Installing floating wooden stairs can be an easier job than trying to install traditional wooden stairs. Rather than having to cut and measure stringers, you have one center metal pole that stretches from the lower floor to the upper floor and brackets that hold each wood tread to the pole. It is a simple and attractive design.
Like any stair project, the first step is to measure for your floating wooden stair. You first need to determine your floor to floor measurement. Not floor to ceiling, you need to measure from the top of the finished floor upstairs down to the floor on the bottom. Using this measurement you can order your metal support spine accordingly. While it is possible to build an entire floating stair yourself, the amount of metal that needs to be welded is beyond most-do-it-yourself types.
If you plan on tackling this type of project yourself, it is best to order the floating stairs as a kit that includes the metal center pole, brackets, and wood treads. Since the floor to floor height is the only one you need to do yourself, we will follow the rest of the directions as though you had purchased a kit.
Mount Center Pole
First, insert the base plate and top header plate into the center support tube. Find the exact center of the opening you are using for the stairs. Then measure 9 inches to each side of the center line and draw a plumb line. Measure 1 inch below the finished floor and draw a line.
With help, lift the center support tube up to this line. Then drill seven 32-inch pilot holes and secure with six 5/16x3-inch lag bolts. Align the center support tube and the drill seven 32-inch pilot holes for the base plate and attach with four 5/16 x 1 1/2-inch lag bolts.
Attach Tread Supports and Treads
Now, calculating the riser height using a chart, for example, if your floor to floor height is 8 feet 8 inches high, you will have a riser height (meaning how far apart the stairs are) of 8 inches. Then find the corresponding mark on the center tube and minus 1 inch for the width of the tread. So, you would set the first tread support at 7 inches.
This is also where you set the bottom locking sleeve. You then attach the remaining tread supports from the bottom up following this procedure: Slide the locking sleeve up from the underside of the center support. Then place the steel tread support on top and align the holes.
From below insert four 5/16x5/8 hex head bolts. Place a lock washer and hex nut over the bolt and then finger tighten. Set your exact riser height, and then tighten the top two bolts and then the bottom two bolts. Make sure that it remains level. Then position the wood treads so the bottom back end touches the center support, center the width, and then fasten with 6 3/4-inch pan head screws from below. Repeat this process for all of the remaining treads.