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P. 06 GE - Advanced Materials
SilPruf* SCS2000 silcone sealant & adhesive
Joint Designs and Dimensions - WEATHERSEALING
(continued)
Butt Jointing - A thin installation of silicone sealant can better
accommodate more movement than a deep installation, as the
deeper bead will result in additional stress being imposed on both
the sealant and the bonding surfaces during joint movement.
Figure 1 illustrates the general guidelines for installation of SilPruf
SCS2000 sealant & adhesive into a typical butt joint configuration
of widths up to 2”.
1.) The recommended sealant profile is an hourglass shape with the
depth of the sealant over the crown of the backer rod to be no
thinner than
1
/8” and no thicker than
3
/8”, and
2.) A minimum of
1
/4” of adhesive bonding contact must be made
to all surfaces to which the sealant is intended to adhere.
When used in joints exceeding 2” in width:
3.) The recommended sealant profile is an hourglass shape with the
depth of the sealant over the crown of the backer rod to be no
thinner than
1
/4” and no thicker than
3
/8”, and
4.) A minimum of
3
/8” of adhesive bonding contact must be made
to all surfaces to which the sealant is intended to adhere.
Figure 1
Non-gassing polyethylene, polyolefin or polyurethane foam rod is
the recommended back-up material for use with SilPruf SCS2000
sealant & adhesive. If the joint is too shallow to allow foam rod, use
a polyethylene tape (as a bond breaker to eliminate three-sided
adhesion). On EIFS and porous substrate applications, a closed cell
backer rod is recommended (open cell backer materials absorb and
hold water which can affect long-term sealant adhesion on these
materials). Backer rod should be 25-50% greater (confirm with
manufacturer of backer rod as to type selected) than the width of
the joint, thereby providing continuous pressure against the joint
walls, and expanding and contracting with the joint movement
without pushing the sealant out of the joint during the compression
cycle or falling away during the extension cycle. Rubber backup
materials may stain the sealant and are not recommended, unless
tested and verified for compatibility.
Joint Designs and Dimensions -
STRUCTURAL GLAZING
• Silicone contact width and thickness (see Figure 2) will vary by
project with the design wind load and glass size.
• Contact Width can be calculated using the following formula:
[Design Wind Load (PSF) x Longest Short Span of Glass or Panel
(Ft.)] divided by 480.
• A minimum sealant thickness of
1
/4” (7mm) between substrates
is required to accommodate thermal expansion and contrac-
tion (see Figure 3) of most systems and should be used in order
to assure that sealant can be injected into the structural cavity
obtaining full contact with both the glass and metal surfaces
while remaining free of air voids. Greater joint thickness may
be required to accommodate movement in some larger-sized
SSG systems. GE - Silicones can be contacted to assist in deter-
mination of proper joint thickness to accommodate expected
movement in structurally glazed applications.
The following materials are required to be submitted to
GE - Silicones to receive suggestions for
the use of SilPruf SCS2000 sealant & adhesive.
• Architectural and shop drawings for review and comment.
• Design wind load requirement(s) for project.
• Glass or panel sizes.
• Production samples of metal, glass, gaskets, spacers and setting
blocks with type and manufacturer identified.
• Specification and/or identification of paint or finish to which
SilPruf SCS2000 sealant & adhesive is intended to adhere
(i.e., 215-R1 anodized or if paint; manufacturer, finish system
and ID#).
Joint Backer Materials
Backer materials, typically backer rod, provide the following
benefits to aide in the correct application of SilPruf SCS2000
sealant & adhesive.
1.) To control and provide the desired sealant depth.
2.) Create a formed joint cavity that allows for the desired
hourglass sealant shape.
3.) Provide a firm backup which helps attain full wetting of the
substrates when the sealant is tooled.
4.) Act as a bond breaker to eliminate adhesion on the backside of
a joint (three-sided adhesion).
1/4'' MINIMUM
ADHESION
CONTACT
DEPTH OVER
CROWN OF
BACKER 1/8'' MIN
TO 3/8'' MAX
JOINT WIDTH