Floor Joist And Girder

Floor joists or beams provide the below surface support for the wood subfloor of a room.

Floor joist and girder. Place a joist flat atop the girders and perpendicular to the girders. The main difference between girder and joist is that the girder is a main horizontal support of a structure which supports smaller beams often with an i beam cross section composed of two load bearing flanges separated by a stabilizing web but may also have a box shape z shape and other forms and joist is a horizontal structural element transferring load from flooring to beams typically running perpendicular to beams. The relationship between joist beam and girder can be either flush or layered framing. For a joist in the field between.

Flush framing with top of joists beams and girders flush with each other requires less structural depth but may require additional depth for mechanical systems. Layered framing allows the integration of mechanical systems. For a rim joist at the edge of a floor position the joist near the outer ends of the girders. Though joists may be any size that you desire using typical floor joist and beam specifications ensures that you can find hardware to fit the joists and that the floor provides adequate support for furniture and other items in a room.

True floor joist span calculations can only be made by a structural engineer or contractor. Normal spacing is 16 inches on center from center to center though some floors may have joists on 12 inch or 24 inch centers. Joists are custom made structural steel components used to support the floors or roof of a building. When replacing rotted floor joists it s important to be sure the girder and sill are still intact.

Typically used in non residential construction steel joists and joist girders provide an economical system for supporting floors and roofs. All vulcraft joists and joist girders are designed and manufactured in accordance to the exacting specifications of the steel joist institute. The use of a system of steel joists and steel deck is a solution of choice resulting in significant savings. Joists are usually supported by a sill a long horizontal timber that s the lowest part of the framework and rests on the foundation or a girder a large beam that s the main support of the building.

Floor joists spaced on regular intervals span the areas between supports such as walls foundations girders and beams. 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.