Mattress Ratings >> Innerspring Mattress Ratings
What Is an Innerspring / Coil Mattress?
Innerspring mattresses use wire coils for the main support structure.
On top of this structure is upholstery which is separated from the innerspring system by an insulator, padding and wire or netting layer that keeps the upholstery from sinking into the coils. The upholstery consists of layers which are made of man-made materials, natural fibers and a variety of foams. Every mattress has about 3-8 layers of padding, with each layer being a different material.
Types of Coils
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Open Coil / Bonnell Coil: This hourglass-shaped wire coil is connected to adjacent coils by small wire spirals called helicals. This type of coil usually gives good initial comfort support but may wear faster than more advanced coils.
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Offset Coil: This coil is similar to the open coil but has a squared head, which may let the mattress contour to one's body better. An offset coil is somewhat more cylindrical than an open coil, which may allow it to have somewhat more durability.
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Pocket Coil / Independent Coil: A pocket or independent coil is a cylindrical spring wrapped in its own fabric pocket. It is designed to provide better contouring ability. A mattress using this type of coil provides good motion isolation because each coil works independently. In other words, each pocket coil absorbs the weight placed on it without distributing the load to other coils. The result is that one sleeper will not be disturbed much, if at all, when another person moves on the bed.
- Continuous Coil: Each row of coils is constructed by a single wire attached to the next row by helicals. A continuous coil is often made into a lattice of coils instead of rows, which allows more coils per mattress than other coil types. This design lets each coil deflect weight to a higher number of springs resulting in reduced stress on each coil.
Box Spring / Foundation
A box spring or foundation will often extend the life of the
mattress.
A true box spring features a coil or modular coil spring system
within it. These coils provide shock absorption, so that when
pressure is applied to the top of the mattress, the box spring
gives slightly underneath.
Some mattresses use a foundation, as opposed to a box spring.
Framed in wood or steel, foundations look similar to box springs
but are solid and, consequently, have no give or shock absorbing
abilities. Foundations typically will last longer than box
springs since they have no moving parts to wear out.