Best Materials Roofing Supplies


Log-In   Log-Out
 Shopping Cart:
  0   Items  In Cart
 Total: $0.00
   Hardware & LPG  
   Metal Goods  
   Paint Supplies  
   Pipe Flashings  
   Roof Coatings  
   Roof Hatch/Vent  
   Roof Repair  
   Roof Tiles  
   Safety Products  
   Snow Guards  
   Support Systems  
   Tool Accessories  
   Tools & Equip.  
   TPO & PVC  
Shop With

Backer Rod ProductsBacker Rod

We stock Backer Rod in all types and sizes. We also provide related sealants. We carry Soft Cell, Closed Cell, Open Cell, Hot-Rod Hot-Pour and D-Shaped Backer Rod. We have backer rod (backstop / bond breaker), designed to work with all popular sealants including NP1 Polyurethane, Novalink Polyether, M1, Duralink, glazing sealants and self leveling sealants like Novalink SL or SL1 & SL2, as well as butyls, polyurethane, silicones, tri-polymers, polysulfide, epoxy, acrylic, etc. The "Hot-Rod XL" Hot-Pour and "Open" celled backer rods are used with hot applied products. Expanding foam sealant tape for sealing and metal roof closure is also available. Product Selection Guide is Here.


Backer Rod is an easy to compress rope-like celled polypropylene / polyolefin based foam. It is inserted into a clean joint at the required depth before adding caulk / sealant. Backer Rod creates an even depth and supports (back stops) the sealant / caulk allowing it to form the proper shape (about 2x as wide as deep) and also prevents 3 sided adhesion (bond breaker). It is especially important to use it with Self Leveling Expansion Joint Sealants. Very large and Soft Backer Rods are also used for filling gaps and for sealing in general construction.


Instructions for placing and applying Backer Rod.


Size Selection: Select a backer-rod diameter that is about 30% larger than the nominal width of the joint (but not less than 10% of the largest gap).


Material: Closed Cell Backer Rod is the least expensive. It can be used for either vertical or horizontal joints, and on-grade (ground). Soft Cell is more adaptable to irregular joint widths (it will easily compress up to 70%) and commonly used in vertical tilt-wall construction. Soft Cell is not used on-grade. Hot-Rod is used on-grade and is compatible with hot-pour and chemical sealants. Open Cell is compatible with hot-pour and is resistant to gas, oil and most solvents, but is more expensive. It reduces bubbles and out-gassing. It can also enables quicker cures in some joint designs.

Questions? Email
Or call 1-800-474-7570 / 602-272-8128
You'll get a prompt response !
Backer Rod Pricing & Ordering:  Click links below to get cost, detailed information and to order products. Freight can be estimated by adding items to cart and pressing ESTIMATE SHIPPING button. We have special freight for large orders and multiple boxes. Email us for a quote. Backer Rod Shipping Notes.

Backer Rod By-The-Foot (all types).

 Lowest cost. For ground or vertical. Color may be medium charcoal OR gray, and is not selectable. 3-6 inch may be white. Product Data Sheet

Joint Width    
CLOSED CELL Backer Rod Size (all)
  1/16 - 3/16"      1/4"  <-click for prices & specs
  3/16 - 1/4"        3/8"
  1/4 - 3/8"          1/2"
  5/16 - 1/2"        5/8"
  7/16 - 5/8"        3/4"5 or 6" CLOSED CELL BACKER ROD
  1/2 - 3/4"          7/8"
  11/16" - 7/8"     1 "
  13/16 - 1"         1-1/4"
  1 to 1-1/4"        1-1/2"
  1-3/8 to 1-3/4"  2"
  1-3/4 to 2-1/8"  2-1/2"
  2 to 2-5/8"        3"
  2-3/4 to 3-1/2"  4"
  3-1/2 to 4-1/2"  5"
  4-1/2 to 5-1/2"  6"
soft backer rod close view
SOFT CELL Backer-RodFor more irregular joints, on tilt-wall / vertical joints, and to fill large construction gaps. Easily compressed. Color may be light or dark gray, and is not selectable Product Data Sheet
Joint Width*    SOFT CELL Backer Rod Size
  1/16 - 3/16"      use closed cell --> 1/4" 
  1/8 - 1/4"          3/8 <-- click link for pricing & specs1-1/2" BACKER ROD, SOFT (6 FEET) - 1-1/2" DIAMETER POLY BACKER ROD, SOFT, CLOSED CELLED SKIN, 6
  5/16 - 1/2"        5/8
  7/16 - 3/4"        7/8
  5/8 - 7/8"          1-1/8
  7/8 - 1-1/4"       1-1/2
  1-1/8 - 1-1/2"    2
  1-1/2 -  2          2-1/2
  1-3/4 - 2-1/2"    3
  2-1/4 - 3-1/2"    4
* SOFT backer rod is highly compressible and can be easily used at widths as low as 40% of product diameter (lower in small sizes). CLOSED CELL product can be used in all applications where SOFT is specified.
HOT-ROD XL Backer Rod: Chemically cross-linked closed cell. High-Temperature resistant to 410F. For hot-pour, rubber-asphalt, and thermo-plastic sealants. Resistant to gas, oil and most solvents. Commonly used in roadways, runways, airplane hangers.
Product Data Sheet
Hot Rod Backer Rod, Cross Linked High Temperature
Joint Width
  3/16 - 1/4"        3/8"<-- click for pricing & specs
  1/4 - 3/8"          1/2"
  3/8 - 1/2"          5/8"
  7/16 - 5/8"         3/4"
  9/16 - 3/4"         7/8"
  11/16" - 7/8"      1"
  13/16 to 1"        1-1/4"
  1 to 1-1/4"        1-1/2"
  1-1/4 to 1-1/2"    2"

