Framing Methods Structural Components

Balloon Framing

*Balloon framing or Eastern framing the exterior studs run from the top of the foundation to the top of the highest level. Benefits of this type of construction is that wood tends to shrink more in width than in length Because the wall members are continuous from foundation to roof, fewer horizontal members are used, resulting in less shrinkage. The flaw with this type of framing is the danger of fire. A fire starting in the lower level could quickly race through the cavities formed in the wall or floor systems.

Balloon Framing

Floor framing at the mid-level is supported by a ledger set into the studs. *The most common type of wood that is used for framing is Douglas fir.

Platform Framing

Platform or Western Platform framing is the most common framing system now in use. *Platform framing gets its name from the platform created by each floor as the building is being framed. The framing crew is able to use the floor as a platform to assemble the walls for that level.

Floor Joist *The most common spacing of floor joist is 16” O.C. They can be placed at 12” and 24” O.C. depending upon the load.

AFT Systems Advanced Framing Techniques

AFT systems eliminate nonstructural wood from the building shell and replace it with insulation. Reducing the amount of wood in the structure increases the energy efficiency. AFT usually include 24” stud spacing, insulated corners, insulation in exterior walls behind partition intersections, and insulation headers. Many municipalities limit AFT systems to one level construction For multilevel residence, AFT can be used on the upper level, and the stud spacing on the 1st level is altered to 16” O.C.

SIP System Structural Insulated Panels

SIP System is rigid foam insulation laminated between 2 layers of structural board. SIPs have been used for decades in the construction of refrigerated buildings, where thermal efficiency is important. Because the panels do not contain studs, the SIPs do not create a thermal bridge from the exterior face to the interior face. SIPs offer increased construction savings by combining framing, sheathing, and insulation procedures into one step during construction.

EPS System Expanded Polystyrene Foam

Expanded Polystyrene Foam is used as the insulation material used with the SIP system. EPS retains its shape throughout the life of the structure to offer uniform resistance to air infiltration and increased R values over a similar-sized wood wall with batt insulation.

OSB System Oriented Strand Board

Oriented Strand Board (OSB) is the outer shell of the SIP wall and roof exterior sheathing.

Post-and-Beam Framing

Post-and-beam or timber framing construction places framing members at greater distances apart than platform methods. *The sub-flooring and roofing over the beams are commonly 2x6, 2x8, or 1 1/8 tongue-and-groove (T&G) plywood. Many contractors use the post-and-beam system for supporting the lower floor (when no basements is required) and then use conventional framing methods for the walls and upper levels.

Concrete Masonry Units (CMUs)

Concrete Masonry Units (CMUs) are durable, economical building material that provides excellent structural and insulation values. CMUs can be waterproofed with cement based paints and used as the exterior finish, or they can be covered with stucco. Waterproof wood furring strips are normally attached to the interior side of the block to support sheet rock.

Masonry Veneer

A common method of using brick and stone in residential construction is as a veneer, a nonstructural covering material. Care must be taken to protect the wood frame from moisture. Typically brick is installed over a 1” airspace and a 15# layer of felt applied to the framing. The veneer is attached to the framing with 26-gage metal ties at 24” O.C.

Brick Patterns

The position in which a brick is placed alters the name of the unit.

Wythe

Vertical section of wall that is one brick thick.

Bond

The connecting of 2 wythe to form stability within the wall.

Fire Cut

If a masonry wall is to be used to support a floor, a space one wythe wide will be left to support the joist. Joists are usually required to be strapped to the wall so that the wall and floor will move together under lateral stress. The end of the joist must be cut on an angle, called a fire cut. If the floor joist is damaged by fire, the fire cut will allow the floor joist to fall out of the the wall, without destroying the wall.

Mudsill

*The mudsill or sill plate is the wooden member which rests on the masonry foundation and provides a base for all framing above It is attached to the foundation wall with an anchor bolt and is either redwood or pressure treated to prevent moisture damage.

Floor Joists

Floor joists are the structural members used to support the sub-floor, or rough floor.

Cantilever or Overhang

If floor joists extend past their supports they form an extension called a cantilever or overhang.

Rim Joist

The joist that extends around the entire perimeter of a conventional floor joist system and to which the joists are end nailed is called the rim joist.

Bearing wall and non-bearing walls

A bearing wall supports not only itself but also the weight of the roof or other floors constructed above it. Generally a minimum of two top plates are required on bearing walls. Non-bearing walls are sometimes called partitions. A non-bearing wall serves no structural purpose. It is a partition used to divide rooms and could be removed without causing damage to the building. In post-and-beam construction, any exterior walls placed between posts are non-bearing walls.

Stud

The stud is the vertical framing member used to transfer loads from the top of the walls to the floor. Studs are normally placed 16” O.C. (On Center)

Racking

Racking in a stud wall can be caused by wind or seismic loads.

Plywood or OSB

Plywood or OSB used to resist racking is called a shear panel.

*The size of plywood sheets are typically 4'x8'.

Diagonal or Let-in Bracing

An alternative to plywood for shear panels is to use let-in braces. When studs are notched, and a 1x4 is laid flat in the notch at a 45 degree angle to the studs, it is called diagonal or let-in bracing.

Header

*A structural member placed over a door or window opening to support the weight above is called a header.

Trimmer

Trimmer extend from under the header to the sole plate and are used to support the header.

King Stud

A king stud is placed beside the trimmer and extends from the sill to the top plate.

Cripple or Jack Stud

*A cripple or jack stud is placed under the sub-sill.

Double Top Plate

*A top plate is the horizontal member between the roof and where the studs finish.

Facia

The trim board that hides the truss or rafter tails from sight and provides a mounting surface for the gutter is called the facia. It is typically 2 inches wider than the rafter or truss tails.

Overhang

The overhang is the horizontal measurement between the exterior face of the wall and the end of the rafter tail or the outer surface of the facia.

Vertical Rise/Horizontal Run

*Roof slope is the ratio between the vertical rise and the horizontal run.

Securing the Roof

The two names given to the units used to attach a truss to a top plate to help secure the roof during strong wind conditions are: 1) Truss Clip 2) Hurricane Tie.

Ceiling Joist

Ceiling joists are usually positioned across the width of the house and in the same direction as the rafters. The upper corner of the ceiling joist often interferes with the roof slope. To prevent this interference, the corner is usually cut to match the slope.

Reading the Ceiling Span Data Chart

The first column is the spacing of the ceiling joist. The spans are 12” O.C., 16” O.C., 19.2” O.C., and 24” O.C. The second column is the type and grade of lumber that would be used. For our area Douglas Fir would be the type of lumber used. The other four columns are the size of ceiling joist to be used. These sizes are 2x4, 2x6, 2x8, and 2x10. Once you determine the span, the material to be used, and what size of joist then you will look down the column to see what the maximum length the joist be. What would be the maximum length ceiling joist you could use with a 16” O.C, Douglas Fir #2, Dead Load = 10, 2x6 ceiling joist?