Framing

Framing lumber dimensions

The actual size of a 2”x4” piece of lumber is 1 ½”x3 ½”. 2”x6” -- 1 ½”x5 ½” 2”x8” -- 1 ½”x7 ¼” 2”x10” -- 1 ½”x9 ¼” 2”x12” -- 1 ½”x11

¼”

Nail Sizes

Termite Shields

Metal termite shields are required in many parts of the United States.

Termite Map

Balloon Framing

In balloon framing, now seldom used, the studs are continuous from the sill to the rafter plate. Ends of the second floor joists are supported on a ribbon. They are spiked to the stud as well.

Platform Framing

Most modern residential and light construction uses platform framing. The first floor is built on top of the foundation wall as though it was a platform. It provides a work area for assembling and raising wall sections safely and accurately. Wall sections are one story high. Outside walls and interior partitions support platforms for upper stories. 

Engineered Lumber

Girders and Beams

Girders, also called beams, resting on the foundation walls and on posts or columns, provide the needed support for the floor joists.

Steel Beams

In many localities, steel beams are used instead of wood girders.Sizes depend on the load.The load is calculated in the same way as for wood girders.

Joists

Floor joints are framing members that carry the weight of the floor between the sills and girders.The most common spacing of wooden joists is 16” O.C. (on center).

Double Floor Joists

Joists must be doubled around openings in the floor frame for stairways, chimneys, and fireplaces.

The two joists running parallel with the regular joists are called double trimmers.

The two joists running perpendicular to the regular joists are called double headers.

Floor Joist SystemFloor joists must also be doubled when supporting an interior wall running parallel to the joists. Two methods are shown below.

Joist Hangers

Metal joist hangers are used for support when joists are not supported by a wall or beam below.

Laying out Floor Joists

Floor joists are placed 16” on center.

Floor Joist Layout

Floor Joist Layout

Floor Joist Layout

Butting Floor Joist

When butting floor joists over the beam, 2” lumber of the same width and at least 24” long must be nailed to the joists.

Bridging

Bridging is composed of pieces of lumber set diagonally between the joists to form an “X”.Solid bridging is also called blocking.

Bridging

Place the bridging at the halfway point of the joist span.Use a chalk line for even placement.

Solid-web Floor Trusses

A manufactured type of solid-web floor trusses generally called wood I-beams and are used in place of traditional framing lumber. The main advantage of using floor trusses is greater span distance and they also are more stable which reduces squeaky floors.

Subfloors

The laying of the subfloor is the final step in completing the floor frame.

Sub floor In most modern construction, ¾” tongue and groove plywood or oriented strand board is used for subflooring.Other sheet materials such as composite board, waferboard (also called waferwood), oriented strand board, and structural particleboard are also approved for use as subflooring.

Subfloor

In a glued floor system, the subfloor panels are glued and nailed to the joists.

Studs

Most common spacing for studs is 16”.Trimmer studs are shortened studs that stiffen sides of rough openings that bear the direct weight of the headerCripple studs are shortened studs placed below the rough sill or above a header.Pre-cut (regular) studs on an 8’ tall wall are 92 5/8” long.

Headers

Headers carry the weight of the building across door and window openings.Header length is equal to the rough opening plus the width of two trimmers.

Two Ways to Build Headers

Partition Wall Headers

Smaller 2”x4” headers are used with short cripple studs placed above on non-load bearing partition walls.

Framing Height of Window

The rough opening height is measured from the bottom of the header to the top of the rough sill.

Rough Window Sill

The rough window sill is nailed to the trimmer studs of the window assembly with short cripple studs as support. The internal cripple studs are nailed in place on the 16” center marks of the wall section.

L-corner Framing Method

One method of framing a corner is to build an L channel on the wall that goes all the way to the outside of the floor.This method makes wiring and insulation easier to install.

Partition Supports

Double Top Plates

Plywood Corner Bracing

The most widely used method of bracing the outside walls is to use 4’x8’ sheets of plywood or OSB.

Metal-Strip Bracing

Another method of bracing exterior walls to resist lateral (sideway) loads is metal-strip bracing.

Wall Sheathing

Wall sections should be covered with sheathing before roof framing is started.Sheathing adds rigidity, strength, and some insulating qualities to the wall

House Wrap

House wrap comes in 9’ wide rolls and is designed to cover cracks at wall joints where air might enter or leave a building.

Framing with Steel

Steel-framed residential construction is increasing in popularity. Metal studs can be used with either metal plates or wood plates.