4 in. Backer Rod, SOFT (6 feet) - 4 inch Diameter Poly Backer Rod, Closed Cell, Soft, Non-Stick Skin. 6 feet/Piece (actual length ~69 inches). Price/Piece. (color is gray or charcoal and is not selectable; 8 sticks per case, select full cases for added discounts; UPS shipment only)
4 in. Backer Rod, SOFT (6 feet)
$20.00 SALE $15.95
(Savings: $4.05)
 Buy 8 or more and pay $14.20 each (save 29.00%) 
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4 inch Diameter Poly Backer Rod, Closed Cell, Soft, Non-Stick Surface Skin. 6 feet/Piece (actual length ~ 69 inches). Price/Each.


  • Shipping leadtime: 1-2 business days.
  • Color can be gray or charcoal and is not selectable.
  • 8 sticks per case, specify full cases for added discounts.
  • UPS shipment only.
  • Carton Packing: 8 pieces/carton, 14 lbs, 17x10.3x74 inch size.


Round poly foam joint filler and backing for sealants. Provides controlled depth for sealants. Compresses easily for accommodating joints of varying widths. Does not stick to sealants. Exceeds ASTM standards for bond breaker materials. Consists of both open and closed cells on the inside with a skin-like outer texture. Non-stick closed cell skin. High moisture resistance. Compatible with all know types of sealants including butyl, polyurethane, silicones, tri-polymer, polysulfide, acrylic, etc.


  • General Purpose Sealant backing
  • Together with Self-leveling sealant
  • Expansion joints
  • Irregular joints
  • Metal and pre-cast panels
  • Around perimeters of door and window frames
  • Coping and glazing joints
  • Log Homes

    Select a backer-rod diameter that is approximately 25% larger than the width of the joint.

    Joint Width  Diameter
    3/16" - 1/4"    3/8"
    3/8" - 1/2"      5/8"
    1/2" - 3/4"      7/8"
    3/4" - 7/8"      1-1/8"
    7/8" - 1-1/4"   1-1/2"
    1-1/4" - 1-1/2"  2"
    2" - 2-1/2"        3"
    2-1/2" - 3"        4"


    1. Joint fillers have three major functions:

  • Controls depth of the sealant in proper relation to joint width.
  • Provides backing against which the sealant is applied, forcing the sealant to the sides of the joint.
  • Prevents 3-sided bonding, ensuring proper function of sealant.
  • 2. To install, compress backer-rod into the joint before sealants are applied. Joint or opening should be clean and dry and free of obstructions. Install backer-rod using a blunt probe or a plain faced roller to force the rod to the desired depth.

    3. Compress to a depth of about 1/2 of the width measured at the crown of the backer rod.

    4. A template or roller gauge may be used to control the depth at which the rod is placed.

    5. Do not stretch, puncture or tear backer-rod during installation but gently force into the joint so that the backer-rod fits tight against the sides of the joint.


    1. Follow suggestions for joint-sealant application as directed by sealant manufacturer.

    2. Where priming of the joint is necessary, primer should be applied only to the joint surfaces and allowed to dry before Backer-Rod is placed. DO NOT prime Backer-Rod.


    Email us at sales@bestmaterials.com or
    Call us at 1-800-474-7570 or 602-272-8128
    You'll get a prompt reply!

    similar product terms: backer rod, soft celled backer rod, chinking, chink backing, caulk backing, sealant backing, sealant support, caulk support, soft cell foam, closed cell foam rod, log home chinking

      Associated Items:  
    4 in. Backer Rod, SOFT (box/54 feet)
    4 inch Diameter Poly Backer Rod, SOFT with Non-Stick Closed Cell Skin. Cut to 6 Foot Pieces. 9 Pieces/Box (54 feet). Price/Box. (color may be gray or charcoal and is not selectable; UPS Shipping only)
    $208.00 $128.45
    Quantity:     Add to Cart

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