Different Types of Mattress Support (Core)

August 27, 2021

When we think of a mattress, we often pay the most attention to how soft or firm it is. When we lie down on a mattress, we may describe it as either, "comfortable" or "uncomfortable." With so much attention to the comfort a mattress provides, we often don't stop to think about the support inside.

The support a mattress gives will have the most impact on not only our quality of sleep but also how we perform during our waking hours. Support is the most important factor when considering which mattress is going to be the best for you.

In innerspring mattresses, support comes from the coil system. In a foam mattress, however, there are no coils, so the support systems consists of a foam core at the center of the mattress, and other foam layers. We will discuss the types of coil systems as well as foam cores and latex cores.

Different Types of Mattress Coil Systems

Inside of a Chattam & Wells innerspring mattress

Innerspring mattresses and hybrid mattresses have a coil spring system. Steels coils underneath the comfort layers provide a responsive and supportive base to the mattress. There are four coil systems commonly found in today's innerspring beds:

  • Bonnell

  • Continuous

  • Tied (also called offset coils)

  • Marshall (also called wrapped or pocketed coils)


They each have different benefits and disadvantages and are used in mattresses with different goals - whether that be motion transfer reduction, pressure relief, responsiveness, etc.

Bonnell Coil

Bonnell Coil Spring

The Bonnell coil has an hourglass shape. The thinner middle part compresses with soft pressure, and the rest of the spring provides deep-down support. The Bonnell coil system is the least expensive, and also the least durable. This coil system is typically found in the most inexpensive budget mattresses, as it's a lower-quality system.

They make for good dorm or guest room mattresses, but you should look for another coil system for a bed that will get nightly use. A Bonnell coil mattress will only last about three to five years if it's used every night. A mattress with a Bonnell coil is a good choice for children who'll outgrow their mattress before the coil loses its supportive qualities.

  • Affordable price

  • Least durable (3-5 years of nightly use)

Continuous Coil

A continuous coil system consists of one single piece of steel that's twisted into individual coils. They're connected by helical lacing that runs from the head to the foot of the mattress. The helical lacing helps prevent motion transfer, so you feel less movement from your partner throughout the night.

This system is quite durable, and it provides added support in the center third of the mattress, which is where your body needs it most. A continuous coil system is ideal for those who suffer from lower back pain.

Fun fact: Serta invented the continuous coil system.

  • Single piece of steel

  • Quite durable

  • Supportive to the back

Tied Coil

A tied coil system is comprised of individual coils connected by helical lacing. This design allows the mattress to conform to your body while giving sturdy lumbar support. Tied coil systems provide the stiffest support, so they're also a good choice for back pain sufferers. The construction of a tied coil unit makes it quite durable, so these mattresses often come with long warranties.

Tied coil systems are better at reducing motion transfer than Bonnell coils but not as good as pocketed coils. Those who sleep with a restless partner will feel movement on their side of the bed.

  • Sturdy support

  • Good durability

  • Mediocre motion transfer reduction

Marshall Coil

What are Pocketed Coils?

Also known as: wrapped coils, encased coils, encased springs, or Marshall coils

Pocketed springs are one of the most commonly used construction materials for mattresses. These coils are springs formed from varying types of wire that are compressed within a fabric encasement. It does a better job of conforming to the body than the other systems. Since each coil is individually wrapped, these mattresses excel in motion isolation.

While traditional coil systems have springs that are wired together, the springs in a pocketed coil system are individually wrapped in fabric encasements and perform independently from one another. This design allows each pocketed spring to react as needed, responding quickly to movement and conforming to the contours of your body. This also makes the Marshall coil ideal for use with adjustable bases or foundations.

Since each mattress coil works independently, this system is slightly less durable than a continuous or tied coil. However, the comfort materials in your mattress will wear quicker than the coil system would. So, you'll likely move on to another mattress before the system loses its support.

Pocketed coils, individually encased in white fabric

The recent dual stage coil-in-coil design, found in Stearns & Foster Estate mattresses, is an update on the original Marshall coil design. It includes two separate coils that each work independently. This coil-in-coil design enhances contouring comfort while providing stable underlying support.

  • Good contouring

  • Good motion transfer reduction

  • Compatible with adjustable bases

  • Less durable

Fun Fact: Beautyrest first introduced this industry-altering invention in 1925 and it revolutionized mattress production and construction even to this day.