OPEN CELL Foam Backer Rod: For hot pour where out-gassing and bubbling is a problem, or where quicker curing is needed (it enables 2-sided air exposure). Open cell foam is enable air to reach both sides of joint. Its VERY soft and compressible. Resistant to gas, oil and most solvents. For Hot Pour applications, generally the joint is thicker and closer to 1:1 size. Small joints should have at least 3mm (.12" compression). Available in black or yellow color.
Product Data Sheet or Metric Open Cell Foam Rod
Joint Width      OPEN CELL Backer Rod (all)
  1/8" - 1/4"         3/8" or 9mm <-- click
  5/16" - 7/16"      5/8" (15mm)
  7/16" - 5/8"       7/8" (22mm)
  9/16" - 7/8"       1-1/8" (28mm)
  3/4" - 1-1/4"      1-1/2" 38mm)
  1-1/8" - 1-1/2"     2" (50mm)

D-Shaped Backer Rod 1/2 width D-Shaped Backer Rod (= 1/2 size of the above yellow rod, Half-Rod) in yellow open foam material. Ideal for log-homes and tight-fitting, very shallow or V-shaped joints.
  7/8" x 1650 feet  <-- click link for pricing & specs
  1-1/8" x 1100 feet
  1-1/2" x 500 feet
  2" x 400 feet
Product Data Sheets:
  Closed Cell Backer Rod (ground or wall) Other
  High Temp, Cross Linked, Closed Cell (hot pour, lower cost)
  Open Cell Backer Rod or Metric Open Cell Foam Rod (for lowest out-gassing,
    hot pour, most compression, resistant to gas, oil and most solvents)
  Soft Cell Backer Rod (wall applications / large gap variation)All Kinds of Backer Rod Insertion Tools and Tool Kits
MSDS Sheets:
  Closed Cell and Closed Cell
  High Temp, Cross Linked, Closed Cell
  Open Cell Backer Rod
  Soft Cell Backer Rod

Related Backer Rod Products
  Backer Rod Insertion Tools
  Caulking Guns (Quality caulking guns at great prices).
  Complete Information on Sealants
  Diamond Blades (for cleaning, grinding, sawing, crack chasing)
  Expansion Joint Expansion joint products includes covers & seals for
    roof-to-wall expansion joints, curb mount / curb flange expansion joints,
    corner and crossover expansion joint covers, and straight flange
    expansion joint covers.
  Primers for sealants
Sealant  Products By Family Type:
  Expansion Joint Sealants (SL-1, SL-2 Self Leveling sealants)
  Exterior Grade Sealants (NP-1, TX-1, Duralink, Novalink, etc)
  High Performance Sealants (M-1, Sonolastic 150, Ultra)
  Metal Roof & Siding Sealants (Duralink, etc)
  Quick Cure, High Strength & Low Temp Cure Sealants (SB-1800 etc)
  Structural Adhesive Sealants (Clear 25, M-1, SB-190, Ultra)
  Window & Glass-Roof Sealants (Clear 25, Sonolastic 150, M-1, Ultra)


Removing Old Joint Sealants, Cut-Out Tools


Placing Backer Rod:  (photo courtesy ITP)

Backer Rod Placement

More Placement & Joint Illustrations:

