Band Joist and Sill Plate – Defined. The band joist and sill plate are the set of boards (in wood frame houses), or blocks (in a brick house) that sit on top of the foundation wall and run in a band around the house.Click to see full answer. Moreover, what is the difference between a rim joist and a band joist?A rim joist’s relationship to the joists is similar to what the top or bottom wall plate is to the studs. It is also confusingly called a header (header also refers to other framing components) or rim board. Collectively, the end joists and rim joists are called band joists, especially in regard to deck construction.Also, what is a band board construction? Band boards are treated boards placed on the outside of your home behind your home’s exterior covering that cover the seam where your foundation and sill plate meet. Because band boards come in contact with the sill plate, the foundation and the outdoors, they are especially vulnerable to wood rot. Also to know is, is a rim joist load bearing? The main job of a rim joist, also called a band joist, is to provide lateral support for the joists, to prevent the joists from leaning under the weight of the load-bearing walls resting on them. The rim joist also covers the ends of the joists to cap off the joist cavities, the open spaces between the joists.What is band joist insulation?Band Joist Insulation. The outside ends of these joists and the space between them are covered with a band joist or “header.” This band joist is usually the same size as the floor joists and runs around the entire perimeter of the building.