ASTM C1394-20

Standard Guide for In-Situ Structural Silicone Glazing Evaluation

SIGNIFICANCE AND USE
4.1 Guidelines are provided for the procedures to evaluate existing SSG installations, including two- and four-sided installations. Due to the unlimited range of materials that may be used in a particular building, the information contained in this guide is general in nature. For a discussion of new SSG installations, refer to Guide C1401.  
4.2 Typical conditions are listed that might be discovered during, or suggest the need for, such evaluations. Guidelines are also suggested for times to perform evaluations. These guidelines are also necessarily general. Professional judgment of a qualified person should be used in determining the appropriate time to perform an evaluation on a particular building.  
4.3 This guide should not be the only reference consulted when determining the scope of a proposed evaluation. For example, the local building code and the manufacturers' product literature for the actual materials used (if known) should also be considered.  
4.4 This document is not a substitute for experience and judgment in assessing the condition of the specialized types of construction discussed.
SCOPE
1.1 The existing condition of SSG installations should be periodically evaluated in-situ to detect if problems exist, and if so found, to address them before they become severe or pervasive. Evaluation of existing SSG installations is required by certain building codes and local ordinances. This guide provides a program to evaluate the existing conditions, lists typical conditions that may exist, and suggests times when such evaluations are appropriate. Presently, only a silicone sealant that is specifically formulated, tested and marketed as a structural glazing sealant is allowed for structural sealant glazing. The committee with jurisdiction over this standard is not aware of any comparable standards published by any other organizations.  
1.2 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.

General Information

• Status: Published
• Publication Date: 30-Apr-2020
• ICS: 81.040.20 - Glass in building
• Technical Committee: C24 - Building Seals and Sealants
• Drafting Committee: C24.10 - Specifications, Guides and Practices

Relations

• Refers: ASTM C1521-19(2020) - Standard Practice for Evaluating Adhesion of Installed Weatherproofing Sealant Joints
• Effective Date: 01-May-2020
• Refers: ASTM C1392-20 - Standard Guide for Evaluating Failure of Structural Sealant Glazing
• Effective Date: 01-Jan-2020
• Refers: ASTM C1521-19 - Standard Practice for Evaluating Adhesion of Installed Weatherproofing Sealant Joints
• Effective Date: 01-Aug-2019
• Refers: ASTM C717-19 - Standard Terminology of Building Seals and Sealants
• Effective Date: 01-Mar-2019
• Refers: ASTM C717-18 - Standard Terminology of Building Seals and Sealants
• Effective Date: 01-Mar-2018
• Refers: ASTM C717-17a - Standard Terminology of Building Seals and Sealants
• Effective Date: 01-Nov-2017
• Refers: ASTM C717-17 - Standard Terminology of Building Seals and Sealants
• Effective Date: 01-Jan-2017
• Refers: ASTM C717-16a - Standard Terminology of Building Seals and Sealants
• Effective Date: 15-Nov-2016
• Refers: ASTM C717-16 - Standard Terminology of Building Seals and Sealants
• Effective Date: 01-Sep-2016
• Refers: ASTM C717-14a - Standard Terminology of Building Seals and Sealants
• Effective Date: 01-May-2014
• Refers: ASTM C717-14 - Standard Terminology of Building Seals and Sealants
• Effective Date: 01-Feb-2014
• Refers: ASTM C1392-00(2014) - Standard Guide for Evaluating Failure of Structural Sealant Glazing
• Effective Date: 01-Jan-2014
• Refers: ASTM C717-13 - Standard Terminology of Building Seals and Sealants
• Effective Date: 01-Nov-2013
• Refers: ASTM C1521-13 - Standard Practice for Evaluating Adhesion of Installed Weatherproofing Sealant Joints
• Effective Date: 01-May-2013
• Refers: ASTM C717-12b - Standard Terminology of Building Seals and Sealants
• Effective Date: 01-Dec-2012

Overview

ASTM C1394-20: Standard Guide for In-Situ Structural Silicone Glazing Evaluation outlines general procedures for assessing the condition of existing Structural Sealant Glazing (SSG) installations. Structural silicone glazing, commonly applied in modern building facades, relies on silicone sealants to bond glass and panels directly to supporting frames, often with minimal visible framing. As these installations age, periodic evaluation is essential to confirm the continued performance, durability, and safety of the sealant and the entire façade system.

