New or Existing
• Effective Date: 01-Oct-2011
• Refers: ASTM C119-11 - Standard Terminology Relating to Dimension Stone
• Effective Date: 15-Jun-2011
• Refers: ASTM C1515-09 - Standard Guide for Cleaning of Exterior Dimension Stone, Vertical And Horizontal Surfaces, New or Existing
• Effective Date: 15-Sep-2009
• Refers: ASTM C119-08e2 - Standard Terminology Relating to Dimension Stone
• Effective Date: 01-Feb-2008
• Refers: ASTM C119-08e1 - Standard Terminology Relating to Dimension Stone
• Effective Date: 01-Feb-2008
• Refers: ASTM C119-08e3 - Standard Terminology Relating to Dimension Stone
• Effective Date: 01-Feb-2008
• Refers: ASTM C119-08 - Standard Terminology Relating to Dimension Stone
• Effective Date: 01-Feb-2008

Overview

ASTM C1496-18 provides a comprehensive guide for the assessment and maintenance of exterior dimension stone masonry walls and facades. Issued by ASTM International, this standard outlines best practices for visual inspection and routine maintenance to identify and address common issues in stone masonry facades before they require major repairs or structural intervention. The guide is intended to assist building owners, facility managers, and maintenance personnel with limited stone construction experience to preserve the longevity and appearance of exterior stone features, minimizing costly replacements and ensuring public safety.

Key Topics

• Visual Assessment Procedures
  The standard details practical methods for visually inspecting solid stone or dimension stone cladding systems mounted with traditional anchors (e.g., straps, dowels, wire ties). Inspection focuses on identifying cracks, spalls, bulges, surface deterioration, mortar or sealant distress, and signs of water ingress such as rising damp or efflorescence.

• Routine and Preventative Maintenance
  Emphasis is placed on periodic inspections (at least semi-annually), with guidelines for documenting conditions, monitoring changes (such as crack widths), and maintaining accurate records for diagnosis and maintenance planning.

• Common Problems and Solutions
  Typical defects addressed include:

  • Mortar joint cracking and deterioration
  • Compressed or failing joint sealant
  • Surface loss through powdering, exfoliation, or spalling
  • Stone displacement, bowing, or bulging
  • Water-related issues like rising damp or continuous wetness at grade
  • Fragmented or cracked stones requiring patching or replacement

  For each issue, the guide proposes repair and maintenance methodologies, such as tuck pointing, patching, resealing, cleaning, and in cases of advanced distress, consulting a qualified stone specialist for professional evaluation.

• Documentation and Monitoring
  The guide provides practical advice on keeping detailed records, using photographic evidence, and applying crack monitors or measurement tools to gauge deterioration over time.

Applications

ASTM C1496-18 applies to the following scenarios:

• Historic and Modern Buildings
  Suitable for both new and historic structures with exterior stone facades, where preservation of material integrity and aesthetics is a priority.

• Commercial, Institutional, and Residential Buildings
  Used across diverse property types to manage maintenance of stone envelope systems.

• Facility and Property Management
  Offers actionable steps for building owners, maintenance supervisors, and facility managers to identify issues early and ensure timely minor repairs.

• Preventive Maintenance Programs
  Essential for establishing regular inspection cycles, tracking facade performance, and making informed decisions about when to involve professional consultants.

Note: The standard does not cover major exterior rehabilitation, structural repairs, interior stone, stone used as roofing, thin stone cladding, or small-area stain removal.

Related Standards

For additional guidance and terminology related to stone masonry and facade maintenance, consider these ASTM standards:

• ASTM C119: Terminology Relating to Dimension Stone
• ASTM C1515: Guide for Cleaning of Exterior Dimension Stone, Vertical and Horizontal Surfaces, New or Existing
• ASTM E1971: Guide for Stewardship for the Cleaning of Commercial and Institutional Buildings

Key Benefits

• Provides structured methodologies for early detection of deterioration in natural stone facades.
• Helps building owners and managers reduce long-term maintenance costs.
• Offers a practical, stepwise approach to facade inspections and documentation.
• Supports sustainability and extends the life of exterior stonework through appropriate care and repair.

