What material should be placed into gaps greater than 1/2 inch before applying caulk?

The appropriate material to place into gaps greater than 1/2 inch before applying caulk is foam backer rod. When sealing larger gaps, the backer rod serves several critical functions. It provides a backstop for the caulk, which helps to control the depth of the material applied. This depth control is crucial because it affects the elasticity and effectiveness of the caulk. Caulking too deep can lead to poor adhesion and the potential for cracking or other failure modes in the caulk over time.

Additionally, the foam backer rod is flexible and compressible, allowing for movement in the joint without compromising the seal. It also prevents the caulk from sinking into the gap, ensuring that a sufficient bead of sealant remains on the surface for optimal performance. When prepared correctly, the combination of the foam backer rod and caulk provides a durable, weather-resistant seal that maintains its integrity over time.

Other materials mentioned, such as wood shims, metal rods, or plastic strips, do not offer the same beneficial properties in this context. Wood shims can absorb moisture and may lead to decay, metal rods may rust or corrode, and plastic strips may not provide a proper backstop for the caulking material. Therefore