ASTM C964-07(2012)
(Guide)Standard Guide for Lock-Strip Gasket Glazing
Standard Guide for Lock-Strip Gasket Glazing
SIGNIFICANCE AND USE
3.1 This guide provides information and guidelines for the design of lock-strip gasket glazing systems. For related standards, see Specifications C542, C716, and C963.
SCOPE
1.1 This guide covers the use of lock-strip gaskets in compliance with Specification C542 in walls of buildings not over 15° from a vertical plane. The prime performance considerations are weathertightness against air and water infiltration, and structural integrity under wind loads. Included are terminology, design considerations, and fabrication tolerances when using lock-strip gaskets in glazing applications.
1.2 The values stated in SI units are to be regarded as the standard. The inch-pound units in parentheses are for information only.
1.3 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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C964 − 07 (Reapproved 2012)
Standard Guide for
Lock-Strip Gasket Glazing
This standard is issued under the fixed designation C964; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope Windows, Doors, Skylights and CurtainWalls by Uniform
Static Air Pressure Difference
1.1 This guide covers the use of lock-strip gaskets in
E331 Test Method for Water Penetration of Exterior
compliance with Specification C542 in walls of buildings not
Windows, Skylights, Doors, and Curtain Walls by Uni-
over 15° from a vertical plane. The prime performance
form Static Air Pressure Difference
considerations are weathertightness against air and water
infiltration, and structural integrity under wind loads. Included
3. Significance and Use
are terminology, design considerations, and fabrication toler-
3.1 This guide provides information and guidelines for the
ances when using lock-strip gaskets in glazing applications.
design of lock-strip gasket glazing systems. For related
1.2 The values stated in SI units are to be regarded as the
standards, see Specifications C542, C716, and C963.
standard. The inch-pound units in parentheses are for informa-
tion only.
4. Comparison to Other Standards
1.3 This standard does not purport to address all of the
4.1 Thecommitteewithjurisdictionoverthisstandardisnot
safety concerns, if any, associated with its use. It is the
aware of any comparable standards published by other orga-
responsibility of the user of this standard to establish appro-
nizations.
priate safety and health practices and determine the applica-
DESIGN CONSIDERATIONS
bility of regulatory limitations prior to use.
5. General
2. Referenced Documents
5.1 Structural integrity and watertightness of a gasket glaz-
2.1 ASTM Standards:
ing system is dependent on interaction of the several compo-
C542 Specification for Lock-Strip Gaskets
nents involved. These systems should be carefully designed
C716 Specification for Installing Lock-Strip Gaskets and
and built.
Infill Glazing Materials
C864 Specification for Dense Elastomeric Compression Seal
6. Components
Gaskets, Setting Blocks, and Spacers
6.1 The major components of lock-strip gasket glazing and
C963 Specification for Packaging, Identification, Shipment,
paneling systems are:
and Storage of Lock-Strip Gaskets
6.1.1 The supporting frame of metal, concrete, or other
C1036 Specification for Flat Glass
structural building materials,
E283 Test Method for Determining Rate of Air Leakage
6.1.2 Lock-strip gasket, serving as an elastomeric mechani-
Through Exterior Windows, Curtain Walls, and Doors
cal seal and as a retainer for panel or glass, and
Under Specified Pressure Differences Across the Speci-
6.1.3 Glass or panel infill.
men
6.1.4 The design of these components and their accessories
E330 Test Method for Structural Performance of Exterior
are interrelated and the total system must be compatible.
7. Supporting Frames
ThisguideisunderthejurisdictionofASTMCommitteeC24onBuildingSeals
and Sealants and is the direct responsibility of Subcommittee C24.73 on Compres-
7.1 Supporting frames are made of many materials, of
sion Seal and Lock Strip Gaskets.
which the more common are aluminum, steel, and concrete.
Current edition approved Dec. 1, 2012. Published December 2012. Originally
7.1.1 Metal—Die marks, ridges, offsets, and scratches in
approved in 1981. Last previous edition approved in 2007 as C964 – 07. DOI:
10.1520/C0964-07R12.
