How to Build a Modular Sofa

Written by jane smith
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How to Build a Modular Sofa

Called conversation pits at the time, modular sofas were found in nearly every basement in the 70s. Modular sofas consist of two long, pub-backed or toss-cushioned sections with one overstuffed, rolled arm and large, square cushions. Four square ottomans could be pushed against the two long sections when they were set in an "L" shape to make one large, bed-style seating surface. The ottomans could also be used as coffee tables or footrests, or turned into occasional chairs by pulling them in a haphazard grouping near the two main pieces. It was common to throw the cushions on the floor for kids to lay on while watching TV.

Skill level:

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Things you need

  • Carpenter's square
  • Spirit level
  • Table saw with mitre fence
  • 72 feet of 1-by-6-inch stock wood for box frames (2 couches and 4 ottomans)
  • 28 feet of 1-inch-by-4-inch stock wood for back frames (2 couches only)
  • 24 feet of 4-by-4-inch post for box frame support and feet
  • 28 feet by 4 feet burlap gauze for bottom underlay
  • 2 sets 4-by-6-feet sofa springs
  • 4 sets 4-feet-by-4-feet sofa springs
  • 1/2 inch by 40-feet by 5-feet foam padding or egg crate for upholstery underlay
  • Upholstery fabric
  • 2 6-feet by 2-by-6-inch sheets of cushion foam for back support
  • 12 pieces of 3-by-4-feet by 6-inch foam for seat cushions
  • 6 pieces of 3-by-3-feet by 6-inch foam for back cushions
  • 1.5-inch long by 1/4-inch diameter brass wood screws for back frame
  • 1/2-inch long, 1/4-inch diameter brass wood screws for L-shaped wall mounts
  • 3/4-inch long by 1/4-inch diameter screws for couch springs
  • 4.5-inch long, 1/4-inch diameter brass wood screws for post attachment
  • Power drill, 1/8-inch diagonal bit
  • Countersink bit
  • Staple gun

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  1. 1

    Check all posts with a carpenter's square and a level. Make sure they are cut at a 90 degree angle across each end. If they are not, adjust the angle using a mitre fence and table saw. Cut 28 10-inch-long posts from the 4-by-4-inch stock wood.

  2. 2

    Cut 6-inch stock wood into four 6-feet lengths and four 4-feet lengths. Assemble two sofa box frames by placing two lengths of 1-inch-by-6-inch-by-6-feet stock wood inside 2 lengths of 1-inch-by-6-inch-by-4-feet stock wood. Attach sides to front and back pieces using 1 1/2-inch-long-by-1/4-inch diameter brass wood screws every 2 inches beginning at the bottom front corner, through each side and into the front and back pieces.

  3. 3

    Place one post in each corner of the box. Drill 1/8-inch diameter pilot holes at a 45 degree angle through the post and into the frame. Secure using 4.5-inch long, 1/4-inch diameter brass wood screws.

  4. 4

    Turn each couch frame right side up on its legs. Space couch springs every 2 to 3 inches across the frame. Attach couch spring sets using 3/4-inch long by 1/4-inch diameter screws.

  5. 5

    Make the seat cushions from 12 pieces of 3-by-4-feet-by-6-inch foam by covering them with upholstery fabric in complementary or contrasting colours. You will need one 15 1/2-feet-by-5-feet sheet of fabric for each seat cushion. Lay the fabric pretty side down. Make a 3-inch wide fold at each short end of the fabric piece. Iron each fold flat. Stitch across the open side of each fold about 1/4 inch from the edge. Make a second row of stitches 1/4 inch from the first seam, going closer to the fold.

    Fold the fabric over one of the seat cushions so that the two double seams are touching. Fold fabric in along each side as if making a Christmas package and hand stitch the side seams in place. End the side seams when they reach the double seams on the ends of the fabric. Stitch plastic hook and loop tape (Velcro(R)) along the double seams so that the hook side of the tape is facing the loop side. Repeat this step for all of the seat cushions.

    How to Build a Modular Sofa
  6. 6

    Make back cushions from the 6 pieces of 3-by-3-feet by 6-inch foam. Repeat the directions in Step Five, except the fabric will be 13.5 feet long by 4 feet wide this time.

  7. 7

    Fit the 6-feet-by-2-feet-by-6-inch sheets of cushion foam pieces into each back frame for back support. Cut the 1/2-inch-by-40-feet-by-5-feet foam padding or egg crate to wrap up the sides from the bottom of the bottom frame, over the arm, across the springs and down the other side. Cut two extra layers of foam egg crate for each sofa arm. Staple all foam in place. Use a tack hammer to ensure that all staples are flush with the wood of the frame. Cover the sides and front of the back frame with egg crate foam and staple in place.

  8. 8

    Upholster the front, sides and back of the back frame and bottom frame, and the inner sides and arms of each section. Amounts of fabric will vary, depending on ruffling, piping or pleating. You'll need at least about 30 yards of fabric. Build the four ottomans using the same directions and process but using the smaller 1-inch-by-6-inch-by-3-feet boards. Staple burlap gauze to the bottoms of each sofa section and each ottoman.

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