   Concrete Drive / Garage Expansion Joint Drawing

   Concrete Drive / Garage Control Joint Drawing

   Other Design Ideas for Many Types of Interfaces (see sections 4 to 14)

Joint Design (typical specification):
"Design and install all joint applications per ASTM and SWRI recommendations and guidelines. Joints shall be designed with a depth to width ratio of 1:2 (joint depth one-half the width). It is recommended that the joint shall be no less then ¼ inch wide by ¼ deep (6 mm x 6 mm). The maximum depth of sealant shall be 1/2 inch (13 mm). The maximum width is 2" (certain materials; some are limited to 1"). Control the depth of the sealant by using a backer rod that is 25% larger then the joint opening at 75F temperature. Where the joint configuration will not permit a backer rod, it is recommended that an alternative bond breaker be used. Prevention of three-point adhesion is necessary through the use of a backer rod or bond breaker tape to ensure proper joint movement and a long lasting weatherproof seal." Guide to Joint Designs (see sections 4-14).
Applying Backer-Rod:
Backer Rod Insertion Tools
When working on concrete expansion joints, backer rod is used together with SL1 & SL2 self-leveling sealants.
1. Joint or opening should be clean and dry and free of all contaminates, loose materials, dry, and free of water or frost.
2. To install, compress backer-rod into the joint before sealants are applied. Install backer-rod using a blunt tool or a plain faced roller.
3. Force the rod to the depth recommended by sealant manufacturer, (typically about 1/2 of joint width measured at the crown of the backer rod). A template or roller gauge may be used to control the depth at which the rod is placed.

4. Don't 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. Use a backer-rod roller or smooth tool to set backer rod to proper depth.
5. IMPORTANT NOTE FOR SELF-LEVELING SEALANT APPLICATIONS: All Backer Rod sides, joints and end areas must be completely sealed against a joint surface, otherwise Self Leveling sealants WILL run out of any gaps. Use heavy masking tape on sidewalk edges.
1. If joint priming is needed, follow suggestions for joint-sealant application as directed by sealant manufacturer.
2. Where necessary, primer should be applied only to the edges of the joint surface and allowed to dry before Backer-Rod is placed. DO NOT prime Backer-Rod.
How Much Sealant? Link to Calculator
Applying Sealants:
1. Where priming of the surface material is necessary, primer should be applied only to the sides of the joint surfaces and allowed to dry tack-free before the Backer-Rod is placed. DO NOT prime the Backer-Rod. Many primers ARE STAINING, be careful where they are applied.
2. Follow suggestions for joint-sealant application as directed by the sealant manufacturer.
3. As needed, tool to desired shape using a caulking tool or old spoon. Hint: For polyurethanes, wet the tool regularly with water or toluene to enable a smooth surface. Soapy water is not recommended as some soaps can interfere with joint bonds.
4. Most products need 24 hours minimum cure before applying any type of over-coating. Follow the manufacturers recommended cures.
 HINT: For those not who are not professional applicators, use masking tape on surfaces where you do not want sealants. Sealants are very difficult to remove from unwanted areas.
Soft Backer Rod vs. Closed Celled Backer Rod:
  • Soft Cell is generally used in vertical applications, above ground, or where joints are more irregular, and to fill air-gap spaces in general construction.
  • Closed celled is generally used for ground level applications and high moisture environments. It can be used anywhere the soft-celled is used.
  • Soft celled compresses up to 90% in smaller sizes and 50% in larger sizes.
  • Closed celled compresses up to 50% in smaller sizes and 30% in larger sizes.
  • Either can be used with Self-leveling sealants and Vertical Joint Sealants.
  • Both closed and soft cell are Polyethylene based (polyolefin) foam.
  • Both have color variation in the manufacturing process or suppliers.
Open Cell ("Denver Foam") Backer Rod:
  • Open-cell soft backer rod is highly compressive. It serves as a backing for caulking, sealants and all types of hot pour, chemical sealant and cold sealant products.
  • It is yellow in color, odorless and chemically inert, made from Polyurethane.
  • Open cell backer "Denver Foam" rod can take up to 500F during hot applications and is compatible with all types of ASTM D3405, D1956 and C1330 hot pour and chemically cured sealants.
  • Open cell allows air to reach sealant from BOTH sides during cure, providing a bubble free, faster, more uniform cure.
  • Open cell construction eliminates out-gassing and cold flow problems sometimes  associated with certain materials.
  • Open cell backer rod can also be "saturated" with sealant and used to "carry" sealant to difficult-to-reach repair areas and to create underwater "plugs" (normally it will not absorb sealant without "working it" in).
Backer Rod Selection Guide:
Meets ASTM C1330
Meets ASTM D5249
Meets ASTM C717
Cold Applied Sealant Use
Hot Pour Sealant Use
Round Foam Rod
Non-absorbing Skin
Prevents Bubbling
Closed Cell
ASTM C1330 Type B
ASTM C1330 Type C
ASTM C1330 Type O
ASTM D5249 Type 1
ASTM D5249 Type II (2)
ASTM D5249 Type III (3)