This guide applies to both two-sided and four-sided SSG assemblies and emphasizes the importance of professional judgment when determining the scope and timing of evaluations. The guide complements but does not substitute for local building codes, manufacturers’ recommendations, or the expertise of qualified professionals.

Key Topics

• Evaluation Procedures: Details on inspection levels, assessment methods, and conditions that may signal the need for review. Evaluations should be supervised by a qualified person with expertise in structural sealant glazing.

• Typical Conditions to Assess:

  • Symptoms such as glass breakage, air or water infiltration, condensation, organic growth, or visible sealant failure
  • Structural indications including loss of adhesion, fluid migration, sealant discoloration, and poor sealant joint geometry

• Times to Perform Evaluations:

  • After disruptive events (natural or man-made disasters)
  • Following product recalls or published concerns
  • During changes of ownership or major facade repairs
  • At regular intervals: after installation, before warranty expiry, and periodically (such as 1, 5, 10, 15, and 20 years post-installation)

• Documentation and Reporting:

  • Recording the evaluation findings, methods, and any recommended remedial actions in standardized, easily comparable formats for future reference

• Consulting Other Resources: Guidance stresses the necessity of referring also to building codes and manufacturer’s data for comprehensive assessment.

Applications

ASTM C1394-20 provides practical value to building owners, facility managers, architects, and façade consultants by:

• Supporting compliance with local regulations and building codes that require periodic façade safety inspections
• Helping identify early symptoms of SSG distress or failure, allowing timely remedial actions to extend façade lifespan and ensure occupant safety
• Providing structured procedures for assessment, which can be integrated into building maintenance programs and risk management practices
• Enabling quality assurance for building acquisitions, especially in due diligence evaluations during property transactions
• Facilitating ongoing maintenance planning by documenting changes and observations over the lifecycle of SSG installations

This guide is particularly relevant for high-rise buildings, commercial properties, and urban developments where structural silicone glazing is prevalent and access for inspection may be limited.

Related Standards

The ASTM C1394-20 standard references and complements several other ASTM standards for construction and building sealant evaluation, including:

• ASTM C717 - Terminology of Building Seals and Sealants
• ASTM C1392 - Guide for Evaluating Failure of Structural Sealant Glazing
• ASTM C1401 - Guide for Structural Sealant Glazing (for new installations)
• ASTM C1521 - Practice for Evaluating Adhesion of Installed Weatherproofing Sealant Joints

Building professionals are encouraged to consult related standards alongside ASTM C1394-20 to ensure comprehensive understanding and robust evaluation of structural silicone glazing systems.

Keywords: structural silicone glazing, SSG evaluation, sealant durability, building facade inspection, ASTM C1394-20, in-situ glazing assessment, structural sealant joint, glazing maintenance, structural sealant glazing standard

