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The Geometry of Comfort
FEATURE STORY
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by Becky Miller

Looking for the seating angle that delivers the highest level of comfort is a complex mission. Part engineer and part fashion designer, the sofa designer must mix art and science to achieve the right level of comfort within the context of the consumer’s preferences du jour. The seats on futon frames slant backwards; all of them do it to varying degrees. This is a fact on which all can agree, but why is this so?

The details behind this reality are the essence of this story. Why futon frames were designed this way? How does the seating angle on a futon compare to the seating angle on a traditional sofa? How does the slanted seat affect consumer perception of the futon product? How does the angle affect comfort? In Futon Life’s intensive look at the seating angle issue, we will explore these questions and more.

Comfy Bums

The two fundamental reasons for a futon frame’s slanted seat deck are ergonomics
(what makes a seat comfortable?) and physics (how does one keep a flat mattress in a
folded position?).

Anyone whose backside has gone numb from sitting on a hard, flat surface too long understands the importance of ergonomics in seating design. Our bodies know that no comfortable seating surface is flat.

An angled seat is important because of the way a chair or futon exerts force on the human body. As a sitting body presses down on a surface, so the surface pushes back against the body. How and where the upward force of the cushioning focuses on the body makes a big difference in comfort, said Pete Dodge, a furniture designer who has been involved in the futon industry from the beginning. “There are a couple of spots that should not bear the weight of the body–behind the knees where the tendons are and at the base of the spine. No successful chair puts [pressure on] either place.” Rather, the base of the thighs is the part of the body best suited for bearing body weight and the force of the chair. “You carry your own upholstery with you,” Dodge joked.

The angle that makes a seat comfortable comes either from a cushion or from the actual angle of a hard surface. “When you sit on a Futon cover, your back and tailbone sink in and the weight is transferred to the thighs,” Dodge said.

“Foam absorbs the shape of your body,” said Ron Massey, inventor of the first bi-fold futon frame and owner of Horn dove. Therefore, a hard surface has to mimic the shape of a sitting body in order to offer that same feeling of comfort.

“When you consider the softer cushion on a traditional futons, you have to realize that the way a person sinks into the cushion causes them to lean back a bit,” said Alan Bowden of KD Frames. A firmer futon mattress doesn’t sink as much, “so the leaning back comes from the angle of the frame.”

Dodge elaborated on the same idea. “There was no ‘sink’ in the old, all-cotton futons, so the frame was designed with the slant. Chairs make up for having no cushion by having an angle. Even a hardwood dining room chair slants back. The slant puts weight on the inside of your thighs. Chairs that are designed for you to sit on for a long time are shaped the way you would sink into foam. The thinner the pad, the more the futon frame angle has to make up for it.”

A reclined position is important for both comfort and health. Herman Miller, the company that designed the Aeron chair, has conducted extensive research in the area of seating comfort. They found that most people, regardless of gender, height and weight, prefer sitting in a reclined position. In one study, “All sitters chose substantially reclined postures, with backrest angles averaging 25 degrees from vertical.”1

If vertical is considered 90 degrees, the subjects preferred an approximately 115-degree angle. Harvey Bigelow of Harvey Bigelow Designs pointed out that a backward-angled seat helps people to slouch less. Herman Miller also found that a reclined position is better for back health: “When a person sits in a chair and uses its reclining backrest, disc pressure drops by as much as 20 percent.”

Go to the Mattresses

Angled futon frame seats also work to hold the futon mattress in place. “The mattresses remember that they were made flat,” Dodge said, and they resist being folded.

The angled frame is becoming more important in restraining mattresses that are thicker and more resistant to folding than the original soft all-cotton mattresses. Massey said that the balance of importance of these two issues–seating comfort and mattress positioning–has shifted over time. Perhaps it was a 60-40 balance at the beginning of the industry, weighted toward the comfort issue, but now that futon mattresses contain very resilient materials, it’s more of a 40-60 balance, weighted toward keeping the mattress in place.

Geometry, Algebra and Trigonometry...Oh, My!

Armed with tape measure and protractor, I visited both a furniture retail superstore and a bedding specialty store to measure and compare traditional sofas and futons.

I made some comparisons using the following criteria.

Seat deck angle refers to the angle of the seat in relation to the ground. This is measured up from 0 degrees.

Back deck angle means the angle of the back deck in relation to the seat deck. This is also measured up from 0 degrees, with the seat deck being considered 0 for this measurement.

Seat height is the measurement from the ground to the top of the seat deck. I considered several measurements under this category–the ground to the top of the seat deck without a cushion, the ground to the top of the cushion, and the heights at the fronts and backs of the seat decks.

Seat depth is the measurement of the seat deck from front to back, along the angle of the seat deck.

Research from Herman Miller indicates that most people prefer to sit reclined at a 115-degree angle. These Futon Life findings show that many sofas and futons are designed with similar angles.

My measurements showed that the angle in a futon frame is very similar to the angle in a sofa frame. The big difference is the orientation of the frame opening in relation to the hinge point (see illustrations below).

