Professional-Grade Closed-Cell Backer Rod – Precise Depth Control for Sealant Joints Our high-performance closed-cell polyethylene backer rod is engineered for superior joint preparation in construction, glazing, and sealing applications. With its resilient, water-resistant outer skin, this backer rod delivers precise depth control for most cold-applied sealants — eliminating the need for a separate bond breaker. Reliable and Versatile – Compatible with urethane, silicone, acrylic, butyl, polysulfide, latex, and chinking sealants, making it an essential tool for contractors, builders, and DIYers. Perfect for expansion joints, glazing projects, log home chinking, curtain walls, coping joints, isolation joints, parking decks, and more. Built to Last – Chemically inert, stain-resistant, and able to withstand temperatures from -90°F to 190°F. With >90% compression recovery, it maintains shape and performance even under heavy use. Easy Installation – Flexible, lightweight, and quick to install using a blunt tool or roller. Will not adhere to sealants, ensuring clean, professional results every time. Available in multiple diameters and lengths to suit any project, our closed-cell backer rod meets ASTM D5249 Type 3 and ASTM C1330 Type C standards for quality and performance.