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: C1394 − 20
Standard Guide for
In-Situ Structural Silicone Glazing Evaluation
This standard is issued under the fixed designation C1394; 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.
INTRODUCTION
Structural Sealant Glazing (SSG) is a unique method of retaining glass or other panels via adhesive
bonding using a structural sealant. Emerging in the mid-to-late 1960s, SSG applications used silicone
sealants to transfer wind loads along two opposing sides of glass; a construction method which came
to be known as “two-sided” SSG. By 1971, the technique began incorporating load transfer along all
four sides of glass and the first “four-sided” SSG installation was built at 455 West Fort Street in
Detroit,Michigan.Sincethen,buildingscontainingtwo-orfour-sided(or,occasionally,othernumbers
of sides) SSG walls have been constructed within many cities, some exceeding 100 stories
While SSG popularity has increased since its inception, concerns remain over potential failures due
to the increasing number of buildings constructed using this method that are aging; unknown overall
structural sealant durability; and the fact that the adhesive bond in the SSG system remains largely
concealed from visual inspection, creating concern on SSG systems in general. This guide addresses
these concerns by providing suggestions for in-situ evaluations of completed installations of any age.
1. Scope 2. Referenced Documents
1.1 The existing condition of SSG installations should be
2.1 ASTM Standards:
periodically evaluated in-situ to detect if problems exist, and if
C717 Terminology of Building Seals and Sealants
so found, to address them before they become severe or
C1392 Guide for Evaluating Failure of Structural Sealant
pervasive. Evaluation of existing SSG installations is required
Glazing
by certain building codes and local ordinances. This guide
C1401 Guide for Structural Sealant Glazing
provides a program to evaluate the existing conditions, lists
C1521 Practice for EvaluatingAdhesion of Installed Weath-
typical conditions that may exist, and suggests times when
erproofing Sealant Joints
such evaluations are appropriate. Presently, only a silicone
sealant that is specifically formulated, tested and marketed as a
3. Terminology
structural glazing sealant is allowed for structural sealant
3.1 Definitions:The definitions of the following terms used
glazing. The committee with jurisdiction over this standard is
inthisguidearefoundinTerminologyC717:structuralsealant;
not aware of any comparable standards published by any other
structural sealant glazing; two-sided structural sealant glazing;
organizations.
four-sided structural sealant glazing; fluid migration.
1.2 This international standard was developed in accor-
3.2 Definitions of Terms Specific to This Standard:
dance with internationally recognized principles on standard-
3.2.1 qualified person—one with a recognized degree or
ization established in the Decision on Principles for the
professional registration and extensive knowledge and experi-
Development of International Standards, Guides and Recom-
ence in the field of structural sealant glazing, and who is
mendations issued by the World Trade Organization Technical
capable of design, analysis, evaluation, and interpretation of
Barriers to Trade (TBT) Committee.
specifications in the subject.
ThisguideisunderthejurisdictionofASTMCommitteeC24onBuildingSeals
and Sealants and is the direct responsibility of Subcommittee C24.10 on
Specifications, Guides and Practices. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2020. Published June 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approvedin1998.Lastpreviouseditionapprovedin2012asC1394–03(2012).DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1394-20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1394 − 20
4. Significance and Use 5.2.4 Between 1 and 2 years after substantial completion,
Level 1;
4.1 Guidelines are provided for the procedures to evaluate
5.2.5 After 5 years, Level 1;
existing SSG installations, including two- and four-sided
5.2.6 After 10 years, Level 2;
installations. Due to the unlimited range of materials that may
5.2.7 After 15 years, Level 1 (if Level 2 was performed as
be used in a particular building, the information contained in
recommended after 10 years); and
this guide is general in nature. For a discussion of new SSG
5.2.8 After 20 years, and each successive 10 years, Level 2.
installations, refer to Guide C1401.
4.2 Typical conditions are listed that might be discovered
6. Symptoms of Problems With SSG
during, or suggest the need for, such evaluations. Guidelines
6.1 Whether due to original construction mistakes or latent
are also suggested for times to perform evaluations. These
defects, SSG installations sometimes exhibit distress. The
guidelines are also necessarily general. Professional judgment
following list summarizes conditions that may indicate poor
of a qualified person should be used in determining the
original construction or a subsequent failure of the structural
appropriate time to perform an evaluation on a particular
sealant, and therefore require evaluation. This list may not be
building.
all-inclusive.
4.3 This guide should not be the only reference consulted
6.1.1 Glass breakage from an unknown cause—There are
when determining the scope of a proposed evaluation. For
numerous potential causes of spontaneous glass breakage; if
example, the local building code and the manufacturers’
the cause is unknown, then it should be investigated prior to
product literature for the actual materials used (if known)
glass replacement whether an SSG defect contributed to the
should also be considered.
failure.
4.4 This document is not a substitute for experience and 6.1.2 Air or water infiltration—If air or water migrates
through or to the structural sealant joint, then it must also have
judgment in assessing the condition of the specialized types of
construction discussed. lost its structural function—at least for part of its length.
Symptoms of air or water leakage include:
6.1.2.1 Visible accumulation of liquid water during or
5. Reasons to Perform an Evaluation
following storms;
5.1 There are numerous reasons that a building owner or
6.1.2.2 Wet insulation;
manager (hereinafter “owner”) may choose to evaluate an SSG
6.1.2.3 Organic growth;
system, whether discretionary or to comply with an ordinance.
6.1.2.4 Water stains or salt deposits;
The recommended evaluation levels, as discussed in Section 7,
6.1.2.5 Audible rattle or whistle;
are referenced for each situation. The findings from one level
6.1.2.6 Discoloration of laminated glazing;
of investigation may trigger the need for a more in-depth
6.1.2.7 Condensation or frost on glazing;
investigation. At a minimum, it is recommended that an
6.1.2.8 Fogging of insulated glass units;
existing SSG installation be evaluated when triggered by any
6.1.2.9 Opacifier failure on spandrel or other glass—
of the following events:
Moisture is a factor in the failure of some opacifiers, and may
5.1.1 Afteranaturaldisaster,suchasanearthquakeormajor
indicate water infiltration; and
wind storm, or a man-made disaster such as a bomb blast,
6.1.2.10 Visible sealant failures— Sealant failures may be
Level 2;
observed from inside or outside, depending on the design, and
5.1.2 After a recall or published concern over a specific
may involve the weather-seal joint as well as the structural
product or system, Level 1;
joint. Visible manifestations of sealant failures include:
5.1.3 Upon a change of property ownership, Level 1;
(1) Intermittent loss of adhesion—Nonadhered sealant may
5.1.4 Before repeating a novel, unique or atypical design,
differ in iridescence or reflectivity compared to adhered sealant
Level
...

