The Essential Parts of a Sofa Diagram

Terms to Know for Each Sofa Style

Types and Terminology of Sofa Parts

The Spruce / Xiaojie Liu

A sofa is made up of many different parts, and every variety creates a distinct look and feel. When choosing a sofa for your home, knowing all the various parts of sofa and couch models, the names of each main part, and its variations can help you describe the style you want to a salesperson or designer. It's also important when judging the quality of a sofa's construction.

Along with learning what the different parts of sofa construction do and are called, it's helpful to take a look at its interior construction. The quality of your sofa depends heavily upon the parts and materials used inside: Hardwood frames, seating support, and the type of cushion filling used can all make a great difference in both comfort and durability over time. These interior parts are wrapped in upholstery (usually fabric or leather) that covers the exterior.

Sectional sofas, in particular, are broken up into individual sections for each side (which can be rearranged in modular designs). A sectional comes apart either by sliding each piece or by disconnecting the screws or bolts that hold them together. The pieces of a sectional sofa may feature a corner wedge, chaise, or recliners in addition to basic components like a loveseat or full-length couch section. Some sectionals may have long chaise lounges, but the longest part of a sofa is usually its width from arm to arm.

Here, learn what the parts of a sofa are called to determine the best type and style for your space.

Curved tufted arm of sofa

Morse Design

Sofa Arms

The arm of a sofa may be called several different names depending on its style, and each type of sofa arm has a different purpose. The arms define the ends of a sofa and play a critical role in the overall look and function of the piece.

  • English arm: An English arm is low and set back from the front edge of the seat. English arms are low-profile and suitable if you like to take naps on your sofa. They are also good for small spaces, as they don't project beyond the body of the sofa.
  • Pleated arm: The front part of a pleated sofa arm is upholstered in fabric that is continued from the inside of the arm.
  • Rolled arm: A very common traditional shape for sofa arms, a rolled arm curves outward. Although comfortable for lounging and reading, rolled arms do take up extra space and should be taken into account when measuring a sofa.
  • Lawson arm: A Lawson arm is a low-profile, modestly scaled version of the rolled arm.
  • Square arm: Also called a box arm, a square arm gives a modern, tailored look, with straight lines and angles. Square arms are useful for entertaining, as they can serve as seats. However, they are not as comfortable as rolled arms for lounging.
  • Tuxedo arm: Tuxedo arms are slightly flared arms that have the same height as the sofa back.
Sleek back sofa

Nile Johnson Interior Design

Sofa Backs

Sofa backs can vary in height, shape, and cushion material and are integral to the style and comfort level of a sofa.

  • Attached back: Attached back cushions are fastened, clipped, or sewn to the back of the sofa. The advantage is that they don't move around, and you don't have to worry too much about keeping them in shape.
  • Camelback: This is a traditional sofa back that is shaped much like a camel's hump, raised in the middle and sloping down lower at the ends. It often imparts a formal look.
  • Channel back: Deep vertical grooves on a tight back are the distinguishing features of a channel back.
  • Loose-cushion: Loose cushions are separate from the sofa back, as opposed to attached back sofas. This allows for covers to be easily removed for cleaning.
  • Curved back: The back of a curved-back sofa curves all the way around so that it forms one solid piece with the arms, which are not attached separately.
  • Pillow back: A pillow back sofa has more pillows than seat cushions, and therefore a softer feel. This style offers comfort that can also be adjusted by moving the pillows around. However, it does require more upkeep to keep the pillows in place.
  • Tight back: A tight back on a sofa is upholstered but does not have loose cushions. The back has a firm feel and can provide a clean, tailored, and formal look.​
  • Waterfall back: A waterfall sofa back has two or more vertical layers of gathered and billowing cushions that are attached to the back.
Gray couch in black and white room

Maite Granda

Sofa Seats

The right feel of a sofa seat is critical to your comfort and enjoyment during use. The parts of a sofa cushion can be designed to create separate seats or as individual single-seat or tight-seat styles.

  • Cushioned seat: A cushioned seat is usually made up of two or three cushions. Since these cushions are made to support the weight of the sitter, they are usually firmer than back cushions. The cushions may be square or rectangular, depending on the number on the seat. Sometimes the end cushions are T-shaped to accommodate the arms. Cushioned seat covers are typically removable.
  • Single-cushion seat: Some sofa seats feature a single cushion. This is also called a bench seat. A single-cushion seat offers a tidy, minimal look that also can be combined with a pillow back, which is more about casual comfort than minimalism. When you sit on one end of a quality single cushion, it should not rise up on the other end.
  • Tight seat: Sofas that have no separate seat cushions are often called tight seats. This style can be found both on traditional and modern sofas or sofas with wood frames. It generally conveys a formal look.
Colorful patterned room with green sofa

Studio London Co.

Sofa Construction

There are various parts of sofa construction that make up its internal structure. These are largely responsible for the longevity of a sofa.

  • Deck: The deck is the surface that lies directly underneath the seat cushions.
  • Down-proof ticking: Ticking is the inner lining of a cushion, usually tightly woven, that helps keep tiny down feathers from moving to a cushion's exterior.
  • Eight-way hand-tied springs: Tied springs are connected to one another with strong twine that runs front to back, side to side, and diagonally in both directions. This construction interconnects the springs for durability and even support.
  • Filling: Filling may be foam, down, or padding that is used to make the sofa comfortable.
  • Frame: The frame comprises the bones of a sofa, which determines not just the shape but also the quality. High-quality sofas have kiln-dried hardwood frames with strong, reinforced joints.
  • Plinth base: Instead of conventional legs, a plinth base is a box-like base often found on contemporary sofas.
  • Webbing: Webbing consists of interwoven strips of synthetic material attached to the wood frame of a sofa. It is typically used in place of support springs.
  • Sofa bed frame: Some sofas can fold out to serve as sleeping areas. Inside a sofa bed or futon, a foldable bed frame rests below the seating or cushions. When the sofa is being used as a seat, the spring-loaded bed frame is usually hidden by the exterior frame of the couch.