Things You'll Need
Handrails are an important safety feature of any staircase to prevent dangerous slips and falls. When installing a new railing, home owners are often perplexed as to how to determine the proper length. This confusion is because stair handrails typically mount at an angle. However, though the angle plays a minor role in measuring, the process of determining the length of the stair rail is much less complex than it may seem at first.
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Walk to the bottom stair of the staircase and place the end of a tape measure directly on top of the stair tread against the wall. Measure up to the desired distance where you want to hang the railing. Typically the handrail is between 25 and 36 inches above the stair treads.
Draw a small pencil mark on the wall. Move the tape measure aside and place a carpenter's level on the tread vertically. Align it with the pencil mark until the air bubble on the level centers. Erase the mark and reposition it as needed so that it is level.
Walk to the topmost stair tread and perform the exact same procedure at that location. Make sure to maintain the same height used for the first mark.
Hold the end of a chalk line at the bottom mark on the wall and ask another person to stretch the other end up to the top mark on the stairs. Snap the chalk line against the wall to designate the location of the handrail.
Set the chalk line aside and stretch a tape measure from one end of the chalk line to the other. The measurement is the total length of stair railing that you need for the project.