What is the difference between open cell & closed cell backer rod and where is each most effective?
Open cell is softer and more “spongy” Advantages: it will fit into tight places and “cling” to the joint better. Disadvantages: if water does leak behind the caulking, the backer-rod will soak the moisture up like a sponge rather than helping to seal the joint off. Closed cell is firmer and not nearly as porous. Advantages: It helps seal the joint off better if water leaks through the caulking and remains firm even in contact with moisture. Disadvantages: It is harder to “stuff” into tight or uneven spots and get it to “cling” and conform to the space it is in.
