Platform Frame:

  • Platform framing is now the standard building method, though balloon frame is still used on tall walls or rake walls.

Platform Frame:

  1. A floor platform is built
  2. Load-bearing walls are erected upon the platform
  3. A second floor platform is built on top of the walls
  4. The second floor walls are built upon this second platform
  5. The attic and roof are then built upon this second set of walls

Platform Frame Advantages:

  • It uses short, easily handled lengths of lumber
  • Vertical hollow spaces are automatically fire-stopped by second floor platform
  • Platforms are convenient working surfaces for carpenters

Platform Frame Disadvantages:

  • Each platform constitutes a thick later of wood who’s grain runs horizontally
  • This can lead to large vertical shrinkage, which can cause problems with both the interior and exterior (finish) surfaces)

Platform Frame:

  • Usually made from nominal 2-inch members (Which means they are actually how big?)
  • Delivered to the site in nearest 2 foot increment of length
  • Cut to precise size on site

Platform Frame:

  • Each plane of the structure is made by aligning framing lumber parallel to one another at specified intervals (usually 16″  on center (O.C.) or 24″ O.C.)
  • After layout, they are nailed to crosspieces to maintain spacing and flatness
    • For floors this crosspiece is a rim joist
    • For walls these crosspieces are top and bottom plates
    • For roofs these crosspieces are typically the ridge board or ridge beam and the top plate of the wall below (with blocking)

Platform Frame:

  • These parallel pieces of lumber and their crosspieces are covered with sheathing (a facing layer of boards or panels that going and stabilize the pieces into a single structural unit).
    • Note:  There are also structural walls with specifically rated sheathing attached using specific nails (and nailing patterns).  These walls are called “shear walls” and are generally identified on the structural drawings.