The mattress support layers, also known as its core, includes all the layers below the quilting and comfort layers of a mattress. They are primarily responsible for spinal alignment which as you know is one of the two main functions of every mattress. They do this by controlling how deeply different parts of your body sink down into a mattress while you sleep. In some mattress constructions, particularly those with thinner comfort layers, they have secondary functions of helping the comfort layers to form a pressure relieving cradle and helping to hold up the more recessed parts of your body profile such as the lumbar.
There are five basic types of mattress cores. These are Innerspring, Latex, Polyurethane, Airbeds, and Waterbeds. They may be made up of a single layer of material or several layers made of different materials. It is important not to confuse what is needed for pressure relief with what is needed for spinal alignment as these two functions are interconnected but separate. Pressure relief is connected to the "softness" of the comfort layers and spinal alignment is connected to the "firmness" of the support layers and making one firmer or softer in the hopes of improving the other will rarely be successful.
A brief description of each type of mattress core or support system follows with more detailed descriptions in the separate pages of this section.
Innerspring: As a group, these are the most common types of mattress core and still dominate the industry. There are 4 basic types of innerspring called Bonnell, Offset, Continuous coil, and Pocket coil. While there are many different names for each of them, all innersprings will fall into one of these categories. These mattress cores are suitable for use with any type of comfort layer over them including Latex, Memory Foam, Polyurethane foam (most common), or Natural Fibers. Innersprings have been used for many years, are well understood by the industry, and are relatively inexpensive to manufacture so they remain a popular option. While they can all be made in firm versions that are suitable for a differential construction, there are differences between the different categories that make some more suitable than others in progressive constructions. In best to worst order of their overall ability to take on the shape of a body profile and assist with pressure, they are Pocket coils, Offset coils, Bonnell coils, and Continuous coils. The order is the same for manufacturing cost from highest to lowest although there is a wide variety in each category.
Latex: Latex foam has also been in use for many years but it is enjoying a resurgence in popularity because of its many beneficial qualities when used in a firmer ILD as a support core or a softer ILD as a comfort layer. While good quality latex is among the most expensive of the foams, its wide range of firmness choices and its variety of different feels and qualities in different ILD's and between the two main types of latex, Dunlop and Talalay, make it one of the best choices in a mattress in any layer. Some of its most appealing qualities include its progressive firmness, its resilience, its ability to form itself to the shape of a body profile, and its durability, all of which can be important qualities in a mattress support core. It has the best "technical" qualities of any foam and both main types can be used as a support layer or a full support core with any type of comfort layer and with any method of construction.
Polyurethane (Polyfoam): Also called polyfoam or poly, polyurethane is the most common material used as a comfort layer in a mattress but it is often used as a core material as well. It comes in 3 different grades and while in the highest HR grade it can be a very high quality and desirable material, it is rarely found in this grade in even more expensive mattresses outside of smaller local and regional manufacturers. HD or High Density polyfoam (typically 1.8 lb density or higher or 1.5 lb density in lower budget mattresses) is much more commonly used in mattress cores, particularly in combination with higher quality latex and memory foam comfort layers, and can also be a suitable and durable material in a support core. The lowest grade of conventional polyfoam (less than 1.5 lb density) is not suitable for use in a mattress outside of those that are purchased in the full knowledge that they will not last or are suitable for temporary or occasional use only and the price reflects this. Outside of the highest HR grade which can cost more than innersprings to manufacture and can approach latex in its properties (although to a lesser degree), polyfoam is a lower cost, and often higher profit material that is often used in mattresses selling for more than they should be in the mainstream industry and does not have the same desirable qualities or durability as other higher quality foams.
Airbeds: Airbeds are a mattress category that has become somewhat successful due to advertising and somewhat misleading information rather than a true understanding of its real qualities. Like an innerspring, it is only suitable for use as a support core in a mattress and while it has some features that appear to be appealing on first glance (and which are heavily promoted), they do not fare so well on closer examination or in comparison with other mattress types. Like innersprings, an airbed support core needs an effective comfort layer above it. In general Airbed mattress cores have inflated prices and are less effective as a mattress core than many innersprings, latex, or high quality polyfoam ... in spite of many statements otherwise by those who make them.
Waterbeds: These became popular in the late 60's and 70's and have retained some level of popularity with a core group of believers ever since. The newer "soft sided" versions share some similar principles to airbed cores but are can often be superior to airbeds for support. In some cases, depending on body shape and weight distribution, their pressure relieving qualities can be matched with good alignment although it can be more difficult to combine these qualities than some innersprings, latex, or high quality polyfoam mattress cores with high quality comfort layers. They have seen many design improvements since they were first developed to make up for some of their original shortcomings. Softsided versions can be used with a good quality comfort layer above them or as a complete mattress however like airbeds, they remain a niche mattress style due partly to different preferences, partly to outdated information, and partly to the comfort/support controversy that surrounds them. Their page in this section includes an extensive analysis of their strengths and weaknesses.
While they are commonly thought of as separate "categories" of mattress, memory foam and to a lesser degree natural fibers, are not suitable or found in the support core of a mattress and more information on these and other more "comfort layer specific" materials can be found in the comfort layers section of our website.