Just because you ‘can’ do something does not mean you should according to Garage Flooring LLC’s Justin Krauss. Many customers call, or worse yet, order garage floor mats and tiles with the intention of putting them over carpet. This can be a major issue and will not fall under the manufacturers warranty.
First and foremost our products are designed to go over concrete and in some cases a wood substrate. Carpet is not rigid. When the carpet flexes the tiles will flex and so will the rolls.
Tiles can separate and be very unstable. The mats can lift and even cause a trip hazard. In most cases its just a bad idea. There are some cases where it does work OK. Large rolls being placed over commercial glue down carpet often work. The important thing to remember is it is your call. We cannot tell you that it will or won’t work — only that in general its a bad idea.
We also wanted to point out that interlocking tiles give little if any protection to the carpet against stains from fluids. Water, gas, oil etc can easily seep through the seams.