Building under-stair storage: plans, carcasses and custom drawers

The space under a staircase is almost always wasted, when just a few carcasses and doors would turn it into precious storage, whether for shoes, books, toys or household linen. The difficulty comes from the slope of the stairs, which requires precise measurements and particular angles at each level. Here is how to build simple, robust, custom under-stair storage, even without expensive machinery.

The tools and materials

• 18 mm MDF panels or plywood: a robust and economical choice
• Jigsaw, circular saw or panel cutting; square, ruler and tape measure
• 4 x 40 wood screws, wood glue, clamps
• Drawer rails or slides if you choose drawers
• Hidden hinges and handles, or piano hinges for the doors
• Wood filler, paint or varnish for the finishing

18 mm MDF is the simplest choice for a first project: it cuts clean, does not split and paints easily. Poplar or birch plywood, lighter and more moisture-resistant, suits areas near a front door better. For large panels, have the sheets cut in-store: it is free, precise and avoids jigsaw burrs.

Taking the measurements correctly

1. Measure the height, width and depth of the space under the stairs at several points
2. Identify the slope of the stairs by measuring the stringer height every 20 cm
3. Reproduce the slope profile on a cardboard template before cutting
4. Allow 5 mm of play between the carcasses and the walls for expansion
5. Note the position of any cable or pipe routes before fixing
6. Check the levelness of the floor: an uneven floor skews all the measurements

The slope of a staircase is almost never perfectly regular: each step brings its own deviation. That is why the cardboard template is essential: it fits the real profile of the stringer exactly, including its irregularities, where a simple measurement of the theoretical slope would deceive you. Then transfer this template to each side panel, which will serve as a reference for all the other cuts.

Building the carcasses

1. Cut two side panels with the top following the slope measured on the template
2. Cut the shelves and the bottom to the dimensions of the interior width
3. Assemble the bottom and the shelves between the two sides with glue and 4 x 40 screws
4. Check the squareness with a square before the glue sets
5. Let the carcasses dry under clamps for at least 4 hours
6. Reinforce the corners with metal brackets if the carcass is tall

Installing the carcasses and doors

1. Put the carcasses in place in the space and shim them with wooden wedges
2. Fix each carcass to the wall and its neighbors with brackets or screws suited to the support
3. Cut the doors in MDF, following the template of the front face
4. Mount the hinges and handles, then adjust the closing of the doors
5. Paint or varnish the whole once the adjustment is finished

Sloped doors are always harder to adjust than vertical doors: you have to rely on a set of hidden hinges with adjustment screws, which allow correcting the position in all three directions. Mount the hinges on the carcasses before the final installation, then adjust after fixing. A ball or shell handle integrates better than a bar handle under a staircase.

Variant: sliding drawers

Instead of doors, you can install drawers on rails in the tallest and deepest areas. Each drawer follows the slope of the stairs: the front face is cut at an angle while the bottom remains horizontal. Full-extension rails make access to the back easier, and a travel stop prevents the drawer from tipping when loaded. Also think about a push-to-open mechanism without a handle for a sleek look, provided you choose soft-close rails.

The mistakes to avoid

• Cutting the panels before checking the measurements on the cardboard template
• Forgetting the expansion play: the carcasses stick to the walls in summer
• Drilling into the walls without detecting the pipes and cables
• Choosing panels that are too thin: a 12 mm shelf sags under books
• Forgetting the ventilation: a closed carcass against a damp wall molds

Building under-stair storage requires patience for taking measurements, but the construction itself remains simple and within reach of a beginner woodworker. In a few weekends and with a moderate budget, you turn dead space into useful, durable storage perfectly suited to your interior, while adding value to your home.