metal frames in contact with the gasket lips that could cause
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
leakage should be avoided. Metal in contact with any part of
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
the gasket should have sharp edges and burrs removed to avoid
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the possibility of damage to the gaskets that could result in
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C964 − 07 (2012)
structural failure through tear propagation. Weathering steel cornerbuttjointsareeliminatedandthegasketlipsmakedirect
frames used in gasket installations should be coated to prevent contact with the concrete frame. With this concept it is
corrosion on the surfaces covered by the gasket to a line not essential to have a continuous smooth surface free of voids or
less than 3.2 mm ( ⁄8 in.) beyond the lip edge when installed. honeycombing for the gasket lips to seal against because water
7.1.2 Concrete—Gasket lips in contact with protrusions, could bypass the gasket lip and enter under it. Also important
crazing, form marks, and offsets on concrete surfaces could is to have a sharp arris at the corners of the concrete frame so
causeleakageandglassbreakageandsuchirregularitiesshould that the corners of the gasket lip can properly contact and seal
be avoided. Concrete frames for lock-strip gaskets should be against the concrete. When plastic reglets are used, joints in
jointless and are more suitable when precast, as the tolerances them could cause leaks unless sealed. When the gasket lips are
and smooth surfaces required are too exacting for cast-in-place in direct contact with the concrete, meticulous casting proce-
concrete. Special forms and meticulous casting procedures are dures and close surveillance are required to assure a proper
required for optimum performance. finish along the contacting surface.
7.1.2.1 Corner Angles—Corner angles in the plane of the 7.1.2.3 Frame Lug—It is difficult to achieve watertightness
glass should be held to 62° tolerance to properly receive the with a gasket gripping the lug of a concrete frame as shown in
gasket lips. See Fig. 1. Fig. 2. Casting the lug to the 0.8-mm (6 ⁄32-in.) tolerance
7.1.2.2 Reglets—It is essential that the recess in the concrete required is unrealistic when dealing with concrete. Also,
be accurately cast so as to properly receive the spline of the casting it without a tapered draft for ease of form removal
gasket. This can be accomplished with a plastic reglet that has results in complicated form work. A tapered draft provides
a removable weakness membrane as shown in Fig. 1. The poor control over gasket lip pressure and results in a reduction
removable membrane maintains the proper recess shape and of pressure when excessive edge clearance permits the gasket
keeps concrete out of the reglet while being cast. The remov- lips to slip to the narrower part of the lug. Unless the gasket
able membrane can beT-shaped, when desirable, with the stem gripping the lug of a concrete frame has enough mass,
projecting from the reglet to provide a more convenient means insufficient lip pressure against the concrete frame and leakage
of attachment to the formwork of the concrete panel. After could result because of the relatively large lug width.
casting, the weakness membrane is easily removed. Plastic 7.1.3 Joints—Ideally, the best type of frame over which to
reglets are available with flanges extending beyond the gasket seat the gasket is one without joints. However, the realities of
lips, providing smooth contact surfaces. An advantage of the construction should be recognized and dealt with. Watertight-
plastic flange is the provision of a smooth rigid surface for ness between the lock-strip gasket and frame depends on
contact with the gasket lip. The plastic flanges are butted unbroken pressurized contact. Joints in metal, unless welded
together at the corners requiring a joint which should be and ground flush and smooth, make this concept difficult to
properly aligned and sealed. The exposed plastic flange should achieve. Members on either side of a butt joint should be
be solidly cast into the concrete without any voids or honey- installed as true to plane as possible. If the design relies upon
combing at the leading edge of the flange because water could sealed metal-to-metal joints, the small void between the gasket
enter the interface between the flange and the concrete into lip and metal should also be sealed with a supplementary
which it is cast.An advantage of the flangeless reglet is that the sealant. A recommended safeguard is to have a built-in
exposedjointbetweentheflangeandtheconcreteaswellasthe drainage system within the frame. In this way, any water
penetrating the frame joints or gasket to frame joints will be
directed back to the outdoors. An aid towards minimizing the
possibility of water penetration between the gasket and frame
at static (fixed, nonmoving) metal joints in single openings
may be seen in Fig. 3. The direction of the joint is horizontal
between the horizontal and vertical members at the top of the
frame, and vertical between the horizontal and vertical mem-
bers at the bottom of the frame.
A Sharp arris (no radius) required
B Nominal angle ± 2° tolerance
C Smooth surface required
D 6.4 mm ( ⁄4 in.) minimum
E Removable weakness membrane
NOTE 1—Insufficient mass at A and relative long distance from B to
F Flange provides smooth surface at lip
lock-strip minimizes potential for adequate lip pressure at B.