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: C1394 − 03 (Reapproved 2012) C1394 − 20
Standard Guide for
In-Situ Structural Silicone Glazing Evaluation
This standard is issued under the fixed designation C1394; 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.
INTRODUCTION
SSG is popular because of itsStructural Sealant Glazing (SSG) is a unique method of retaining glass
or other panels in smooth exterior walls, interrupted only by narrow sealant joints. The first four-sided
SSG in commercial construction is on the former corporate headquarters building of SHG
Incorporated (formerly known as Smith, Hinchman & Grylls) in Detroit, MI, built in 1971. via
adhesive bonding using a structural sealant. Emerging in the mid-to-late 1960s, SSG applications used
silicone sealants to transfer wind loads along two opposing sides of glass; a construction method
which came to be known as “two-sided” SSG. By 1971, the technique began incorporating load
transfer along all four sides of glass and the first “four-sided” SSG installation was built at 455 West
Fort Street in Detroit, Michigan. Since then, buildings containing two- or four-sided (or, occasionally,
other numbers of sides of nonrectangular-shaped panels) sides) SSG walls have been constructed
within mostmany cities, some as tall as 80 stories.exceeding 100 stories
While SSG popularity increases, the sealant industry remains concerned has increased since its
inception, concerns remain over potential failures due to the increasing number of buildings
containing structural glazing constructed using this method that are aging; unknown overall structural
sealant durability; and the level of understanding of the principles of SSG by glazers. fact that the
adhesive bond in the SSG system remains largely concealed from visual inspection, creating concern
on SSG systems in general. This guide addresses these concerns by providing suggestions for in situ
in-situ evaluations of completed installations of any age.
1. Scope
1.1 It is recommended to periodically evaluate the The existing condition of structural sealant glazing (hereinafter called SSG)
installations in situ to detect problems SSG installations should be periodically evaluated in-situ to detect if problems exist, and
if so found, to address them before they become severe or pervasive. Evaluation of existing SSG installations areis required by
certain building codes and local ordinances. This guide provides a program to evaluate the existing conditions, lists typical
conditions, which might be found, conditions that may exist, and suggests times when such evaluations are appropriate. Presently,
only a silicone sealant that is specifically formulated, tested and marketed as a structural glazing sealant is allowed for structural
sealant glazing. The committee with jurisdiction over this standard is not aware of any comparable standards published by any
other organizations.
1.2 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.
2. Referenced Documents
2.1 ASTM Standards:
C717 Terminology of Building Seals and Sealants
C1392 Guide for Evaluating Failure of Structural Sealant Glazing
This guide is under the jurisdiction of ASTM Committee C24 on Building Seals and Sealants and is the direct responsibility of Subcommittee C24.10 on Specifications,
Guides and Practices.
Current edition approved Dec. 1, 2012May 1, 2020. Published December 2012June 2020. Originally approved in 1998. Last previous edition approved in 20082012 as
C1394–03(2008).C1394–03(2012). DOI: 10.1520/C1394-03R12.10.1520/C1394-20.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1394 − 20
C1401 Guide for Structural Sealant Glazing
C1521 Practice for Evaluating Adhesion of Installed Weatherproofing Sealant Joints
3. Terminology
3.1 Definitions:The definitions of the following terms used in this guide are found in Terminology C717: structural sealant;
structural sealant glazing; two-sided structural sealant glazing; four-sided structural sealant glazing; fluid migration.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 qualified person—one with a recognized degree or professional registration and extensive knowledge and experience in
the field of structural sealant glazing, and who is capable of design, analysis, evaluation, and interpretation of specifications in the
subject.
4. Significance and Use
4.1 Guidelines are provided for the procedures to evaluate existing SSG installations, including two- and four-sided