 

 

As I started researching this story, I expected to find that the back deck angle of a traditional sofa is 90 degrees. This is actually far from the truth. While sofas have virtually no seating angle (the seat of a sofa runs parallel to the ground), the average back deck angle of a sofa is 113 degrees.

I also expected to find the back deck angle of a futon much more obtuse than that of a sofa. In fact, the average back deck angle of a futon is 100 degrees. The average seat deck angle of a futon is 12 degrees. Adding these two measurements together totals 112 degrees, which means that the angle measurement from a line parallel to the floor up to the angle of the back deck on a futon is almost exactly the same as the back deck angle of a sofa (see illustrations above).

The height of the seat at the front of a sofa, including the cushion, averages 19 inches. The height of the seat deck of a futon, including an eight-inch mattress, averages 21 inches. This means that the fronts of the seats of many futons are actually higher off the ground than the seats of many sofas.

The seat depth of a traditional sofa, measured with both back and seat cushions in place, is about 21 inches. The seat depth of a futon sofa with an eight-inch mattress on the frame is the same: about 21 inches.

The futon seat-depth measurement can be affected by the thickness of the mattress on the frame as well as where the futon mattress is folded. Mike Gallawa of Night and Day pointed out, “You can adjust the position of the mattress on the frame to accommodate different heights of people by varying how much mattress sticks off the front of the frame.”

Several of the futon frame manufacturers I interviewed mentioned the importance of folding the mattress off-center rather than down the middle. “The seat should be shallower than the back deck,” said Gallawa.

The height of the back deck on a sofa is about 22 inches. On a futon, the back deck is about 27 inches. This is one of the biggest visual differences between sofas and futons.

Changes Over Time

Futon frames used to be more steeply angled than they are now. Bigelow pointed out a few general changes that have occurred in frame design. “The futon industry has decreased the angle significantly over the years. Sitting height has come up as well–it’s now about the same as a sofa. Futons are at least three inches higher off the floor than they used to be.”

Some futon frame manufacturers have changed their frame designs little, if at all, over the years. Others have tried various innovations to make futons look and feel more like traditional furniture.

“I didn’t like ‘the black hole’ where you sit down and sink back and have trouble getting up,” said Mike Gallawa. His designs for Night and Day changed the angle of a typical futon frame and made their frames more like conventional sofas.

Some companies have developed frames that convert to three different positions (sofa, lounger and bed) instead of the standard two (sofa and bed).

Said Janet Moran at Bedworks, “In our frame design, we raised the hinge point–where the seat and back join together–two inches. Also, our ‘dual position’ frames allow for different comfort levels. In the second position, the seat slides forward two inches, putting the hinge point at about the same place, but the back and seat are more obtuse, putting the back in more of a lounge position.”

Elite uses “click-clack hinges” of their own design so that their futon frames also offer three positions.

The Future of Futon Frame Design

As we have explored in this article, the angled seat on a futon sofa has many benefits, for both health and comfort. The angled seat also prompts some questions.

How does the slant affect ease of getting up? Although sofas and futons have similar angles of recline, does the difference in seat deck angle make it harder for older consumers to get up from a futon than from a sofa? Several people I interviewed for this story told me that this is not really a problem because futon sleepers are not marketed to older demographics.

However, as Futon Life’s recent survey showed, consumers aged 65 and up are entering the futon market in greater numbers than ever before. An angled seat may be a turn off
for that demographic, and if the futon industry wants to attract these buyers (who are furnishing smaller homes or even vacation homes), this issue merits attention.

What is the best way to fold the mattress? We confirmed that the futon mattress should not be folded in the middle. It should be folded off-center so that the portion of the futon on the seat deck is shorter than the portion that rests on the back deck. But, Ron Massey pointed out, “Futons can’t fold at a place where there’s no tufting, so futons always want to fold in the middle.” The way tufting has typically been done, with a line of tufts right down the middle, affects a futon’s ability to fold off-center. Consumers have to go through the process of training a mattress to fold a way it doesn’t naturally tend to fold.

How can we make the futon sofa look more like a regular sofa? Futons still don’t look like traditional sofas or other typical pieces consumers place in their formal living rooms. “The looming back rest is a problem,” Dodge said. “It’s disproportional.” The slanted seating deck is a particular giveaway. Is this a visual turn off for consumers who like the benefits of a futon sofa, but can’t get over the way it looks?

The Big Difference

In summary, the big seating-angle difference between futons and sofas is the 12-degree angle of the seat deck on a futon. However, this decline compensates for the fact that the futon is less “squishy” than a sofa cushion. When a person is sitting down, there is really little difference between the way the body is positioned on a sofa vs. on a futon.

“The ultimate goal of today’s futon is to come out of the back room and into the front room, and to do that, the futon has to feel like a comfortable sofa,” Bigelow said. As futons get closer and closer to feeling like sofas, perhaps the issue is also that futons need to look like comfortable sofas.

In the summer issue of Futon Life, we will continue to explore the various aspects of the seating angle story. We will talk with consumers and try to reach an understanding of what it is that sets futons and sofas apart in consumers’ minds (and eyes).

Do you agree? Disagree? Have another way of looking at this issue? Please email me with your thoughts and any ideas that should be addressed in Part II of the seating angle saga.

FL

 
 
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