10 basement storage ideas for a damp-prone space

Measure the humidity before you buy a single shelf

Mold needs moisture. The EPA says to keep indoor relative humidity below 60 percent, ideally between 30 and 50. Put a digital hygrometer on the wall and watch it for a week in the wettest season. A dehumidifier that drains to a floor drain or sump fixes most basements, but university extension services point out that it only treats the symptom. Check the causes too: clogged gutters, downspouts emptying at the foundation, grading that slopes toward the house. A one-inch rain puts 1,250 gallons on the roof of a 2,000-square-foot house.

Everything off the floor and a hand's width from the walls

Concrete floors and foundation walls are the coldest surfaces in the house. Moisture condenses there first, and floodwater arrives there. Put everything on shelving, pallets or risers a few inches up, and leave a gap behind the shelves for air (State Farm suggests three inches). The bottom shelf is for things that can get wet, like plastic totes of hard goods and metal tools. Cardboard, fabric and electronics never sit on the floor.

Sealed plastic totes, not cardboard boxes

The CDC says mold grows on paper, cardboard, ceiling tiles and wood. Basement cardboard soaks up moisture, goes soft, and attracts mold and silverfish. Use rigid plastic totes with latching or gasketed lids, all one size so they stack. Add a desiccant pack to any tote holding fabric or paper. If you need an original box for a return or a move, put the box inside a tote.

Choose shelving that handles damp, and anchor it

Particleboard swells and sags in a basement. Use steel wire, welded steel or heavy resin shelving rated for the load, with the heaviest totes between knee and shoulder height. Anchor tall units to studs or with masonry anchors (the CPSC's Anchor It campaign covers the straps). Light, bulky things go on top.

Zone around the mechanicals, and keep them clear

The furnace, water heater, electrical panel, sump pump and main shutoffs need to stay reachable. Nothing flammable goes near the furnace or water heater: no paint, solvents, gasoline, aerosols, paper or fabric. Leave a clear path from the stairs to each one. Long-term archives go in the far bays, and household overflow you use often (paper towels, pantry backstock) goes near the stairs.

What not to store in a basement

These don't hold up well down there, even at 50 percent if the number creeps:

• Paper and photos. The Library of Congress lists basements, along with attics, as places to avoid for photographs. Books, documents and artwork belong upstairs.
• Fabric, upholstered furniture, mattresses, rugs. They absorb damp and keep the smell.
• Electronics and instruments. Condensation inside a cold device causes corrosion.
• Firewood. It holds moisture and brings in insects.
• Fuel and flammables near the furnace. Keep gasoline and solvents in the garage or a detached shed, in approved containers.
• Food in cardboard, pet food, birdseed. These draw mice and pantry pests.

If one of these has to stay, seal it in a tote with a desiccant, put it on an upper shelf in the driest corner, and check it each season.

Use the under-stair bay and the joist bays for long, flat things

The space under the stairs fits skis, folding tables, a ladder, or a few shallow shelves. Between the ceiling joists, simple cleats or hooks hold long, light items like trim, curtain rods, fishing rods or a bagged artificial tree, up and away from the damper air near the floor. Leave plumbing shutoffs, junction boxes and the drain cleanout accessible.

Plan for the night the water comes in

Assume it will happen at least once. Keep anything you'd hate to lose on the upper shelves or upstairs, and use the bottom shelf only for things that can take a soaking. Put the chest freezer and other appliances on risers. Test the sump pump every spring and consider a battery backup. A labelled bin of flood supplies (towels, a wet-dry vac, a fan, heavy bags) by the stairs means you aren't hunting for towels in ankle-deep water.

Light the aisles and face every label out

Add a light at the bottom of the stairs and over each storage bay (plug-in LED shop lights are fine). Face labels toward the aisle in letters you can read from six feet. A code on the short side plus a two-word name works better than a contents list that goes out of date. Keep aisles at least two feet wide so you can carry a tote through.

Keep an inventory with photos, and audit it by nose twice a year

A musty smell usually means something porous on the far shelf has started to go. Photograph the inside of every tote before it's shelved and keep the photo with its location. Twice a year, after the spring thaw and before winter, walk the basement with the hygrometer, smell the corners, check the bottom shelf, and pull anything that's gone soft or spotted.