What is the density of sofa foam?
What makes a cushion last longer?
Cushion construction is the single most important factor in determining the lifespan (and comfort) of your sofa, couch or chair.
There are three basic types of cushion construction for most couches and sofas sold in the U.S.
- Coil springs
- Many cushions are made using a combination of two or all three of these various constructions.
Foam is the most commonly sold cushion construction.
Foam is available in several different densities. Each foam density is available in a wide variety of different firmnesses.
- Although most people think that density and firmness are synonymous, they are actually very different.
- Most foam suppliers typically stock 4-5 commonly used densities for residential furniture seat cushions ranging from 1.5 to 2.5. The number designates the weight (in pounds) of 1 cubic ft. of foam.
- Each of these different densities may be available from the foam fabricator (the company that actually produces the foam and sells it to cushion or upholstery manufacturers) in 10 or more different firmnesses ranging from very soft to very firm.
- Upholstery and cushion manufacturers typically use only one or two different firmnesses for each foam density that they stock.
- To keep things simpler for their customers, high density foams are often specified with higher firmness ratings.
Foam cushion lifespan is determined by density, thickness and surface area.
Other factors that affect how long a cushion will last include:
- Frequency of use
- Size of the people using the sofa. Individuals weighing more than 250 lbs. can significantly decrease a cushion's lifespan.
Cushion lifespan can be increased by making the cushion larger.
- For example, if a specific sofa is available with either two or three cushions, each of the two cushions should have a longer lifespan than each of the smaller three cushions.
"Firmness" has no effect on a cushion's expected lifespan.
- Since most consumers equate “firmness” with durability, cheap foams are often made “extra firm.” With a low density foam, however, that “extra firm” feeling will not last long.
- Some cushions are fabricated with an inner core of heavier density foam combined with lower density outer layers.
- Manufacturers and retail salespeople often describe these composite foams using the heavier density only.
1.8 is the most common density found in low and mid-priced residential seating. 1.8 density foam cushions are also frequently found in higher priced seating.
- Depending on the thickness of the foam, whether or not it is HR (High Resilience) and how much use the couch gets, a 1.8 density cushion will typically begin to lose its shape and resilience within one year.
- After 3–5 years a 1.8 density cushion will usually need to be replaced. Since replacing cushions is often not simple or cheap many people choose to purchase another sofa when their cushions wear out.
- Lower density foams are typically used for back cushions or padding that goes over the arms or other parts of the frame.
- Higher densities (2.2 - 2.5) can be found on more expensive residential furniture. Thinner cushions (or composite cushions using more than one foam density) may use densities as high as 2.8.
- Composite cushions may use multiple foam layers with a firm high density inner core and softer low density outer core(s).
- Furniture designed for heavy commercial or institutional use may use foam with densities of 3.0 or higher.
The higher the foam density, the more the cushion will cost.
Variations in firmness usually do not affect cost.
The term "High Density Foam" is almost meaningless. It is used in marketing materials to describe virtually any foam from 1.8 density and up.
- In most cases, when a foam is described only as “high density” with no number, it is a 1.8 density foam.
Foam cushion cores are usually anywhere from 4″ - 6″ thick. Most are wrapped with a dacron polyester fiber.
- The use of memory foam as a wrapping has been increasing over the past several years.
The fiber (or memory foam) wrapping is generally 0.5 - 1.0" thick on the top and bottom of the cushion.
- Both fiber and foam fill in the corners of the cover to eliminate uneven spots and wrinkles.
- Softer foam (including memory foams) will also soften the feel of the cushion.
- Fiber wrappings do not affect the feel of the cushion.
4" thick foam cores made with 1.8 density HR (High Resiliency) foam can be expected to begin losing firmness and resiliency (the ability to “bounce back”) in less than 1 year. The cushions may be completely worn out within 3 years.
5" thick foam cores made with 1.8 density HR (High Resiliency) foam will generally last one or two years longer.
Higher density foams (above 2.0) are usually found only in higher priced custom upholstered seating.
- Higher density foams cost more. A three seat sofa with 2.5 density foam cushions may cost $100 - $200 more than an identical couch with 1.8 density foam cushions.
- When new, cushions with different densities can look and feel identical.
HR (High Resiliency) foam is slightly more expensive (and more durable) than non-HR foams.
- HR (High Resiliency) foams have an additional processing that makes them hold up longer than non-HR foams.
- High Density foams (1.8 and above) can also be High Resiliency foams.
- HR foam's additional cost is minimal. Most High Density foams are also High Resiliency.
Actual foam densities will vary during the manufacturing process. A variation of 0.1 is considered normal. A 1.8 density foam may actually be 1.7 or 1.9. Larger variations are not unusual.
- Many couches sold with cheaper (and lighter weight) 1.5 density foam that will deteriorate even more rapidly, sometimes within one year of purchase.
A cushion's overall thickness may or may not be an indication of its durability.
- “Value priced” couches sometimes have bulked up cushions with several inches of polyester fiber wrapped around the foam core.
- Thick polyester fiber rapidly compresses, causing the cushion to lose its shape. Better quality sofas typically use only 0.5″ - 1.0″ of fiber on each side of the foam core.
- Lower quality couches may use up to 3″ of fiber on each side. Thick layers of fiber are a cheap way to bulk up a cushion over the short term. Thick fiber quickly compresses and causes the cushion to lose its shape - often within one year.
Higher priced couches generally use thick higher density, HR (high resiliency) foams with at least a 2.0 density. but preferably higher. 2.5 or occasionally 2.8 is the highest density usually found in top quality residential furniture.
- Cushions fabricated with good quality coil spring construction will usually have a lifespan as long (or longer) than the best (highest density) foams.
Non-removable cushions enable significant cost reductions compared to loose (removable) cushions.
- Most popularly priced reclining furniture is made with non-removable seat cushions.
- There is virtually no way to tell what type of foam is used inside non-removable cushions.
- It is rarely cost effective to replace the foam inside a non-removable cushion.
When shopping for a couch always test the cushions by picking them up. Heavier cushions last longer than light cushions.
Photo shown above is courtesy of Flexsteel.