It’s usually best to put your mattress on a hard floor. However, not just any old hard floor will do. Finished surfaces like treated hardwoods, tiles, polished concrete, and similar flooring are best to put your mattress on because they offer the most support and stability and don’t retain as much moisture as linoleum or unfinished plywood. It’s generally better to avoid putting your mattress directly on a carpeted floor, as carpet can increase the odds of mold growth and musty smells. So if you have carpet, make sure to lay a bunky board, rubber mat, or some other type of barrier between it and your mattress. Also watch out for older hardwood floors, since these might be untreated or at least less-effectively treated. Loose boards can also provide better hiding places for pests.