Short answer
The underside of a mattress collects moisture from the sleeper and dust from under the bed, especially on floors, solid platforms, storage beds and after storage or a move. The EPA calls moisture control the key to mold control. Air the bed, keep humidity at 30 to 50 percent, and have the underside cleaned with the top. Underside treatment is +$50–$75 per mattress.
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Regular price $249, Fall 2026 promotion price $199first mattress, any size · Fall 2026 promotion
HEPA vacuuming, enzyme treatment for organic odor, dry vapor steam and UV-C. We recommend cleaning twice a year.
By Matthew Brunken · Updated October 24, 2026 · Last reviewed October 24, 2026 · Sources · Editorial standards
Most mattress cleaning stops at the top. The underside is where moisture from the sleeper settles and where dust from under the bed collects, and it's what changes most when a bed sits on the floor, in a storage unit or in a moving truck.
Related reading: can mattress moisture lead to mildew or mold?, surface moisture vs saturation, should you sanitize a mattress after moving?, can a used mattress be sanitized? and the mattress odor guide.
The first mattress is $199 Fall 2026 special (regularly $249), and underside treatment is +$50–$75. Take the 60-second quiz or schedule your cleaning. We recommend cleaning twice a year.