Floor Joist And Girder

True floor joist span calculations can only be made by a structural engineer or contractor.

Floor joist and girder.

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. For a joist in the field between. Layered framing allows the integration of mechanical systems. Normal spacing is 16 inches on center from center to center though some floors may have joists on 12 inch or 24 inch centers.

Typically used in non residential construction steel joists and joist girders provide an economical system for supporting floors and roofs. 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. Floor joists spaced on regular intervals span the areas between supports such as walls foundations girders and beams. The use of a system of steel joists and steel deck is a solution of choice resulting in significant savings.

For a rim joist at the edge of a floor position the joist near the outer ends of the girders. All vulcraft joists and joist girders are designed and manufactured in accordance to the exacting specifications of the steel joist institute. Wet rot on floor joists girders. Also called soft rot this fungus is known to break wet wood down into cellulose which will significantly weaken and decompose the material when choosing between replacing and reinforcing joists that have been damaged look carefully at the color of the wood.

Place a joist flat atop the girders and perpendicular to the girders. Joists are custom made structural steel components used to support the floors or roof of a building. 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. When replacing rotted floor joists it s important to be sure the girder and sill are still intact.

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. The relationship between joist beam and girder can be either flush or layered framing.