Floor Joist Are Usually What Size In Residential Construction

When building a house or even a deck it is important to confirm you have the correct joist sizes spans and spacing before you get started.

Floor joist are usually what size in residential construction.

Types of floor joists the three main types of floor joists used in home construction are solid lumber i joists and open web floor trusses. Putting all these factors together gives the minimum size joists needed for various types of wood grades of lumber sizes of boards spacing of joists and the load that will be placed on the floor. Floor joists are typically 2 by 8s 2 by 10s or 2 by 12s. Some newer homes have manufactured i beam shaped joists.

Joists must exhibit the strength to support the anticipated load over a long period of time. Ceiling joists are usually 2 by 6s or sometimes 2 by 4s if it is an older home. This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction. A floor s framework is made up mostly of wooden joists that run parallel to one another at regular intervals.

Considering the cross section of a typical joist the overall depth of the joist is critical in establishing a safe and stable floor or ceiling system. While most residential construction uses 2x8 joists with 16 inch spacing there are many other factors you need to consider when determining the proper joist span length. While joists can be made from many materials those used for residential construction are usually solid or engineered wood.