(ASTM D5249 type II is a flexible closed cell foam sheet)


CLOSED & SOFT Cell Backer Rod:
  • Density: 2.0 lbs/ft3 ASTM D-1622
  • Tensile Strength: 50 lbs/sq inch ASTM D-1623
  • Moisture Absorption: Less than 1% by volume ASTM C-1083
  • Temperature Service Range: -90ºF to +210ºF
  • Compression Deflection, 5 PSI @ 25%, ASTM D-1621 (Closed Cell)
  • Compression Deflection, 5 PSI @ 50%, ASTM D-1621 (Soft Cell)
  • Water Absorption: 0.02% by volume, ASTM-C-509 (Closed Cell)
  • Water Absorption: 0.05% by volume, ASTM-C-509 (Soft Cell)
  • R-Value = 3 per inch of thickness.
  • Thermal Conductivity (W/M per.deg C) = 0.036
HOT ROD XL, Hot Pour Backer Rod:
  • Density: 2.0 lbs/ft3 ASTM D-1622
  • Tensile Strength: 31.4 lbs/sq inch ASTM D-1623
  • Temperature Range: -90ºF to +410ºF
  • Compression Deflection, 4.7 PSI @ 25%, ASTM D-1621 (Closed Cell)
  • Water Absorption: 0.02% by volume, ASTM-C-509
  • Water Absorption: 0.03 gm/cc, ASTM-C-1016
OPEN Cell Backer Rod:
  • Density: 1.7 lbs/ft3 ASTM D 1622
  • Tensile: 25 lbs/sq inch ASTM D 1623
  • Moisture Absorption: .024% by volume ASTM C 509
  • Out Gassing: None Open Cell
  • Temperature Service Range: -60ºF to +400ºF
    U.S. Department of Commerce National Institute of Standards
  • R-Value = 3 per inch of thickness.
  • Thermal Conductivity (W/M. ºC) = 0.036
  • Auto Ignition: 700-800ºF
  • Elongation: 90% ASTM D 3574
  • Air Flow: 90% ASTM D 3574
  • Compression set 5% or less (after 80% compression for 30 days) ASTM D 3574

Our Soft, Closed Celled and Hot Rod backer rods are all polyolefin based. A polyolefin is a polymer produced from a simple olefin (also called an alkene with the general formula CnH2n) as a monomer. For example, polyethylene is the polyolefin produced by polymerizing the olefin ethylene Polypropylene is another common polyolefin which is made from the olefin propylene.


SOFT Backer Rod & Construction Uses: Soft Backer Rod for residential construction is also commonly used to seal air gaps around wall or joint cavities, between pre-hung doors and windows and rough openings in wood frame homes. The low compression deflection and high compression recovery of these products will not bow windows or door jambs and adapts to seasonal joint movement. Specific uses for Soft Backer Rod includes log homes, marriage joints, sealing at attic access openings, casement window joints, some dry wall applications, wall to wall joints, wall to floor joints, and roof to wall joints, and around doors and windows in wood frame structures.


Compatibility: Our our backer rod products are an inert composition and therefore compatible with all known cold applied sealants including butyl, polysulfide, vinyl acetates, PVA, acrylics, polyurethanes, tri-polymers and silicones. They are chemically inert and will resist oil, gasoline and most other solvents. These materials will not stain nor adhere to sealant materials and are non-exuding. For HOT pour and chemical sealants, use Hot-Rod or the Open Cell Foam. If bubbling / gassing is a problem, Open Cell Foam is best. More Information can be found in the Technical Data Sheets.


EIFS Construction and Joint Design: See the EIFS Guide for details.  Trouble-free EIFS application is accomplished by forming a 1/2" to 3/4" sealant gap wherever EIFS meets a non-EIFS material, such as roofing, trim, or doors and windows, according to the EIMA EIFS Guide. The correct gap makes it possible to finish the exposed edges of the expanded polystyrene, which should be wrapped with reinforcing mesh before the EPS is secured to the sheathing with a waterproofing application of base coat. Then the rest of the finish goes on. Finally, the gap is filled with soft or closed-cell backer rod and a bead of compatible sealant. Novalink Polyether Sealant is an excellent sealant for this applications. Textured Sealants are also available which cure textured to look stucco-like.

