What is used to fill joints?

• A. Silicone (most common), caulking
• B. Silicone and epoxy grout
• C. Silicone (most common), compound, and modified grout
• D. Epoxy grout and foam filler

Answer: (C)

Joints between panels and around openings need something that can seal out water and air while accommodating movement. Silicone sealant is the most common filler for these joints because it stays flexible over time and adheres well to concrete and other substrates, letting the joint expand and contract without cracking. In addition to silicone, a caulking compound (a flexible filler used in smaller or less demanding joints) is often employed when less movement needs to be accommodated or when a budget option is appropriate. For joints that are filled with grout, a polymer-modified grout provides better adhesion and some elasticity compared to plain grout, making it more resistant to cracking under movement.

Epoxy grout, while very durable and stain-resistant, is rigid and not ideal for joints that experience movement, and foam filler cannot provide a durable, long-term seal for these joints. Therefore, the typical fill options are silicone sealant, caulking compound, and polymer-modified grout.