For preserving the beauty and structural integrity of exterior stone masonry, ASTM C1496-18 serves as an essential resource for developing and implementing effective inspection and maintenance programs.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1496 − 18
Standard Guide for
Assessment and Maintenance of Exterior Dimension Stone
Masonry Walls and Facades
This standard is issued under the fixed designation C1496; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope stone restoration design consultants. Not all aspects of this
guide may be applicable in all circumstances. This ASTM
1.1 This guide outlines how to visually assess exterior stone
standard is not intended to represent or replace the standard of
masonry walls and facades to determine their general condi-
care by which the adequacy of a given stone consultants
tion. Examining key features of the construction can help
service must be judged, nor should this document be applied
identify and diagnose problems which require repairs or
without consideration of a project’s many unique aspects. The
corrective action. Such an examination can expose conditions
word “Standard” in the title of this document means only that
which may be addressed with maintenance and minor repairs,
the document has been approved through theASTM consensus
or may require expert assistance. This guide is not intended to
process.
be used for buildings requiring major exterior rehabilitation or
structural repairs. 1.4 The values stated in inch-pound units are to be regarded
1.1.1 This guide applies to walls of solid stone or dimension as standard. The values given in parentheses are mathematical
stone used as a cladding. Stone cladding is typically connected conversions to SI units that are provided for information only
to a backup material with a variety of anchoring methods, and are not considered standard.
including traditional hand-set masonry anchors such as straps,
1.5 This standard does not purport to address all of the
dowels, cramps, hook-and-eyes, dove-tails, wire ties, and the
safety concerns, if any, associated with its use. It is the
like. Joints between stones in these types of buildings are
responsibility of the user of this standard to establish appro-
usually filled with mortar or sealant. Sealant-filled joints are
priate safety, health, and environmental practices and deter-
usuallydesignedtoaccommodatestructuralandthermalmove-
mine the applicability of regulatory limitations prior to use.
ments.
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.2 Thisguidespecificallyexcludesdimensionstoneusedin
ization established in the Decision on Principles for the
interior building surfaces, flooring or paving, slate dimension
Development of International Standards, Guides and Recom-
stone used as roofing. Though they share some similar assess-
mendations issued by the World Trade Organization Technical
ment and maintenance concerns, thin stone (less than 2 in.
Barriers to Trade (TBT) Committee.
nominal thickness) exterior cladding, and stone cladding at-
tached to metal flames are also excluded due to their unique
2. Referenced Documents
design characteristics and performance requirements.Although
procedures and cautions listed herein may apply to walls and 2.1 ASTM Standards:
facades containing semi-dimension, or partially sized, stone in C119 Terminology Relating to Dimension Stone
the form of split-face, or rubble and to stone-facade concrete C1515 Guide for Cleaning of Exterior Dimension Stone,
panels, the guide is not specifically directed to such stone use. Vertical And Horizontal Surfaces, New or Existing
It does not address removal of small-area stains. E1971 Guide for Stewardship for the Cleaning of Commer-
cial and Institutional Buildings
1.3 This guide offers an organized collection of information
oraseriesofoptionsanddoesnotrecommendaspecificcourse
3. Terminology
of action. This document cannot replace education or experi-
3.1 Terms used in this guide are defined in Terminology
ence and should be used in conjunction with the judgment of
C119.
3.2 Definitions of Terms Specific to This Standard:
This guide is under the jurisdiction of ASTM Committee C18 on Dimension
Stone and is the direct responsibility of Subcommittee C18.07 on Environmental
Properties, Behavior, and Cleaning. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2018. Published November 20018. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2001. Last previous edition approved in 2011 as C1496–11. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1496-18. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1496 − 18
3.2.1 crack monitor—any of the several two-part devices should be done under the observation of a qualified stone
that can be attached to stone masonry in such a way that they consultanttoensuretheuseofpropermaterialsandtechniques.