Pocketed Coils Improve Sleep

Pocketed coils, individually encased in white fabricIt's recommended that most adults receive roughly 7-9 hours of QUALITY sleep per night. If you think lying down and setting your alarm for 8 hours later is enough, it may not be. It only takes a few disturbances to break your sleep cycle and prevent your brain and body from ever entering the deep sleep needed to fully recuperate.

Minimizing these disturbances with a pocketed innerspring system is a great way to greatly improve the quality of your sleep. If you sleep with a partner, individually wrapped coils greatly decrease the amount of movement you'll feel when they shift during the night. This helps you stay asleep, which makes the quality of your sleep better.

Pocketed coil systems also help reduce tossing and turning because they're perfect for pressure relief. The coils can push down under your heavier areas while pressing up against the areas that need more support like your lower back. With a tied coil system, all the coils are grouped together meaning they all compress in an area where you need more support.


Choosing the Right Coil for You

Each coil system has advantages and disadvantages. If you're not sure which coil system is right for you, don't hesitate to call one of our friendly mattress experts at 1-800-455-1052. They'll walk you through the process of picking the right coil.


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Foam Cores

Cutaway of a Sealy mattress with a foam core

Foam cores are made from high-density poly foams. When we think of foams, we usually think of something soft and fluffy, but foams can be very hard. Foam cores in memory foam mattresses are very dense and sturdy so that they can provide the right amount of support to the body. Foam cores in high-quality memory foam mattresses also work to keep each sleeper's body properly aligned during the night.

Even in the softest memory foam mattress, there is a stiff, foam core working underneath the softer comfort layers. While the soft foams provide relief from pressure points and body contouring, the bottom denser layers are what provide support in a memory foam mattress.

That's why sleepers who enjoy extremely soft mattresses (those that range from 8-9 on the US-Mattress Comfort Scale), and those who prefer very firm support (1-2 on the Comfort Scale), can get the kind of support the body needs to wake up feeling well-rested and pain-free.

At US-Mattress, every memory foam and gel memory foam mattress we offer is equipped with a sturdy and supportive foam core. No matter what memory foam or gel memory foam mattress you choose, you can count on getting solid and sturdy support every night you lay your head to rest.


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Latex Cores

Latex mattresses are a popular option for those that like natural materials and a springy feel. Like foam mattresses, latex beds have no innerspring coils, unless they're a hybrid mattress. The support provided by these mattresses comes in the form of a more dense layer of latex.

The latex core will usually be Dunlop latex because this type of process results in latex that is denser on the bottom, from the sediment settling as the foam sets. Talalay latex is usually softer and lighter, so it's more often used to add comfort above the support layers.

Related: Types of Mattress Foams (and Latex)


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FAQs

  1. What is the difference between a Bonnell coil and an offset coil?

    Offset coils have a more square-shaped and are tied together with helical wire while Bonnell coils are circular and tied with spiral wires into rows. Offset coils function more individually, as they are only tied to the next coil, not into rows. They tend to be in more mid-end or high-end mattresses since they're more expensive than a Bonnell system.

  2. What's better - pocketed coils vs continuous coils?

    While continuous coils are more durable, pocket coils are more effective at supporting you in a way that aligns your spine and relieves pressure. They're better at reducing motion transfer as well. High-quality mattresses usually use pocketed coils.

  3. What's the difference between innerspring and encased coils?

    Generally, when someone refers to an innerspring, they are talking about a mattress with any of the coil systems. Encased coils are a specific coil type, also known as pocketed coils or Marshall coils. They're different than a traditional innerspring because they move individually instead of being all connected.

  4. What's the best coil system for a couple?

    Individually wrapped coils provide the most motion isolation but are still very responsive, so a pocketed coil system would be best for a couple. They're also good at accomodating any sleeping position, so it works even if there are different sleep preferences.

  5. What's the best coil count for a mattress?

    There should be several hundred coils in a mattress at minimum, but many have up to a thousand. Generally, more coils provide better sleep, but it's unclear if going much over 500-800 coils provides significantly more benefits. The ideal number of coils would also depend on the type of coil system. A queen size should have at least 400 coils.

Related:What Does Coil Gauge Mean?


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