When shopping for a mattress for a platform bed, there are a few things consumers should consider. First, the way a mattress feels when you try it in the store is partly due to its matching foundation (box spring) – they are engineered to work in tandem with one another. When you replace the foundation with a platform bed's rigid surface, the feel will be different – generally, firmer and less resilient. You might also want to consult with your salesperson to determine if there are any changes in warranty coverage for a mattress used without its matching foundation.