can span cracks in order to periodically measure changes in
5.4 Personnel responsible for stone facade maintenance
crack width thereby indicating movement.
should be familiar with the systems used in the construction of
3.2.2 dutchman—repair used to patch stone masonry with a
their buildings on at least an elementary level. Prior to
section of new stone. The damaged area within a particular
inspections, they should be briefed by personnel knowledge-
stone element is removed. The remaining void is trimmed to a
able about the building and its construction, particularly the
regularshape.Anewpieceofstone,or“dutchman,”iscutfrom
stonewallsystem.Thisbackgroundshouldhelpindetermining
matching stone cut slightly smaller than the area to be filled. It
when the engagement of a qualified stone consultant should be
is installed using dowels or some other mechanical attachment,
considered.
then adhered, or mortared into place.
5.5 In cases where the building or its facade has cultural,
3.2.3 exfoliation—deterioration or loss of certain types of
civic, historic, or architectural significance, consultation with a
stone in the form of flakes, scales, and layers.
specialist is recommended.
3.2.4 qualified stone consultant—persons having expertise
5.6 When assessing the condition of exterior dimension
in the assessment and repair of stone masonry. These may
stone, and particularly any problems requiring action, the
include independent consultants such as architects, engineers,
appropriate cleaning or repair methods should promote eco-
material scientists such as mineralogist or geologists, or stone
efficiency, avoid any adverse impacts on humans present or
masonry contractors.
involved, avoid any adverse impacts on the building structure,
3.2.5 thick—stones with a nominal bed-depth of 2 in. (5 cm) and reduce stress on the environment. See Guide E1971.
or more. Choices must be made on cleaning products and processes, and
building repair materials and method.
4. Significance and Use
5.6.1 Certain pertinent questions should be considered here:
(1) how is the building used? (2) what type of dimension stone
4.1 This guide attempts to provide information to assist
and what finish was used? (3) is the dimension stone load-
buildingownersandmanagerswithlimitedknowledgeofstone
bearing or is the load carried by other materials such as steel or
construction to recognize basic problems with performance of
concrete? (4) are there any issues relating to building age or
facades, and to keep them in good condition through periodic
architecture? (5) what criteria or measures will be used to
inspections and maintenance. Increased awareness of the
evaluate the quality of cleaning and repairs?
behavior of stone masonry facades and associated materials
can reduce maintenance and replacement costs by addressing
6. Guidelines for Inspections
problems and deterioration early.
6.1 Schedule Inspections—Schedule and perform semi-
4.2 The objective of all maintenance should be to limit
annual inspections of stone wall elements. Inspect all eleva-
deterioration through early intervention.
tions of the building. A walk-around visual survey with a
4.3 When it appears damage to stone support elements has
camera and binoculars should be a minimum procedure. Use
occurred, a qualified stone consultant should be employed to
adjacent buildings’ roofs and windows to gain same-level
evaluate the support conditions, as well as recommend meth-
access, to examine building facades and associated elements.
ods to restore the building’s integrity and preserve public
Use building windows and set-backs where possible for
safety.
additional vantage points. If the available access is not suffi-
cient to perform the inspections, then consider methods, as
5. Introduction
outlined in 6.3. Photograph any observed distress or problem
5.1 An effective maintenance program for exterior stone areas for later reference in determining appropriate repairs.
masonry should incorporate preventive maintenance among its
6.2 Condition Documentation/Monitoring—Keep accurate
key elements. Early attention to problems, and simple mea-
and cumulative records of inspection findings. Buildings con-
sures to remedy them, will often avoid costly renovation later.
structed of thick dimension stone with mortar or sealant-filled
This guide is intended to help interested personnel locate such
joints react slowly to environmental forces. Knowledge of the
problem areas, better understand potential causes of stone
timingofacondition’sonsetandunderstandingitsprogressaid
deterioration, and identify appropriate corrective measures for
in assessing the distressed condition. Monitor critical or
the observed deficiencies.
deteriorated areas between scheduled inspections. Use mea-
5.2 Maintenance supervisors should understand how their surements or crack monitors to measure changes in cracks,
