Understanding Upholstery Construction: What’s Inside Your Furniture

When you sit on a new sofa or chair, you usually notice the style, fabric, and comfort — but not what’s inside. The unseen construction details of upholstered furniture play a huge role in its comfort, longevity, and overall quality.

Every piece of upholstered furniture is made up of several key components: a frame, springs, deck, cushions, padding, and a fabric cover. Each part contributes to the strength, feel, and performance of the finished piece.

The Frame: The Foundation of Every Piece

The frame provides the structure and shape of any upholstered item. If the frame is unstable, the furniture won’t be durable, no matter how fine the fabric or cushioning.

Quality Frame Materials

• The best frames are made from solid hardwood, often kiln-dried to reduce moisture, prevent splitting, and increase strength.
• Common hardwoods include white ash (considered superior), white oak, red oak, American elm, hard maple, and birch.
• Softwoods make poor frame materials because they lack durability.
• Engineered wood and plywood may look less traditional, but their layered construction can actually make them stronger than solid hardwood in key stress areas.

Joinery & Construction Methods

High-quality frames use multiple joinery techniques for strength:

• Double doweling, where round wooden pegs are glued into holes between sections.
• Epoxy-coated staples and gang nails (metal plates with teeth pressed in hydraulically).
• Corner blocks, glued and screwed into place at major joints for added support.

Why Thickness Matters

Strength increases with both width and thickness of the rails. For example, a 1″×1″ beam may support 100 pounds, but a beam 1″ thick and 2″ wide can hold 200 pounds. As a rule of thumb:

• Rails 3″ or wider should be at least 1-1/8″ thick.
• Rails narrower than 3″ should exceed 1-1/8″ thickness.

Manufacturers who cut corners on frame thickness often compromise the long-term durability of the furniture.

Springs: The Secret to Comfort

Springs or webbing are attached to the frame to create elasticity and support. The most common types include coil springs, sinuous (sagless) springs, the Flexsteel ribcage spring system, and modified ribbons for reclining furniture.

Coil Springs

Coil spring upholstery originated in France during the 1700s and became popular in the 1800s. The springs are clipped to the base webbing, then tied to each other and the frame with twine in an eight-way hand-tie pattern — a mark of premium construction. Earning the name “8-way hand tied.”

Tying springs keeps them vertical, evenly distributes weight, prevents shifting, and ensures a consistent, supportive seat. Coil springs create a firm, uniform feel ideal for long-term comfort.

A spring-edge construction raises the tops of the springs above the frame’s front rail, forming a flexible “floating” front edge for a softer seat transition.

Sinuous (Sagless) Springs

Also called no-sag springs, these S-shaped wires run front to back and are attached to the frame with steel clips. Helical springs connect them for stability. Comfort depends on the spring’s thickness, resiliency, and the size of the space between coils.

Webbing Systems

Traditional jute or linen webbing has largely been replaced by synthetic webbing for added strength and consistency. Webbing or solid panels may also serve as the base deck beneath seat cushions.

Flexsteel’s Blue Ribbon-Ribcage Spring System

Flexsteel’s unique design dates back to the late 1800s, when the company used Swiss watch-spring steel — the same steel used in clock mechanisms for its flexibility and strength. The steel actually strengthens the more it’s flexed, giving Flexsteel furniture its signature durability, reliability, and long-lasting comfort.

The Deck: The Foundation Beneath the Cushions

The deck — the area directly under the seat cushions — is padded over the springs or webbing. In well-made furniture, the deck is smooth and even, with no lumps or gaps. Padding should extend fully to the front edge, covering the spring edge or frame completely for both comfort and protection.

Cushions: Comfort You Can See and Feel

Cushions rest on top of the deck and can be loose or attached. Most modern cushions are made from polyurethane foam, sometimes combined with spring units or down alternatives.

Foam Density Matters

High-density foam (2.0 lbs per cubic foot or higher) provides better support and durability. Back cushions often use lower-density or fiber-filled foam for softness, though it can shift or compact over time unless the blocks are baffled/channeled to keep the fiber from falling to the bottom.

Cushion Wrapping

Foam cores are typically wrapped with polyester fiber or low-density foam to create plushness and prevent fabric wear. The wrapping gives cushions a softly rounded, “crowned” shape and fills corners evenly.

What Is Pilling, and Should I Be Concerned About It?

Pilling is a normal characteristic of many fabrics. It occurs when loose fibers on the fabric surface form small balls, or “pills,” due to friction. It’s not a defect and doesn’t mean the fabric is wearing out. It’s similar to what happens when new carpets or sweaters shed excess fibers. Once the loose fibers are gone, the pilling will stop.

To maintain the look of your upholstery during this phase:

• Use a battery-operated fabric or sweater shaver to remove pills.
• You may need to repeat this three to four times, after which the surface will smooth out and stay that way.

Final Thoughts

At Furniture and Things, we know that real comfort goes far beyond the fabric you see. Every quality piece of upholstered furniture starts with strong frame construction, reliable spring systems, and durable cushioning designed to last. That’s why we partner with trusted manufacturers and offer products built with care so that you can enjoy comfort, style, and lasting quality in every room of your home. Visit our 3-acre showroom to experience the difference quality construction makes in the comfort and longevity of your furniture.