Do your sheets work on a mattress over 11" thick? April 06, 2022 19:29 Yes, our sheets are designed to fit mattresses with a thickness from 11" to 14". Related articles How long can my mattress stay in the box before I open it? Is the mattress protector a full encasement? Will your mattresses develop body impressions? Will the mattress protector reduce the breathability of the mattress? Are your pillows washable?