FIG. 1 Reglet-type Gasket in Concrete FIG. 2 Gasket Mounting on Concrete Lug
C964 − 07 (2012)
A Hinge H Glass or panel
B Lock-strip I Bite
FIG. 3 Single-opening Metal Frame Joints for Increased Water-
C Lock-strip cavity J Edge clearance
tightness
D Lip (sealing edge) K Frame-to-glass dimension
E Channel recess L Frame lug
F Flange M Frame
7.1.4 Frame-to-Gasket Lips Clearance—Because lip pres-
GWeb
sure is critical in resisting the passage of water, the design of
FIG. 5 Basic H-Type Gasket, its Functional Principles and No-
the supporting frame must allow at least 3.2-mm ( ⁄8-in.)
menclature
clearance between the installed gasket lip and any projecting
flanges or fillets. This allows the lips to exert unrestricted
pressure against the frame as shown in Fig. 4.Where the frame
H-type gaskets are available that accommodate glass, panels,
lug and projecting flange form a fillet, the recommended
and frame lug thicknesses ranging from 1.6 to 32 mm ( ⁄16 to
clearance should not include the convex portion.
1 ⁄4 in.). Gaskets accommodating thicknesses greater than 32
mm (1 ⁄4 in.) are also available. Thick panels should not be
8. Gaskets and Accessories
mounted on relatively thin lugs as the weight of the glass or
8.1 To accommodate the wide variety of glass and panel
panel cannot be supported properly. The best performance can
thicknesses available as well as allow for mounting to various
be expected where the lug thickness equals or exceeds the
types of framing members, a wide variety of gasket cross
thickness of the glass or panel. There are exceptions to this
sections are produced by the extrusion manufacturing process.
recommendation which are dependent upon other factors, such
The technique of extruding varies among the manufacturers,
as lightweight panels, extremely small openings, or situations
and has a limiting factor on the complexity of cross-section
where total performance is not required.Acceptable deviations
designs produced.
require engineering analysis, consultation with the gasket
8.1.1 Gasket Types—Lock-strip gaskets are typically iden-
manufacturer, and testing.
tified by their general cross-section configuration. The most
8.1.1.2 Reglet Type—The reglet-type gasket is a patented
common are H-type and reglet type. Other special and propri-
type whose functional principles and nomenclature are illus-
etary interlocking types have been developed as a result of
trated in Fig. 6. Reglet-type gaskets are designed with a spline
modifications to the basic types, usually because of provisions
for mounting or mating to special framing members. Gasket
sections are generally of two types: the perimeter section and
the muntin section.
8.1.1.1 H-Type—The basic H-type gasket, its installation,
and nomenclature are illustrated in Fig. 5. After the gasket is
installed over the frame and the glass or panel infill installed in
the gasket, the lock-strip, which is of higher durometer, is
forced into a groove in the gasket. A resultant compressive
force is transferred to the lips which apply pressure to the
frame and glass. Sufficient lip pressure against smooth surfaces
creates an effective weathertight seal. A wide selection of
A Hinge H Glass or panel
B Lock-strip I Bite
C Lock-strip cavity J Edge clearance
D Lip (sealing edge) K Frame-to-glass dimension
E Channel recess L Spline
F Flange M Reglet
GWeb
FIG. 6 Reglet-type Gasket, its Functional Principles and Nomen-
FIG. 4 Gasket Mounting Clearance clature
C964 − 07 (2012)
that fits into a reglet. The seal against the frame is accom- water.This may be the case with a corner having square lips on
plishedbyforcingthesplineofthegasketintotheregletsothat the frame side where, because of the longer diagonal distance
the fins on the side of the spline retain the gasket in the reglet to the lock-strip, little or no lip pressure may be obtained at the
and thus hold the sealing lips of the gasket tightly against the apex. It should not be assumed that passage of the lip pressure
frame surface. The seal against the glass or panel is accom- test in Specification C542 provides assurance that the gasket is
plished by the insertion of the lock-strip as with the H-type adequate for resistance to the passage of water. Gasket corner
gasket. Most reglet-type gaskets are designed to fit into a reglet designs having square lip seals are not as common as previ-
3 5 1
that is 19 mm ( ⁄4 in.) deep and 16 mm ( ⁄8 in.) wide. If the ously. Gaskets having approximately 6.4 mm ( ⁄4 in.) radius at
reglet is of lesser depth, the gasket will “bottom-out” and not the external corner lips are now available. With such a design,
provide a proper installation. If the reglet is too wide, the a more uniform edge distance is maintained from the lip edge
gasket will not be held in place properly and thereby provide to the lock-strip as shown in Fig. 8. In this way, lip pressure is
difficult glass or panel installation. If the reglet is too narrow, not generally reduced around the corner as with a square lip
the gasket will be difficult to install. Reglet-type gaskets are because of the appreciably longer moment arm. Generally, the
availablethataccommodateglassorpanelthicknessesfrom1.6 round lip is
...
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