How-Tos

What Lies Beneath: Sofa Construction

Take a good look at a sofa’s frame, seating support and filling for a good idea of its comfort and durability. It all works together: a quality frame supports the seating which is enhanced by the filling.

Frame

Look for a frame made of kiln-dried hardwood (oak, maple, poplar, etc.); an ideal material, it retains its shape and stability over the long-term. Soft pine is an inexpensive choice, but doesn’t offer the durability of hardwood. Beware of green (wet) wood that can shrink or crack; knotted wood that can crack; plywood and particle board (especially when joined by staples) that will not last. If you do choose a plywood frame, however, ensure that it has 11–13 layers of plywood and not fewer.

Examine the joints, which should be glued, dowelled, and screwed. Reinforcing blocks in the corners are a plus as they provide additional strength and support.

Seating Support

Test the quality of the seating support before you buy. If the seat sags, keep on looking. But if there is good support in the seat and in the back, you may be onto something.
Check for eight-way hand-tied springs, which are connected with a strong twine, passing front to back, side to side and then diagonally in both directions for maximum support.
An alternative is sinuous spring construction where S-shaped springs run from the front of the seat to the back and wires cross from side to side. Sleek and compact, this system is ideal for tight spaces.

Web suspension is another option, although it isn’t necessarily the best choice. Bands of webbing cross the seat and back and attach to the frame to make a platform for cushions. If used alone, web suspension doesn’t provide strong support, but when used in tandem with a tensioner to fasten the webbing to the frame, it offers satisfactory support.

Filling

Time to check out what’s inside the cushions. Are they firm, resilient and snug-fitting? Filling choices are numerous: down on its own or in a blend is soft, but expensive and high maintenance. High-density polyurethane foam provides firm support, but must be of high quality or else they will break down quickly. Springs surrounded by high-density foam and wrapped in down pads are strong, resilient, supportive and soft.

As you may surmise, quality comes with a price. But while a well-made sofa may require a larger initial investment, you will enjoy a fine piece of furniture for years to come.