Decide what kind of upholstered furniture you want to build. Obtain the appropriate frame from a lumber or furniture supply store, or build your own using kiln-dried hardwood. Use oak, maple or ash wood when building a furniture frame. Join the frame by sectioning wood in the shape of a frame with dowels, to ensure that the wood frame is secure. You will also want to use wood epoxy glue along with the dowels. Clamp frame in place until glue is dry.
Use corner blocks on the frame after it is doweled and glued. Screw blocks into place with a screwdriver to add extra durability. Use center legs on the frame for additional support, and choose thick wood legs in general to attach to the frame.
Add the spring to the frame. Use an eight-way hand-tied spring for sofas and bigger chairs. Attach to the bottom of the sofa with webbing, and tie with twine at the top and through each of the adjacent eight coils to prevent the spring from shifting.
Tie the spring tightly to the frame of the wood by wrapping the twine around the wood and through the center of the coils, pulling tight so that the spring is seat level with the frame, yet not able to sink. Repeat the process until the coils of the spring are firmly attached to the frame. Secure the twine to the frame in strong double or triple knots.
Pad the frame next. Use high-density polyurethane foam wrapped in Dacron for the padding, or choose spring down coils that are in between the padding already. This adds support and extra cushioning.
Upholster the furniture last, using the material of your choice in the color and pattern that is to your liking. Choose a coarser material for sofa cushions, such as tightly woven polyester, or cotton and rayon with acetate, for a softer fabric.
Have the fabric pre-sized after measuring the furniture, or use two to three yards of fabric per piece of furniture, and cut the fabric with upholstery scissors, after taking measurements. Pin the fabric in place with upholstery pins while draped over the furniture to get an idea of the right size. Trim excess fabric away.
Upholster the back of the furniture, pulling the fabric tight as you go along. Staple the fabric at the sides into the frame of the furniture, with a staple gun, pulling fabric tightly as you go up. Make sure that the fabric does not bunch in sections, and bring over to the other side and continue stapling throughout. Do the arms last, trim off any excess material and staple in place.