installations. Due to the unlimited range of materials that may be used in a particular building, the information contained in this
guide is general in nature. For a discussion of new SSG installations, refer to Guide C1401.
4.2 Typical conditions are listed that might be discovered during, or suggest the need for, such evaluations. Guidelines are also
suggested for times to perform evaluations. These guidelines are also necessarily general. Professional judgment of a qualified
person should be used in determining the appropriate time to perform an evaluation on a particular building.
4.3 This guide should not be the only reference consulted when determining the scope of a proposed evaluation. For example,
the local building code and the manufacturers’ product literature for the actual materials used (if known) should also be considered.
4.4 This document is not a substitute for experience and judgment in assessing the condition of the specialized types of
construction discussed.
5. Reasons to Perform an Evaluation
5.1 There are numerous reasons that a building owner or manager (hereinafter “owner”) may choose to evaluate an SSG system,
whether discretionary or to comply with an ordinance. The recommended evaluation levels, as discussed in Section 7, are
referenced for each situation. The findings from one level of investigation may trigger the need for a more in-depth investigation.
At a minimum, it is recommended that an existing SSG installation be evaluated when triggered by any of the following events:
5.1.1 After a natural disaster, such as an earthquake or major wind storm, or a man-made disaster such as a bomb blast, Level
2;
5.1.2 After a recall or published concern over a specific product or system, Level 1;
5.1.3 Upon a change of property ownership, Level 1;
5.1.4 Before repeating a new novel, unique or atypical design, Level 1;
5.1.5 As dictated by government regulations, Level 1 or 2; or
5.1.6 When distress is discovered (see Section 8), Level 2, or, if prevalent distress is found, Level 3.
5.2 In addition to event-triggered evaluations, it is recommended that proactive owners also perform periodic evaluations at the
following intervals: (Note that some of these periods may overlap. If distress is found during any evaluation, then more frequent
and more in-depth evaluations should be considered.)
5.2.1 When convenient, such as in conjunction with occasional glass replacement, or when access is available, Level 1;
5.2.2 Immediately after installation of a new system, Level 2;
5.2.3 Just before expiration of the warranty period, Level 2;
5.2.4 Between 1 and 2 years after substantial completion, Level 1;
5.2.5 After 5 years, Level 1;
5.2.6 After 10 years, Level 2;
5.2.7 After 15 years, Level 1 (if Level 2 was performed as recommended after 10 years); and
5.2.8 After 20 years, and each successive 10 years, Level 2.
6. Symptoms of Problems With SSG
6.1 Whether due to original construction mistakes or latent defects, SSG installations sometimes exhibit distress. The following
list summarizes conditions that may indicate poor original construction or a subsequent failure of the structural sealant, and
therefore require evaluation. This list may not be all-inclusive.
6.1.1 Glass breakage from an unknown cause—There are numerous potential causes of spontaneous glass breakage; if the cause
is unknown, then it should be investigated prior to glass replacement whether an SSG defect contributed to the failure.
6.1.2 Air or water infiltration—If air or water migrates through or to the structural sealant joint, then it must also have lost its
structural function—at least for part of its length. Symptoms of air or water leakage include:
6.1.2.1 Visible accumulation of liquid water during or following storms;
6.1.2.2 Wet insulation;
C1394 − 20
6.1.2.3 Organic growth;
6.1.2.4 Water stains or salt deposits;
6.1.2.5 Audible rattle or whistle;
6.1.2.6 Discoloration of laminated glazing;
6.1.2.7 Condensation or frost on glazing;
6.1.2.8 Fogging of insulated glass units;
6.1.2.9 Opacifier failure on spandrel or other glass—Moisture is a factor in the failure of some opacifiers, and may indicate
water infiltration; and
6.1.2.10 Visible sealant failures— Sealant failures may be observed from inside or outside, depending on the design, and may
involve the weather-seal joint as well as the structural joint. Visible manifestations of sealant fa
...