The bottom or sole plate, also called simply the sole plate, is the horizontal beam at the bottom of a framed wall. The bottom plate is a support beam that sets on the sub-floor, nailed down into the floor joists. In rare cases where, for some reason a bottom or sole plate cannot be nailed to the floor, an adhesive like Liquid Nails is sometimes used, but only in those situations where nailing isn’t possible. The studding or the uprights of a framed wall are first nailed to the bottom or sole plate.
Lumber Used for a Bottom or Sole Plate
The bottom or sole plate is generally 2X4’s or 2X6’s, upon which the vertical 2X4’s or 2X6’s studs are nailed.
The bottom or sole plate is sometimes connected to the wall studs by using metal straps or clips, ensuring less movement of the studs and a more secure wall. Care should always be taken to see that the piece of lumber used for the bottom or sole plate is straight and not bent. It is also advised never to use green wood for a bottom plate, since it can warp and affect the wall structure.