building is constructed to apply this guide and better maintain increasing lippage between stones (stones projecting or retreat-
theirbuildings.Employingaqualifiedstoneconsultanttoassist ing in plane from the adjacent stones), or other changes and
them in interpreting pertinent drawings and documents, and displacements in stone position. Well-kept records will aid in
initially inspecting conditions should help them become effec- the diagnosis of the specific causes of the conditions observed,
tive observers of stone performance. should a qualified stone consultant be required.
5.3 This guide lists many typical problems that can affect 6.3 Tall Buildings—Inspections of buildings with heights
stone masonry, facades. It describes likely causes, and dis- that exceed those readily observable with binoculars, or with
cusses common repair methods. All initial attempts at repairs limited vantage points require more detailed planning. It will
C1496 − 18
be necessary to view representative areas of the facades from reducing clearances and creating stress concentrations.
suspended or fixed scaffolding, mobile work platforms, or Trapped water can freeze and expand, causing the stone to
personnel lifts to adequately observe existing conditions. weaken, and eventually spall or crack. Joint materials may also
deteriorate as a result.
7. Procedure for Evaluation of Stone Conditions
9.1.1 Water can also carry minerals, chemicals, or other
7.1 At a minimum, the following procedure should be used contaminants that can be deposited on or within the stone and
as a guide to decide an appropriate course of action for
joints, causing discoloration, staining, or deterioration.
observed deficiencies as part of an inspection and maintenance
9.1.2 Wetness, staining, or darkening may be due to trapped
program for stone masonry facades.
moisture. Discoloration or deposition of efflorescence (a pow-
7.1.1 Identify and document the defects.
dery white or gray accretion on stone faces) may also be
7.1.2 Note the extent of the defects, patterns or concentra-
evidence of moisture entry, or “rising damp.” Rising damp is a
tions of distress.
condition in which the stones appear darker due to water
7.1.3 Postulate the likely causes.
wicking into the stone by capillary action from a water source
7.1.4 Perform necessary maintenance or obtain assistance
along one or more edges of the stone, such as at the base of a
with repairs:
building.
7.1.4.1 If the condition is stable and does not appear to be
9.2 Joints—Every inspection should include a review of
progressive, perform appropriate maintenance, and simple or
each joint between stones. Document anomalous and suspect
temporary repairs.
conditions photographically, especially in areas of accelerated
7.1.4.2 If the cause is not apparent, and the condition
deterioration. Where a problem is suspected, it is useful to
appears stable and not progressive, monitor the condition and
compare photographs taken at various times to establish the
consult with a qualified stone consultant to determine the cause
progression and rate of deterioration.
and appropriate repairs.
9.2.1 Look for missing mortar and sealant, for cracks in
7.1.4.3 If the observed conditions are considered dangerous
mortar, for partings between mortar or sealant and the stone,
or progressive, obtain assistance from a qualified stone con-
for non-uniform joint sizes due to tight, closed or opening
sultant immediately.
joints, and for lipped stones. Connections between stones and
8. Maintenance
non-stone materials such as windows and other openings are
often particularly susceptible to racking and eccentric move-
8.1 Routine Maintenance—Many problems can begin or
ment. Check for plugged weep holes throughout the wall
worsen due to neglect of routine maintenance. Stone masonry
system. Compare the width of expansion, control, and con-
itself, when used in an exterior application, requires periodic
struction joints. Look for wider or narrower tops and bottoms
joint repairs, such as sealant replacement, tuck pointing, and
of such joints.
cleaning. Stone facade components can also be affected by a
lack of maintenance of other building systems, such as roofs,
9.3 Stone—Cracks and spalled areas at or near joints may
parapets, windows, and flashing.
indicate excessive compression loading, anchor failure, and
8.2 Cleaning—Regular cleaning is also critical to the long environmental deterioration, among other things. Misalign-
ment of stone across a series of joints may indicate local or
term durability of natural stone facades, as well as their
appearance. Cleaning methods should be selected that do not structural building movements.
damage the stone. Cleaning methods and materials should be
9.3.1 Surface deterioration may take the form of exfoliation
first tested, from the least to the most aggressive, to determine
