How to Add Storage Under Stairs: Framing, Access, and Safety

The wedge of dead space under a staircase is one of the most underused spots in a house. With careful measuring, a code-aware access opening, and the right hardware, it can become drawers, shelves, or a small closet. This guide covers measuring the space, the code rules, framing the access, and building storage that stays safe.

Start by measuring what you actually have

Under-stair space runs from nearly full ceiling height at the high end to almost nothing at the low end. Map the wedge first: tape a line along the floor, then measure the clear height to the underside of the stair at 12-inch intervals, starting at the tall end.

Mark where the clear height drops below a useful threshold. Standing access needs 60 to 72 inches. Shelving or drawers can work with 24 to 36 inches, but anything below about 18 inches is unusable and best closed off behind trim.

Also measure the run length and the stair width, usually 36 inches or more, and sketch a side-view diagram with the heights marked. That sketch drives every later decision.

If you are planning storage before the stair is built, model the rise, run, and headroom first so you know exactly how big the wedge will be. Run the numbers for your own layout at https://stairscalculator.net/calculators/stair-calculator before committing to a design.

Know what is inside the wall before you cut

The wall under a staircase is rarely an empty partition: builders run plumbing, wiring, HVAC ducts, and cable through that cavity. Cutting blind can turn a storage project into an emergency repair.

Open a 4-inch-square inspection hole near the tall end and look inside with a flashlight. If you find a plumbing stack, a duct trunk, or bundled wiring, route your plan around them: moving services is rarely worth it for a storage closet.

Also check whether the wall is load-bearing. The stud wall under a stair is often non-structural, but some layouts use it to help support the floor above. Look for doubled top plates, tight stud spacing, or a wall continuing into the foundation below. If anything suggests the wall carries load, have a structural engineer or experienced framer confirm before removing a single stud.

Code rules you cannot ignore

IRC R311.7.2 requires a minimum of 80 inches of headroom measured vertically from the sloped nosing line of the treads. Your storage build cannot eat into that clearance: keep every shelf, drawer front, and door swing out of the stairway itself.

The enclosed-space rule matters most here. IRC R302.7 says enclosed usable space under stairs must be protected on the enclosed side with 1/2-inch gypsum board. If you close off the wedge, the walls and the underside of the stair facing that space need half-inch drywall, not bare studs or plywood, since the cavity can act like a chimney in a fire.

Never cut or notch the stair stringers. A typical stringer needs at least 3-1/2 inches of uncut material at its narrowest point, the throat, to carry its design load. Frame your storage around the stringers, not through them.

Finally, do not block anything the stair provides for safety. If the stair is part of a required egress path, keep it clear. Do not store gasoline, paint thinner, or other flammables in the new cavity, and keep a working smoke alarm within earshot.

Pick the right storage design for your wedge

Pull-out drawers fit the low-to-mid section best: deep drawers on full-extension slides turn dead space into usable volume you can reach without crawling. The tallest drawers go at the high end, stepping down as the wedge narrows.

A hinged-door closet works at the tall end, where 60 inches or more of clear height allows a 24 to 30-inch door with adjustable shelving behind it. Keep the opening modest, since wider spans need heavier headers.

Fixed open shelving suits the mid zone for items you grab often, since there is no door to open in a tight hallway. Save projects needing new electrical or ventilation for a second phase.

Framing the access opening

Mark the rough opening on the drywall, typically 2 to 3 inches wider than your finished door or drawer bank, and cut the drywall back to the nearest studs on each side.

For openings up to 30 inches in a non-load-bearing partition, a doubled 2x4 flat header is usually enough, supported by jack studs on the sole plate with king studs running full height alongside. This keeps the wall stable and gives the door or drawer face solid mounting.

Cut the existing studs only inside the marked opening, and add cripple studs above the header to tie into the top plate. Keep every new stud at least 1-1/2 inches clear of the stair stringers. When the framing is plumb and square, cover the enclosed side with 1/2-inch gypsum board per R302.7, tape the seams, and the cavity is ready.

The same header and doubled-framing principles are covered in the stair opening framing guide at https://stairscalculator.net/blog/how-to-frame-stair-opening, which walks through sizing framing members in detail.

Building pull-out drawers and shelves that last

Build drawer boxes from 3/4-inch plywood with screwed and glued joints, each drawer shallower toward the low end. Use full-extension slides rated at least 100 pounds per pair, mounted to solid blocking, not drywall. A loaded drawer bank can carry 60 to 80 pounds, and cheap slides will sag within a year.

For fixed shelves, screw 1x2 cleats to the studs on both sides, level across, and drop 3/4-inch plywood shelves onto them. Keep spans under 30 inches so loaded shelves do not bow; adjustable shelf standards are worth the small extra cost, since stored items change.

Line the cavity before installing anything: primer and paint on the drywall plus a simple plywood floor keeps dust down. Caulk the gaps where the new framing meets the stringers so drafts do not migrate into the stair cavity.

Safety, lighting, and finishing touches

A dark, unventilated box under the stairs invites moisture. A 1-inch gap under the door or a small louvered vent keeps air moving and prevents the musty smell of sealed under-stair closets. In a basement or near plumbing, check the cavity seasonally for dampness.

A battery-powered motion-sensor LED strip is the simplest lighting option and avoids new wiring. If you hardwire a light, put the switch outside the closet and keep the fixture clear of stored items.

Finish the exterior to match the room: paint the door or drawer fronts the same color as the trim, add baseboard across the bottom, and caulk the seams.

Since you will already have access to the underside of the treads, it is a good time to silence creaks too. The guide on fixing squeaky stairs at https://stairscalculator.net/blog/how-to-fix-squeaky-stairs pairs well with this build.

Frequently Asked Questions

Can I remove the wall under my stairs to open up the space?

If the wall is non-load-bearing and carries no plumbing, electrical, or ductwork, it can usually be opened up. If it supports the floor above or hides services, you will need an engineer and possibly a reroute plan. Inspect the cavity first.

How much headroom do I need for an under-stair closet?

IRC R311.7.2 requires 80 inches of headroom on the stair walking surface, and that rule is not negotiable. For the closet interior, plan for at least 60 to 72 inches of clear standing height, otherwise drawers or shelves are a better fit.

Do I need a permit to add storage under stairs?

Simple shelving inside an existing finished wall usually does not need one. Cutting studs, adding electrical, or creating a new enclosed room often does. A quick call to the local building department before you start is the safest move.

Can I cut into the stair stringers to gain more storage depth?

No. Stringers are structural, and cutting or notching them reduces the throat depth that carries the stair load, typically 3-1/2 inches minimum at the narrowest point. Build your storage around the stringers instead.

What is the fire protection rule for enclosed space under stairs?

IRC R302.7 requires enclosed usable space under stairs to be protected on the enclosed side with 1/2-inch gypsum board. Cover the walls and the underside of the stair facing the storage cavity, tape the seams, and keep flammable liquids out of the space.

Will under-stair drawers hold heavy items?

Yes, if you build for it. Use 3/4-inch plywood boxes with glued and screwed joints and full-extension slides rated at least 100 pounds per pair, mounted to solid blocking. Light-duty slides on drywall-mounted rails will sag and fail.

Closing

Under-stair storage rewards the homeowner who measures twice and respects the structure. Map the wedge, check what is inside the wall, honor the headroom and fire-protection rules, and build to furniture standards. The result is space you use every day, carved out of square footage you already own.