Build a DIY Upholstered Sofa: The Frame Plans

How to Build a Sofa

In Part One of the DIY Upholstered Sofa series, I outlined the supplies and materials needed to build the sofa. In this post, Build a DIY Upholstered Sofa: the Frame Plans, I give step-by-step instructions (in plan form) to build a super-solid base for this fabulous sofa! So, let’s get started…

For this sofa, I built the same DIY legs I made for the upholstered chair. I figured this way, it would tie both furniture together, plus the legs are super-easy to build! The seat frame is constructed using 2x4s with 2x3s as supports under the seat, and the back frame is constructed out of 2x2s with a 3/4″ plywood layer over it. The pieces are joined together (AFTER upholstering) with 1/4″ x 4″ washer head lag screws for the ultimate stability! I used a pocket hole jig to connect the frame pieces to the legs, and countersunk screws to assemble the back frame.

To Build the Seat Frame:

Step One

Cut the 2×4 pieces for the frame.  With the pocket hole jig set for 1-1/2″ material, drill pocket holes in each end of each piece, including the 2×3 seat supports and the 2×4 back support. Assemble the seat frame as shown, using glue and 2-1/2″ screws.

Step Two

Secure the 2×4 back support piece to the sides of the frame using glue and 2-1/2″ screws. This piece is a sort of “stop” for the back because the back leans back 15°.

Step Three

Secure the 2×3 seat supports to the front of the seat frame and the back support, with the bottom edges flush using glue and 2-1/2″ screws. These pieces provide support to the frame but are not as tall so they won’t be felt through the seat webbing (in the next post!)

To Build the Back Frame & Base:

Step Four

The frame pieces are all cut a bit differently, some with angles at the top and bottom facing in different directions. Looking at the drawing below:

• The longest top piece will be cut at 62″ with a 22.5° angle at each end (the angle will help form the rounded corners on the back).
• The next short pieces in blue are also cut with 22.5° angles at each end.
• The outer pieces in coral are cut as a left and a right with a 22.5° angle at the top and a 15° angle sloping toward the front (this will allow the back frame to lean).
• The center pieces in green will have the same 15° angle sloping toward the front.
• And last, the lower pieces in purple will have a 15° bevel cut along one long end of each piece.

Assemble the frame using glue and countersunk 2-1/2″ screws. (Have questions? Let me know!)

Step Five

Cut the piece for the back base. Cut the corners and notches using a jigsaw. Secure the base to the back frame using glue and 1-1/2″ screws through the base into the back frame.

DO NOT attach the back frame assembly to the seat frame – this will be done after the upholstery is complete! Stay tuned because the next post, Part Three, is all about adding the seat webbing and the upholstery!

Have questions so far about how to build a sofa? Leave a comment below!

Originally posted 2019-10-25 08:00:57.