Residential Wood Frame Construction Explained
Use studs, Headers, and Cripples to Build Load and Non-Load Bearing Walls
© 2008 by Kelly R. Smith; all rights reserved; content may not be copied, rewritten, or republished without authors written permission.
Residential wood frame construction; photo © KSmith Media, LLC
This article was updated on 08/04/20.
This article explains wall layout and wood framing. Learn how to use top plates, bottom plates, studs, headers, and cripples to build load and non-load bearing walls.
Since the early 1920s, almost all homes have been built using wood frame construction. The reasons for this are both economic and structural. Wood studs, typically 2 X 4 pine boards, are inexpensive and strong.
The hubbub at a home construction site may be confusing to the innocent bystander but understanding wood frame construction is actually very simple. Most framing carpenters use circular saws at the work site.
Balloon Frame Construction Versus Platform Frame Construction
Houses with more than two stories have two choices of wood frame construction methods. The terms are self explanatory. With balloon frame construction, the studs making up the exterior walls are one piece and go from the ground to the ceiling level of the top floor. Beginning in the mid 1930s, balloon framing began to fall out of favor.
Platform frame construction, on the other hand, treats each story as its own modular unit. The first floor is built and the ceiling joints are set and then the second floor is built on top.
In the old days, plywood was nailed to the top of the first floors ceiling joists; this is the second floors subfloor. But after a couple of years, the floor would start squeaking because the nails were working loose. So today, the plywood is glued and screwed.
In either case, the framing is built on a foundation, either a concrete slab or a subfloor.
Platform frame construction is simply easier to build and the need for extra long studs evaporates. This keeps building costs down in an industry where every penny counts.
Load Bearing Walls Versus Non-Load Bearing Walls
These are two types of interior wall framing. Again, the terms are self explanatory. As a general rule, load bearing walls run perpendicular to the roof trusses (rafters) or ceiling joists. They bear the weight of the roof and structure above them.
Non-load bearing walls (interior partitions) are any walls that are not engineered to perform any weight bearing function.
When any home remodeling or repair is being planned, careful consideration should be given to load bearing walls. Any moving or removing of load bearing walls must be done in such a way that the homes structural integrity is not compromised.
The Anatomy of an Interior Wall
Understanding the anatomy of an interior frame wall isnt difficult; think of it as the homes skeleton. Interior wood stud walls can be built in any direction but are usually built at right angles to each other.
Interior walls (and exterior walls for that matter) have three basic components: the top plate (doubled), the bottom plate, and the studs that connect them. The spacing between the studs depends on the local building codes.
The most common spacing is 16 or 24 on center. This makes drywall hanging easy and minimizes the amount of drywall finishing. Once again, pennies count in this game.
Spanning Wall Breaks with Window and Door Headers
There are three places where wall studs are discontinuous. In the case of windows, the top and bottom plates are still there but with doorways and case openings the bottom plate is missing. So, how can the wall retain its strength, especially if the wall framing is load bearing? Enter the header.
The window or door header spans the distance between the existing studs and the area between the header and the top plate is filled with short studs, called cripples.
The same 16 or 24 spacing is maintained. Headers are nailed between the studs long side vertical and short side horizontal. This takes advantage of the strength of the grain in the lumber. The header consists of two boards back to back. For a short span 2 X 4s are used but longer spans demand 2 X 6s.
Thats residential wood frame construction in a nutshell. Once exterior sheathing and interior drywall are installed, the homes strength increases exponentially.