(where the surface is lost in thin layers), spalling, powdering,
the mildest treatment that provides satisfactory results. Prior to
or chipping. These conditions can be particularly prevalent
implementing a cleaning technique building-wide, test areas
where chloride-based de-icing products used on paving sys-
should be cleaned using the pro
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C1496 − 11 C1496 − 18
Standard Guide for
Assessment and Maintenance of Exterior Dimension Stone
Masonry Walls and Facades
This standard is issued under the fixed designation C1496; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide outlines how to visually assess exterior stone masonry walls and facades to determine their general condition.
Examining key features of the construction can help identify and diagnose problems which require repairs or corrective action.
Such an examination can expose conditions which may be addressed with maintenance and minor repairs, or may require expert
assistance. This guide is not intended to be used for buildings requiring major exterior rehabilitation or structural repairs.
1.1.1 This guide applies to walls of solid stone or dimension stone used as a cladding. Stone cladding is typically connected
to a backup material with a variety of anchoring methods, including traditional hand-set masonry anchors such as straps, dowels,
cramps, hook-and-eyes, dove-tails, wire ties, and the like. Joints between stones in these types of buildings are usually filled with
mortar or sealant. Sealant-filled joints are usually designed to accommodate structural and thermal movements.
1.2 This guide specifically excludes dimension stone used in interior building surfaces, flooring or paving, slate dimension stone
used as roofing. Though they share some similar assessment and maintenance concerns, thin stone (less than 2 in. nominal
thickness) exterior cladding, and stone cladding attached to metal flames are also excluded due to their unique design
characteristics and performance requirements. Although procedures and cautions listed herein may apply to walls and facades
containing semi-dimension, or partially sized, stone in the form of split-face, or rubble and to stone-facade concrete panels, the
guide is not specifically directed to such stone use. It does not address removal of small-area stains.
1.3 This guide offers an organized collection of information or a series of options and does not recommend a specific course
of action. This document cannot replace education or experience and should be used in conjunction with professional judgment.
the judgment of stone restoration design consultants. Not all aspects of this guide may be applicable in all circumstances. This
ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional stone
consultants service must be judged, nor should this document be applied without consideration of a project’s many unique aspects.
The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus
process.
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This guide is under the jurisdiction of ASTM Committee C18 on Dimension Stone and is the direct responsibility of Subcommittee C18.07 on Environmental Properties,
Behavior, and Cleaning.
Current edition approved Oct. 1, 2011Nov. 1, 2018. Published November 20011November 20018. Originally approved in 2001. Last previous edition approved in
20092011 as C1496–09.C1496–11. DOI: 10.1520/C1496-11.10.1520/C1496-18.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1496 − 18
2. Referenced Documents
2.1 ASTM Standards:
C119 Terminology Relating to Dimension Stone
C1515 Guide for Cleaning of Exterior Dimension Stone, Vertical And Horizontal Surfaces, New or Existing
E1971 Guide for Stewardship for the Cleaning of Commercial and Institutional Buildings
3. Terminology
3.1 Terms used in this guide are defined in Terminology C119.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 crack monitor—any of the several two-part devices that can be attached to stone masonry in such a way that they can span
cracks in order to periodically measure changes in crack width thereby indicating movement.
3.2.2 dutchman—repair used to patch stone masonry with a section of new stone. The damaged area within a particular stone
element is removed. The remaining void is trimmed to a regular shape. A new piece of stone, or “dutchman,” is cut from matching
stone cut slightly smaller than the area to be filled. It is installed using dowels or some other mechanical attachment, then adhered,
or mortared into place.
3.2.3 exfoliation—deterioration or loss of certain types of stone in the form of flakes, scales, and layers.
3.2.4 professional assistance—qualified stone consultant—independent opinions and recommendations provided by persons
having expertise in the assessment and repair of stone masonry. Such professionals These may include independent consultants
