Bed foundations are often referred to as box springs, but the two mattress bases or supports differ significantly, and the right one can be key to the comfort and longevity of your mattress. Use a few basics, including mattress type, frame style, aesthetics and even safety to determine if your mattress needs a supportive base, and, if so, what type.
Box Spring or Foundation
As the name implies, a box spring typically is designed with springs that flex or give. A spring mattress usually comes with or requires a box spring, which provides flexible support to maximize longevity and comfort. A memory foam mattress, on the other hand, is designed to shape or conform to your body, and therefore requires a hard, flat surface, such as a durable, non-spring foundation or a particular bed frame.
Speaking of Bed Frames
Although your mattress type determines whether you need a box spring or foundation, your bed's frame determines whether you need a mattress base at all. For example, metal bed frames are made for mattress sets -- a mattress and box spring or mattress and foundation. A platform bed, however, is designed for a mattress only.
Why Box Spring Size Matters
For obvious reasons, your box spring's surface dimensions must match the mattress's, but its depth can be important too. If you have an overly thick pillowtop mattress and metal bed frame, for example, a low-profile box spring provides support, while limiting overall height. A too high -- or too low -- bed can cause access issues, depending on the user's height, age and physical restrictions.
Perfect Pairing or Hazardous Duo
Mattresses typically have box springs or foundation "mates," but you can replace just one or the other if you aren't concerned about mismatched patterns or an off-color look. If you only want a new mattress, check that the old box spring doesn't appear cracked or swayed -- a droopy, worn box spring results in a sagging mattress or creaking bed. Also, make sure the piece you plan to keep meets recent standards for flammability -- an old bed made from substandard materials can be a fire hazard.
In certain cases, a mattress manufacturer only honors the warranty if you use the particular box spring or foundation designed for the mattress. Check your warranty for details.