- You can learn to build stairs for a mobile home or trailer in few steps.
- Take measurements for the stairs: First, measure the height of the stairs; you will want to keep them a couple of inches below the door opening: this measurement will be the total rise.

Measure the riser height: First, write down the total rise; then convert the total rise to inches. Divide the total rise by 7 (7 is used because this is the recommended height in inches of all stair risers). Take this number and divide it into the total rise. Take the numbers to the right of the decimal and convert these to inches by dividing them by 16. (You use 16ths because that is how many fractions of an inch there are on a tape measure.)

- Lay out and cut the stair stringers: The stringer will be either 2×10 or 2×12 pieces of lumber.
- Place on the stringer and trace out each step, sliding the framing square to the right so that the tread measurement lines up with the last riser line.
- Measure the riser height: First, write down the total rise; then convert the total rise to inches.

Example of how to get unit rise: 4’6″ total rise 4′ multiplied by 12″=48″+6″=54″ total rise in inches 54″ divided by 7″=7.714″ So there will be 7 total risers for the stairs 54″ divided by 7=7.714; Convert .714 to inches .714 multiplied by 16=11.424 or 11/16 of an inch. According to these measurements, the unit rise will be 7-11/16 inches and the stair set will contain seven steps.

Measure the tread width: Convert the total run to inches by multiplying the feet by 12 and then add any leftover inches. Divide this number by 6. Minus 1 from the total number of steps needed for the stairs; you must do this because the concrete slab is counted as a tread. Convert the decimals into inches, and then multiply the three numbers to the right of the decimal by 16.

- Measure the tread width: Convert the total run to inches by multiplying the feet by 12 and then add any leftover inches.

Example to get tread width: 5’3″ total run 5′ multiplied by 12″=60″+3″=63″ total run in inches 63″ divided 6=10.5 .5 multiplied by 16=8 or 8/16 or 1/2 inch. Tread width will be 10 1/2 inches

The tread is 10 1/2 inches and the riser is 7-11/16 inches. According to the measurements, there are seven steps and six treads.

Lay out and cut the stair stringers: The stringer will be either 2×10 or 2×12 pieces of lumber. The stairs will need only two stringers, but you can build with more if you prefer. Take the framing square and tighten the square gauges on the outer edge at the unit riser height and tread width. The tread will be on the tongue of the framing square and the tread will be on the blade of the framing square. (The tongue is the shorter end of the framing square while the blade is the longer end.) Place on the stringer and trace out each step, sliding the framing square to the right so that the tread measurement lines up with the last riser line. (Your last tread mark will be part of the landing.) Reverse the framing square and mark the bottom of the first step. Move the square to the top end of the stringer. Align the tongue with the last riser line and mark the top cut. Cut the stringers, stopping the saw at the end of each line and using a cut out saw to finish the cut. Cut out a notch at the bottom of the stringers to accommodate the bottom plate that you will attach to the concrete slab in step five.

- Lay out and cut the stair stringers: The stringer will be either 2×10 or 2×12 pieces of lumber.
- Place on the stringer and trace out each step, sliding the framing square to the right so that the tread measurement lines up with the last riser line.
- Construct the stairs: Fasten a bottom plate, usually a 2×4, to the concrete slab using a powder actuated nail gun or self tapping concrete screws. This plate will be located where the bottom face of the stairs will be located. There are several ways to attach the stringers to the house; you can nail directly into the joist of the house, nail a ledger plate to the joist to set the stringers on, or use brackets to hold the stringers to attach to the house. Cut the treads out of lumber best suited for outdoor environments. Use split treads, two treads per step, to allow water to drain. Glue with wood glue and screw in place.