such as architects, engineers, material scientists such as mineralogist or geologists, or stone masonry contractors.
3.2.5 thick—stones with a nominal bed-depth of 2 in. (5 cm) or more.
4. Significance and Use
4.1 This guide attempts to provide information to assist building owners and managers with limited knowledge of stone
construction to recognize basic problems with performance of facades, and to keep them in good condition through periodic
inspections and maintenance. Increased awareness of the behavior of stone masonry facades and associated materials can reduce
maintenance and replacement costs by addressing problems and deterioration early.
4.2 The objective of all maintenance should be to limit deterioration through early intervention.
4.3 When it appears damage to stone support elements has occurred, professionals a qualified stone consultant should be
consultedemployed to evaluate the support conditions, as well as recommend methods to restore the building’s integrity and
preserve public safety.
5. Introduction
5.1 An effective maintenance program for exterior stone masonry should incorporate preventive maintenance among its key
elements. Early attention to problems, and simple measures to remedy them, will often avoid costly renovation later. This guide
is intended to help interested personnel locate such problem areas, better understand potential causes of stone deterioration, and
identify appropriate corrective measures for the observed deficiencies.
5.2 Maintenance supervisors should understand how their building is constructed to apply this guide and better maintain their
buildings. Employing a professional qualified stone consultant to assist them in interpreting pertinent drawings and documents, and
initially inspecting conditions should help them become effective observers of stone performance.
5.3 This guide lists many typical problems that can affect stone masonry, facades. It describes likely causes, and discusses
common repair methods. All initial attempts at repairs should be done under the observation of a professional qualified stone
consultant to ensure the use of proper materials and techniques.
5.4 Personnel responsible for stone facade maintenance should be familiar with the systems used in the construction of their
buildings on at least an elementary level. Prior to inspections, they should be briefed by personnel knowledgeable about the
building and its construction, particularly the stone wall system. This background should help in determining when the engagement
of a professional qualified stone consultant should be considered.
5.5 In cases where the building or its facade has cultural, civic, historic, or architectural significance, consultation with a
specialist is recommended.
5.6 When assessing the condition of exterior dimension stone, and particularly any problems requiring action, the appropriate
cleaning or repair methods should promote eco-efficiency, avoid any adverse impacts on humans present or involved, avoid any
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
C1496 − 18
adverse impacts on the building structure, and reduce stress on the environment. See Guide E1971. Choices must be made on
cleaning products and processes, and building repair materials and method.
5.6.1 Certain pertinent questions should be considered here: (1) how is the building used? (2) what type of dimension stone and
what finish was used? (3) is the dimension stone load-bearing or is the load carried by other materials such as steel or concrete?
(4) are there any issues relating to building age or architecture? (5) what criteria or measures will be used to evaluate the quality
of cleaning and repairs?
6. Guidelines for Inspections
6.1 Schedule Inspections—Schedule and perform semi-annual inspections of stone wall elements. Inspect all elevations of the
building. A walk-around visual survey with a camera and binoculars should be a minimum procedure. Use adjacent buildings’ roofs
and windows to gain same-level access, to examine building facades and associated elements. Use building windows and set-backs
where possible for additional vantage points. If the available access is not sufficient to perform the inspections, then consider
methods, as outlined in 6.3. Photograph any observed distress or problem areas for later reference in determining appropriate
repairs.
6.2 Condition Documentation/Monitoring—Keep accurate and cumulative records of inspection findings. Buildings constructed
of thick dimension stone with mortar or sealant-filled joints react slowly to environmental forces. Knowledge of the timing of a
condition’s onset and understanding its progress aid in assessing the distressed condition. Monitor critical or deteriorated areas
