- Once the frame is constructed, a spring system is installed to support the seating area. Furniture manufacturers employ two main types of spring support systems: sinuous springs and eight-way hand tied springs. When the spring system is finished with a top layer of padding, it is commonly called the "seat deck".
- Most manufacturers offer either sinuous springs or drop-in-springs as their standard, depending on how they make their furniture. Both types affix to the frame to support the seat deck. Sinuous springs have a formal, very firm "sit" and only move in the up/down direction. In contrast, eight-way hand-tied springs can move in many more directions.
- Sinuous springs are heavy-gauge steel springs that have been heat formed into continuous "S" shapes. They are cut into lengths and affixed to the frame. Eight-way hand-tied springs have a wide range of movement providing a very even and individual "sit", because they move up and down and side to side. In the construction of these systems, the craftsman individually ties heavy gauge coils from front to back, side to side and diagonally (eight ways) to provide the highest level of quality, comfort and durability. This process costs more because it is time consuming and can only be done by hand.