With wood stairs the first and last tread have to be handled differently than all of the other treads. Once you have the first and last tread of your stairs figured out, all of the other treads easily fall into place. This article will give an overview of how to handle the first and last step so that you have even, secure stairs that last a lifetime.
Step 1- Anchor the Stair Stringer
The first step of building your first stair tread is to make sure that you accurately install the stringers. Stringers are the angled cut boards that help support the entire stair's weight. Much like chocking the wheels of a car so it doesn't move, you need to anchor the stringers so the stairs do not slide where they meet the floor. If you have begun the construction of your stairs, you either cut yourself or purchased pre-cut stringers.
You also have the outline of where your stairs will start along the bottom floor. At that start line you need to anchor a 2x4 called the kickboard to the cement or wood floor, depending on the type of your construction. For the bottom part of your stringers, if they were pre-cut they may already have a notch cut out at the bottom for the kickboard, if not then you need to cut one. If the floor is wood you can screw the kickboard into position. If the floor is concrete it is wise to use lead anchors and lag bolts. Use metal angle brackets or toe nail the stringers to the kickboard.
Step 2- Secure the Stringer to Upper Floor
Now that you have the anchoring taken care of, you need to attach the stringer to the upper level. The stringer can be supported by the upper floor joists, or the floor support wall if there is one. The first option is the use of a 3/4 inch plywood hanger board. The use of a hanger board is the most convenient method of fastening the upper portions of the stairs in locations where there is no support wall behind the staircase.
Do not use any kind of particle board or other processed lumber for this, it will not be able to support the weight of the stairs over time. Attach the hanger board to the stringers, and then the hanger board to the floor joists. An alternate method of attaching the stringer is to use a 2x4 ledger board. The stringers will need to be notched to accommodate the ledger board. The ledger board is first nailed to the stringers and then to the support wall. The 2x4 ledger board works best when there is a support wall behind the staircase. Make sure the support wall is properly attached at the top and bottom and that the studs are in good shape.
Step 3- Install the Risers
Now that you have the stringer securely fastened both above and below, you can start on the risers. The risers are installed first, and are cut somewhere between 7 to 8 inches depending on your stair plan. The risers sit behind the stair tread, so that is why they need to be installed first. The risers can be nailed into the stringers from the front, or if you would prefer not to have marks that have been filled with nail hole putty, you can use glue and nail blocks, or use metal angle brackets attached to the stringer and then screw the risers into place from the backside of the staircase.
Step 4- Install the Treads
Now that they risers are installed you can start securing the treads to the stringers. Use construction adhesive and nails or screws. Wood blocks or metal brackets can be used if you prefer not having any fastener marks visible from the top side. On staircases that have risers, the stair tread should have a nosing that extends 3/4 inch to 1-1/4 inches out, past the face of the stair riser. You will start with placing the tread on the first step and continue up the stairs until you have reached the top landing. Then you are done with all of the treads and risers and all that is left is the railing and balusters.