Wood Framing Lessons

Wall Top and Bottom

• The top plate of each wall is typically formed with a double layer of 2-by-4 lumber lying flat. This double thickness acts as a fire break, to isolate the pockets in the wall between studs in case of combustion. The bottom plate is usually a single thickness. If additional height is required this can be doubled, with the first thickness being bolted to the floor and the top layer fastened to it from the top with nails.

Spacing

• In general all frame spacing is the same. Walls call for studs to be placed 16 inches on center, which means from the center of one stud to the center of the next should be 16 inches. Most tape measures allow for this with special markings that make layout simpler. Joists for floors and ceilings are spaced a little further apart at 24 inches on center. Rafters maintain this 24-inch spacing as well.

Windows and Doors

• Windows and doors are framed similarly with a king stud on the outside of the opening, running from the sill, or bottom plate, to the cap or top plate of the wall. Inside this pair doors feature a jack stud that runs from the sill to just under the door frame header. Windows also have a double stud at the sides, with theirs running from the sub sill up to the header. Headers are made from two thicknesses of 2-by-6 or 2-by-8 lumber on edge, with a piece of 1/2-inch thick plywood sandwiched in between. Sub sills are made from a double horizontal 2-by-4 between the king studs.

Trusses

• Roof framing has been simplified by the invention of the roof truss. This prefab triangular frame features two upper cords, or rafters, that form the peak, a lower horizontal known as a lower cord, or joist and the center is supported by a center vertical known as the king post. Various styles of additional support are used angling off of this center post. These are referred to as webbing. The trusses are built and then installed every 24 inches along the top plate of the outside walls to complete the roof frame.