---
catalog: WEB-S3
catalog_name: Sealants & Supplies
page: 21
sku_count: 0
generated_at: "2026-05-21T23:30:08Z"
---

# Sealants & Supplies -- Page 21

## Page Content

FHC SEALANTS AND SUPPLIES
SECTION 4
Bulk Quantities Available
Click to Chat With Us
WS17
Backer Rod
Visit fhc-usa.com to search for
Enter the Item Number or scan QR code with  
your smartphone for complete product details
FHC Backer Rod 
FHC Backer Rod Guidelines for 
Properly Moving Dynamic Joints: DO’s and DON’Ts
Prevents Adhesions on Three Sides 
The sealants inability to bond with the joint’s underside will 
increase movements (Figure 2).
Control the Sealants Bead Depth 
The sealant bead conforms to the manufacturer’s design recommendations,  
enhancing the sealant’s capacity for movement (Figure 2)
Provides Resistance to Tool Against 
When tooled, the sealant is pressed against the backer rod, ensuring optimal 
adhesion to the joint’s side walls (Figure 3). To achieve this, the backer rod 
must be intentionally oversized, ensuring a secure fit within the joint (Figure 4).
The silicone weather 
seal bead hovers 
above the backer rod, 
enabling maximum 
movement.
To ensure uniform 
strength and 
adhesion along 
the bond line, 
the sealant is 
pressed firmly and 
evenly against the 
sidewalls using a 
spatula tool.
Ensure that the minimum 
A to B ratio is 2:1.
A and C dimensions 
must not be less than 
1/4".
The joint surface should 
have a concave tooling.
It is recommended that 
dimension B does not 
exceed 3/8".
A deep sealant bead 
hinders flexibility and 
movement.
Excessive sealant depth 
leads to slower curing.
B dimension exceeds 
the suggested 3/8" 
maximum.
The silicone 
weather seal bead 
remains immobile 
as it is adhered to 
the joint’s bottom.
Uneven gaps 
between the 
sealant and the 
wall result in an 
irregular joint, 
leading to weak 
areas in the 
bond line that 
are prone to 
failure under 
stress.
DO
DON'T
C
C
A
A
Backer Rod
No  
Backing 
Material
Backer Rod
Silicone 
Weather-Seal 
Sealant
Glass
Silicone
Structural
Adhesive
Structural
Spacer
Structural
Spacer
Backer
Rod
No Backer 
Rod
Mullion
Mullion
Open Cell Backer Rod
Sealant
Sealant
B
B
Sealant
Sealant
FIGURE 1:
Regulates the 
Sealant Bead Depth
FIGURE 2:
Prevents adhesion on 
three sides.
FIGURE 3:
Offers resistance 
when using a tool.
FIGURE 4:
An oversized 
rod keeps 
things in 
position.
RECOMMENDED BACKER ROD DIAMETER SIZES
JOINT WIDTH
FHC CLOSED CELL
FHC OPEN CELL
3/16"
1/4"
---
1/4"
3/8"
---
3/8"
1/2"
5/8"
1/2"
5/8"
7/8"
5/8"
3/4"
1-1/8"
3/4"
1"
1-1/8"
1"
1-1/4"
1-1/2
1-1/4"
1-1/2"
2"
1-1/2"
2"
---
Silicone 
Weather-Seal 
Sealant
Glass
Glass
Glass
Sealant 
Spatula
Silicone
Structural
Adhesive
FRAMELESS HARDWARE COMPANY LLC
2323 Firestone Blvd. South Gate, CA 90280 
Toll Free: (888) 295-4531  |  Direct: (323) 968-2031
Fax: (323) 336-8307  | fhc-usa.com