EIFS Joint Design, Typical
















Shipping Backer Rod: Backer Rod although inexpensive, can be expensive to ship. This is because of the large volume of space it takes in boxes. Dimensional weight applies. More information is here: UPS Dimensional Weight and Oversized Packages


Show More Popular Products and Suppliers:

Popular Products and Pages:

Access Panels Adhesives, Backer Rod, Brads, Butyl Rubber, Caulk & Sealants, Caulk Guns, Caulking Gun Accessories, Caulk Gun, Bulk, Chem Curbs, Chinking, Coil Roofing Nails, Concrete Anchors, Concrete Products, Concrete Repair, Concrete Stain & Sealer, Confined Space Rescue, Deck Coatings, Deck Hardware, Diamond Saw Blades, Drains, Drains-Balcony>Drain-Balcony, Drain Downspouts / Nozzles, Roof Drain Domes, Drains New-Roof, Drains-Retrofit/Re-roof, Electric Hot Air Welders, Electric Service Flashings, EPDM Accessories, Eternabond, Expansion Joints, Fall Protection Kits, Fasteners, Fire Stopping Vents, Flashing Tape, Foam Roofing, Gas & Safety Cans, Generators, Grouts, Hidden, Deck Fasteners, Hot Dipped Roofing Nails, Hot Tar Kettles, Houseboat Roof/Deck Repair, Knowledgebase, Log Home Products, Lead Pipe Flashings, Lead Sheet, Magnetic Hammers, Metal Roofing, Miami-Dade Nails, Mortars, Narrow Crown Stainless, Staples, NP1, Polyurethane Foam, Pipe Flashings, Pipe Supports, Power Tools & Accessories, Propane Regulators, Propane Torches, PVC Roofing, PVC Roofing, Retrofit Pipe Flashings, Rex Synfelt, Rigging/Lifting Hardware, Rivets, Rivets- Stainless, Roof Anchors, Roof Equipment Hatch, Roof Smoke Vents, Roof Hatch, Roof Leak Repair, Roof Paints & Coatings, Roof Repair Materials, Roof Screws, Roofing Fasteners, Roofing Nails, Rooftop Electrical Flashings, Rope, RV & Trailer Roof Repair, RV Roof Replacement, Safety Rail Systems, Saw Blades, Sealants, Sealing Washers, Snow Guards, Spray Polyurethane Foam, Stinger, Stainless Nails/Fasteners, Tarps, TPO Accessories, Underlayments, Vents, Roof Vents, Video Movies, Waterproofing Products, Window Flashing Tape, Wood Deck Hardware, Zinc Sheet

Popular Suppliers Include:

ACRO, Active Ventilation, AES Epoxies, AES Raptor, AJC, Albion, Alcoa/Marson, All Line, Alpha ProTech, American Sealants, Applied Technologies, ASI Products, Attic Breeze, Aztec Washer, Babcock- Davis, BAK Welders, BASF, Berger, Berry Plastics, Biltrite, Brentwood, Brewer, CEP, Chem Link, Cleasby, CME Manufacturing, CPR, Deks, Dow, Eagle, EagleView, Erin Rope, ES Products, Eternabond, Everhard, Falltech, Flame Engineering, Flashco, Foxy, Franklin / Titebond, Fry Reglet, Greenstreak, GSSI, Guardian, Harpster, HY-C, Interwrap, ITP, ITW, Jaaco, JL Industries, Josam, Karnak, Levis, LionGuard, LSP, Lucas, Luco, Makita, Marathon, Marshalltown, Maze Nails, MB Technology, MEC, MFM, Miro, MM Products, National Nail, Natural Light, Newborn, OMG, Pam Fasteners, Pearl, Polar Blox, Polycoat, Portals Plus, Powers Fasteners, Prime Source, ProTech, Protecto Wrap, Pylex, Quarrix, QuickMount, RHH Foam, Robetex, Roofmaster, RoofTop Products, Senco, SFS Intec, Sievert, Simpson Strong-Tie, Smith, Sno Gem, Solomon, Sonneborn, Steelhead, SunRise Solar, Sunset, Super Anchor, Surebond, Swan Secure, TRA, Trufast, United / Quest, Vulcan, Wade, Watts, Weatherbond, Werner, Western Colloid, Winco, Zurn

Shop with
Peace of Mind!