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 Is the mattress protector a full encasement? Can I use a boxspring on top of the high rise platform foundation? How do I choose the correct loft for my pillow? Will the mattress protector reduce the breathability of the mattress?