What is a rim joist?

A rim joist, also known as a band joist, is a horizontal board that runs along the edge of a floor system and provides structural support to the joists and subfloor above. It is typically located at the perimeter of a floor system and helps to distribute the weight of the structure evenly.

Rim joists are often used in platform framing construction and are typically made of the same material as the floor joists, such as wood or engineered lumber. They are also commonly used in conjunction with a sill plate to create a stable and secure connection between the foundation and the floor system.

Rim joists play a crucial role in ensuring the stability and strength of a structure, as they help to transfer loads from the walls and floors to the foundation. Properly installing and sealing rim joists can help prevent air and moisture infiltration, which can lead to energy loss and structural damage over time.

Overall, rim joists are an essential component of a floor system and play a key role in supporting the weight of a structure and helping to maintain its integrity.