A set of wood steps is needed to get into and out of a mobile home. The stairs are built using pressure-treated lumber that will resist deterioration due to moisture or insects. You can buy the materials needed for the stairs at your local lumber yard. Check with your local permit department to see if there are any restrictions that must be followed, and if you have to obtain a permit before you start the construction of the steps.
Call the permit department in your area to check on any restrictions or permits needed to build the stairs for the mobile home. It is for your protection to ensure that the requirements are followed in order to create a set of stairs that are structurally sturdy.
Place stair hangers on the rim joist of the deck or landing. Set these so that the stair stringers rest against the rim joist. Code for most areas of the country states that the landing must be the same size or larger than the width of the steps. Use galvanised joist nails to attach the hangers to the deck or landing. Use the same nails to fasten the stair stringers to the stair hangers. The standard width for stairs is 36 inches wide. Place the hangers 2 feet and 9 inches apart. Place a third hanger in the middle. This will make a 36-inch set of stairs when you overhang the stringer by 1 1/2 inches.
Place the stair stringers into position. The pre-cut stringers from most lumber yards are designed for use in mobile homes. Normally, you do not have to cut these to length. If you have to cut these down, use a circular saw and a straight edge for this task. Nail through the stair hangers into the stair stringers to anchor them in place.
Cut the 2-by-12-inch pressure-treated boards to 36 inches in width. This will leave a 1 1/2-inch overhang for the tread. You can also add a piece of 2-by-12 material for the vertical riser of the stairs. This is not usually required by code for exterior stairs, but adds a finishing touch that many people prefer.
Screw down the treads to the flat portion of the riser with 3-inch exterior deck screws. Use (three) at each stringer location. A power screwdriver works best for this application.
Stain the stairs with a good exterior deck stain after the stairs have weathered for 30 days. The chemicals used in pressure-treated wood will resist the stain until it has had a chance to air dry for 30 days. Use a quality 3-inch paint brush or thick nap roller for this step. Apply stain every three months until the stairs have a chance to absorb the stain. This will help to protect the stairs from the weather. You should only need to do this a couple of times.
For a set of stairs over 30 inches wide, add a centre stair stringer. This is to keep the stairs from bowing in the centre. This is for your safety. Reapply a coat of stain or water repellent annually to keep the stairs in good condition.