between scheduled inspections. Use measurements or crack monitors to measure changes in cracks, increasing lippage between
stones (stones projecting or retreating in plane from the adjacent stones), or other changes and displacements in stone position.
Well-kept records will aid in the diagnosis of the specific causes of the conditions observed, should more experienced professionals
a qualified stone consultant be required.
6.3 Tall Buildings—Inspections of buildings with heights that exceed those readily observable with binoculars, or with limited
vantage points require more detailed planning. It will be necessary to view representative areas of the facades from suspended or
fixed scaffolding, mobile work platforms, or personnel lifts to adequately observe existing conditions.
7. Procedure for Evaluation of Stone Conditions
7.1 At a minimum, the following procedure should be used as a guide to decide an appropriate course of action for observed
deficiencies as part of an inspection and maintenance program for stone masonry facades.
7.1.1 Identify and document the defects.
7.1.2 Note the extent of the defects, patterns or concentrations of distress.
7.1.3 Postulate the likely causes.
7.1.4 Perform necessary maintenance or obtain assistance with repairs:
7.1.4.1 If the condition is stable and does not appear to be progressive, perform appropriate maintenance, and simple or
temporary repairs.
7.1.4.2 If the cause is not apparent, and the condition appears stable and not progressive, monitor the condition and consult with
professionals a qualified stone consultant to determine the cause and appropriate repairs.
7.1.4.3 If the observed conditions are considered dangerous or progressive, obtain professional assistance assistance from a
qualified stone consultant immediately.
8. Maintenance
8.1 Routine Maintenance—Many problems can begin or worsen due to neglect of routine maintenance. Stone masonry itself,
when used in an exterior application, requires periodic joint repairs, such as sealant replacement, tuck pointing, and cleaning. Stone
facade components can also be affected by a lack of maintenance of other building systems, such as roofs, parapets, windows, and
flashing.
8.2 Cleaning—Regular cleaning is also critical to the long term durability of natural stone facades, as well as their appearance.
Cleaning methods should be selected that do not damage the stone. Cleaning methods and materials should be first tested, from
the least to the most aggressive, to determine the mildest treatment that provides satisfactory results. Prior to implementing a
cleaning technique building-wide, test areas should be cleaned using the proposed methods. The areas should be evaluated for a
minimum period of six weeks to assess the results. Improper selection of cleaning chemicals and procedures will produce unsightly
and irreversible damage to the appearance, and potentially the structural integrity, of the stone facade components. Refer to Guide
C1515 for procedures for cleaning exterior stone.
9. Areas of Focus for Inspection
9.1 Moisture or Water Staining—Look for signs of moisture on interior and exterior surfaces, as well as throughout the stone
wall system. Water penetration can lead not only to deterioration of interior finishes, but also to stone and joint material degradation
and corrosion of anchor system components if the water is trapped behind or within the wall or facade system for prolonged
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periods. Water absorbed into stone and joint materials can cause dimensional changes, potentially reducing clearances and creating
stress concentrations. Trapped water can freeze and expand, causing the stone to weaken, and eventually spall or crack. Joint
materials may also deteriorate as a result.
9.1.1 Water can also carry minerals, chemicals, or other contaminants that can be deposited on or within the stone and joints,
causing discoloration, staining, or deterioration.
9.1.2 Wetness, staining, or darkening may be due to trapped moisture. Discoloration or deposition of efflorescence (a powdery
white or gray accretion on stone faces) may also be evidence of moisture entry, or “rising damp.” Rising damp is a condition in
which the stones appear darker due to water wicking into the stone by capillary action from a water source along one or more edges
of the stone, such as at the base of a building.
9.2 Joints—Every inspection should include a review of each joint between stones. Document anomalous and suspect conditions
photographically, especially in areas of accelerated deterioration. Where a problem is suspected, it is useful to compare
photographs taken at various times to establish the progression and rate of deterioration.
9.2.1 Look for missing mortar and sealant, for cracks in mortar, for partings between mortar or sealant and
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