A sofa is made in two parts---frame and upholstery. The frame supports the upholstery and the weight of those who use the sofa. Although it's important to know what the sofa will look like in its final appearance, creating a plan for building the frame is arguably the most important part of building a sofa. Sofa building plans are not always easy to locate but frames are everywhere. A little ingenuity can produce an original set of plans.
Design The Sofa
Decide what the final look of the sofa will be. Collect photos of similar sofas or find actual sofas that are close in style. Sofa manufacturers often have catalogues or specification sheets that give sizes, dimensions and other pertinent information about their products. This information is a place to begin building one from scratch. Some sofas are very detailed and need clear working plans, a materials list and cutting diagrams. You can find plans for building a mission style sofa n the book "Arts And Crafts Furniture" written by Wood Magazine. A quick and easy sofa building plan can be found in "How To Make 2x4 Furniture For Indoors And Outdoors" by Mark Baldwin and Family Workshop Inc. The New Yankee Workshop is another place to find detailed furniture building information.
Plan The Frame
Frames are very basic and give the upholsterer the skeleton from which to build curved arms and plushy back cushions. Reuse an old or unwanted sofa frame to create an accurate frame design. The frame can be reused in whole, dismantled, added to or copied. When copying an existing frame, use the original frame parts as templates, adding or subtracting to create a new plan. Other places to find frames are salvage stores and garage sales. Frames are sold by furniture makers without upholstery but can be expensive and somewhat proprietary, meaning the furniture maker will stain and upholster the purchased sofa frame and not allow the frame to leave the premises bare (bare frames are easily copied). Furniture makers often sell catalogues of their available frames.
Find Frame Materials
Wood for a sofa or chair should be strong. Kiln-dried hardwoods are less likely to crack or respond to humidity and weather changes because the moisture in them has been reduced. The wood must be able to hold upholstery structures like jute webbing and coil springs. Birch, oak and hickory are kiln-dried, domestic hardwoods. Consider exotic hardwoods for exposed features like bases, arms, legs and decorative devices. You can purchase furniture legs in metal and wood from furniture accessory makers, woodworkers and furniture hardware manufacturers.