How to Convert a Metal Staircase to Wood

Preparation

• 1

  Measure the step rise and the step run on the existing metal stairs. Also take note of the total number of steps. If the stairs were built in compliance with local code regulations, you can often simply transfer the measurements to a new, wooden staircase and proceed with marking and cutting the stringers. Other options include using an online stair calculator or manually calculating the stair dimensions.

• 2

  Tear the old staircase out. Unbolt the top of the stairs from the upper floor and the bottom from the floor of the lower level. Disengage any fasteners attaching the stringers or the rails from existing side walls. Depending on the location and methods used, you may have to perform this work differently; however, removing the stairs will be self-explanatory. Just work carefully to avoid damaging walls and floors.

• 3

  Find the total stair rise, which is the distance from the lower level's floor straight up to the finished floor surface on the upper level. Divide the total rise, in inches, by 7 to determine the number of steps your stairs require. An 86-inch total rise, for example, divided by 7 yields 12.28 steps. Round off to the nearest full step -- 12 in this case.

• 4

  Divide the total rise by the number of steps obtained to calculate the step rise for each step on the stairs. Using the previous example, 86 inches divided by 12 results in a step rise of 7.16. Building code defines the ideal rise as 7 inches; thus, this step rise is adequate. If the rise varies much -- yielding 8 inches for example -- recalculate to identify errors. In addition, adding a step lowers the step rise and taking a step away increases it.

• 5

  Multiply the number of steps by 11 inches -- the step depth, called the run -- to calculate the total stair run or the length the stairs travel horizontally. Building code and research indicates that 11 inches is the ideal step depth. Like the step rise, it can be lengthened or shortened to create a steeper or gentler slope. Determine your local code requirements before greatly varying from the ideal.

• 6

  Square the total stair rise and the total stair run. Add the results together. Find the square root of this sum to determine the stringer length, again in inches. Add a couple inches to this figure to allow for error. Cut the stringers to the required length.

Building and Finishing

• 7

  Create a stair jig, which is a template of the steps, by attaching a straightedge to a carpenter's square. Align one end with the step run and the other end with the step rise. Clamp in place to prevent the measurements from shifting.

• 8

  Set the jig on the stringer material, allowing the point to rest on the wood and the straightedge to fit against the stringer edge. Trace around first the rise, closest to the stringer end, then the run. Continue down the length of the stringer, sliding the jig and tracing the step outline.

• 9

  Cut the outlined step pattern from the stringer board. While you may use a circular saw for most of the stringer, when you get close to where the step rise meets the step run -- the innermost portion of each step -- switch to a handsaw. Cutting past the cut marks, into the remainder of the stringer, weakens the stringer.

• 10

  Place the completed stringer on top of another stringer board. Trace around each step run and rise. Cut out the stringer similar to the first. Visually compare the stringers before proceeding.

• 11

  Measure from the bottom step down toward the stringer end, making a mark at the step rise, less 1 inch. Repeat in at least one spot parallel to the first. Connect the marks with a square and draw a line across the board end. Cut the material below the line free. This shortens the stringer to the proper length while allowing for the thickness of the tread material.

• 12

  Flip the stringer over, end for end, and repeat the process at the top of the stringer. Run the tape measure from the rise forming the last step back to the run measurement. Use at least two measurement marks and cut to obtain a precisely fit stringer.

• 13

  Attach each stair stringer in place of the old metal ones. Secure to the top floor with joist hangers or as previously attached and again to the floor, following the procedure used to hang the old stairs. Finish the stairs with treads, made from 1-inch thick plywood or dimensional lumber and risers if desired. Attach risers -- the vertical board at the back of each step -- before the tread and attach with nails driven into the stringer.