Marking Out Floor Joists

Joists placed 24 on center are usually adequate.

Marking out floor joists.

To avoid confusion we mark an x on the side of the line to which the joist will be placed. The floor joist spacing is the distance between the centers of any two installed joists. See the image below for an example of joists spaced 16 on center 16 o c. In this application floor joists are placed 16 oc and layout has been started from the right side.

Then a string line can be fixed to the top of these two new joists giving you the level for the joists in between. And mark another joist location 4. Wood joists are structural framing members that are laid upright on edge and nailed equally spaced usually 16 inches on center onto the wall plates. Floor joists should be spaced no more than 16 inches 41 cm apart from center to center to provide adequate stability.

Mark the joist location with a speed square 3. Starting from a nail nailed at the center of one of the two outer joists already in stalled measure along the ledger making a clear mark every 24 or 16. After you have determined their spacing the layout is rather simple. So long as your lines are 16 apart your joists will be 16 o c.

These marks indicate the center of each joist. Joists range in size from 2 x 6 to 2 x 12 based on the distance being spanned. Since the example house we are designing for is 12 feet wide we need to find in the floor joist span table a joist size and centering that can span 12 or wider. Use a tape measure to measure 16 inches 41 cm in from the edge of the rim joist and draw a small notch.

Laying a floor joist in a wood frame house is a simple procedure that can be done in 4 easy steps. The string line would be fixed in position x in the diagram below. Nobody with any sense actually lays out joists by measuring to their center. Mark the position of each floor joist along the sill plate.

Each corresponding measurement should be 3 4 of an inch shy of stud marks. Joists are cut to lay flush with the outer surface of the. The first joist is marked at 15 1 4 to ensure that the 4 or 8 edge of a panel will fall on the center of a joist. Measure between the joist locations along the angle to find the on center joist spacing 5.

The layout for the following joists is then oc. Slide the tape and square along the joist until the tape reads 32 in. To level the entire floor it is best to start with the two end joists.