Storage space is always precious, especially if you have children's toys and games to keep organised. Use the space under a staircase to keep everyday clutter out of the way, to build a wine rack or to create storage for winter clothes. You'll need a floor under your stairway, a good idea of where the load-bearing walls and suds are located--and a plan.
Decide which direction to use for access. Locate load-bearing walls and studs. You can open the area under a staircase from the side to build shelves or drawers for a storage area that is handy for everyday use, or enter the area under a stairway from the rear to create a closet-like space.
A side-access storage area is handy in a basement or on main floors. Remove the wall, taking care to avoid studs. If you have to remove framing studs, be sure to add a reinforcing stud on either side of the opening as well as a header (one or two-by-four across the top of the new studs) to frame out your openings for shelves or drawers. Frame in supports for drawers or shelves using these frames, matching framing along the back wall of the staircase and supports between the two.
A stairway closet, with entrance from the rear, provides storage for tools and supplies in the basement. Mount supports for shelves on stringers and lay shelves in on top. Install peg board along the sides to hang tools and to hold supports for deeper shelves. A door at the back of the staircase can keep little folks out.
Build sliding drawers, shelves or pivot bins for your under-stair storage, depending on how your storage will be used. Many home improvement stores sell various types of storage for closets that can be used for this purpose. You could even put in a clothes rack to hang off season sportswear and outerwear.
Unless you plan on open shelves, you'll want to consider some cabinetry on the front of your storage space. A bin or drawer front is fine, but if you're installing storage shelves, you might want some doors to cover them up. You can build these yourself, find stock-sized doors at home centres or shop garage sales for old cabinet doors. Dress up plain fronts or finish edges with trim, found at any home centre or hardware store. Finish your storage area with paint or paper or varnish.
Most modern staircases are built with a centre stringer (the upright piece that the stair treads sit on) as well as side stringers. These stringers can be used to anchor the framing for shelves and drawer supports. Keep in mind that you should have a plan, work from the back wall to the front wall, and provide support for any drawers or shelves--they will be carrying considerably more than their own weight. If you're building storage for the kids, consider painting each child's bin or shelf a different colour and letting each paint her own space. A reciprocating saw is handy for demolition, and a nail gun helps cut down on time necessary to pound all those nails. Both can be rented by the day or week.
As with any remodelling, check walls for load-bearing elements and electrical lines or plumbing before demolishing. Always wear safety glasses and gloves when demolishing walls. Always wear safety glasses when using tools or in a construction area.