The Construction of Sofas

Frame

• A sofa's frame is one of the biggest factors in determining how long the piece of furniture will last. The most durable sofa frames are made of kiln-dried hardwood. Kiln drying ensures that the frame will not warp or break as the wood in the frame loses moisture over time, and solid construction with oak, maple, alder or ash is much sturdier than plywood construction. Individual frame pieces should be joined with dowels, and corners should be reinforced with wood blocks.

Springs

• The supporting springs usually follow one of two common designs. Eight-way hand-tied springs are coil springs that are attached to webbing at the bottom of the sofa and tied together at the top with twine stretched in eight different directions. This traditional spring system is labor intensive to manufacture and are generally more costly than sinuous springs. Sinuous springs are S-shaped metal springs that run horizontally from the front of the sofa seat to the back and are more common in contemporary sofa designs.

Cushion Construction

• The simplest and most common method of constructing sofa cushions is to wrap a cushion form made of polyurethane foam in a cotton or polyester fabric covering. These cushions are inexpensive and offer varying firmness depending on the density of the foam used. Innerspring cushions incorporate a system of coil springs within a layer of foam, which is then covered with fabric. Higher-end cushions may utilize down or feathers as a filling material.

Upholstery

• Some synthetic upholstery fabrics are among the least expensive options for finishing a sofa, but many man-made fabrics have the advantage of being durable, stain-resistant, tolerant of exposure to sunlight and flame-retardant. Among natural fibers, linen is the most durable, while cotton is sensitive sunlight and moisture. Wool is stain-resistant and wears well. Leather is tough and attractive but costly.