Member Types

The member type you want to select will depend on the structural system into which the member is being framed.

Floor systems have the following member type options:

  • Joist: A structural member supported at each end, and sometimes at intermediate locations, by walls, beams or headers. Joists are used horizontally as a support for a floor frame system. Joists are typically installed parallel to each other and spaced at equal intervals.
  • Flush Beam: The alignment of the top of a horizontal member with the top of the joists and other flush beams; generally, bearing occurs with the use of hangers.
  • Drop Beam: The alignment of the bottom of joists, flush beams, and other framing components with the top of a beam.  The joists and flush beams find bearing on top of the drop beam.

Roof systems have the following member type options. All of these member types may be sloped, i.e. one end can be higher than the other. This is called member pitch and it is measured in units of vertical rise per 12 units of horizontal displacement:

  • Roof joist: a structural roof member also known as rafter. Joists are typically installed parallel to each other and spaced at equal intervals and carry roof sheathing.

  • Flush beam: a roof load carrying member whose top is aligned with the top of roof joists and other flush beams which usually attach to it through the use of hangers.

  • Drop beam: a roof load carrying member that supports the roof structure above by having that roof structure bear only on its top face.

  • Hip/Valley beam: a flush beam, in which spans, loads, and the member slope are automatically calculated from basic inputs which were entered on the Roof Geometry tab.by either Closedtrimmers or Closedplates.

Ceiling systems have the following member type options:

  • Attic Joist: A structural member supported at each end, and sometimes at intermediate locations, by walls or beams. Attic joists are primarily used to provide support to the ceiling and any attic or partial floor above the ceiling. Attic joists are only intended to support vertical loads currently, tension loads are not available for input or design.

Wall systems have the following member type options:

  • Wall Header: A wall header embedded in a wall has two bottom support options to choose from:

Trimmers: The header bears on a trimmer and the bearing capacity parallel to the grain of the supporting trimmer material is considered when analyzing the header's reaction capacity and required bearing length.

Plates: The header bears on a wooden plate and the bearing capacity perpendicular to the grain of the supporting plate material is considered when analyzing the header's reaction capacity and the required bearing length.

The software compares the bearing capacity perpendicular to the grain of the header to the bearing capacity of the support below and picks the lower capacity as the controlling value for reaction capacity and the required bearing length.

  • Stud: Studs are vertical members capable of simultaneously carrying a compressive axial load and a wind lateral load on one side. They are considered repetitive members that are part of a wall system. "Repetitive member" refers to the fact that studs share their loading with adjacent studs that are part of the same wall system that carries and distributes wind pressures.
  • Wall Column: Wall columns are vertical members capable of simultaneously carrying a compressive axial load and a wind lateral load on one side, but they are not considered repetitive members so they don’t share their load with any other part of the wall system that carries and distributes wind pressures. A good example of a wall column would be the trimmers flanking a wall opening.

  • Wind Sill (NBCC only): The Wind Sill member is the lateral load resistance member(s) within an opening assembly. This member type does not typically support vertical loads for the opening assembly and is expected to be fully braced to resist buckling against lateral loads. Self-weight is not considered in the design of this member type.

Free Standing Posts are separate; they are not part of floor, wall, or roof systems:

  • Free Standing Post: Posts are vertical members capable of carrying a compressive axial load.  They are not considered repetitive members so they are expected to carry the full axial load by themselves. Posts don't carry wind lateral loads because they don't belong in wall system that carry and distribute wind pressures.

The software compares the bearing capacity perpendicular to the grain of the header to the bearing capacity of the support below and picks the lower capacity as the controlling value for reaction capacity and the required bearing length.