Introduction: DIY Modern Outdoor Sofa

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This Instructable is how to make a DIY Modern Outdoor Sofa. It is make from cedar 2x4 and 1x4's and can be made with just a miter saw, circular saw, and cordless drill...though it is easier if you have a tablesaw.

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Tools Used (affiliate):

Materials Used:

  • (7) 8′ 2×4 cedar boards
  • (1) 8′ 1×4 cedar boards
  • (3) 12′ 1×4 cedar boards
  • 1-1/2″ SPAX HCR-X Screws
  • 2-1/2″ SPAX HCR-X Screws
  • 3-1/4″ SPAX HCR-X Screws
  • Outdoor spar urethane
  • 1″ rubber feet

Step 1: Build the Sides

Start by laying out the board to match the colors and pick my best pieces.

Next cut parts for the side assemblies from cedar 2×4. Each side needs a 27-1/2″ top, a pair of 22-1/2″ uprights and a 24-1/2″ base.

Build the sides by drilling ⅜” holes halfway through the tops parts on each end. Use 2-½” screws in the holes to join the boards.

Use a 3/8″ plug cutter to cut plugs to fill the holes in the armrest. Install the plugs with glue and sand flush.

Step 2: Build the Base and Attach to Sides

Cut a 2×4 base stretcher to 69″. Flip it and the armrest bases upside down and connect them with 2-1/2″ screws.

Flip it back over and attach the armrests to the base with 2-1/2″ screws through 3/8" holes like earlier. Fill these holes with cedar plugs as well.

Step 3: Build the Seat Base

The base frame is made from 2×4’s and needs a front and back each 69″, two sides at 24-1/2″ and two inner supports at 24-1/2″. Attach the front, back and sides together to form the outer frame

The two inner supports need notches cut in them to hold the 1×4 seat slats. Lay out four notches 3-1/2″ wide by 3/4″ deep on the inner supports. Use a dado blade on the tablesaw or circular saw to cut out the notches on the boards.

Cut two 24-1/2″ cleats to support the outer ends of the 1×4 slats. Rip a 2×4 in half for these or use 2×2 material. For the final seat parts cut four 1×4 seat slats to 66″.

For the inner supports, space them evenly with the center of the boards 23″ from the outer edge. Do the assembly upside down so the top surface will be flush when you finish.

Flip the seat over and attach the cleats to the sides. The slats should be flush with the outer frame so use a scrap 1×4 to set their position. When the scrap is flush, attach the cleats with 2-½” screws.

Now lay the 1×4 seat slats into the notches and attach them with 1-½” screws.

Step 4: Build the Backrest

From 2×4’s, cut four uprights to 21″ with 15 degree angles on the bottom end. The uprights will be connected by 1×4 slats similar to the seat base. Lay out three 3-1/2″ wide by 3/4″ deep notches and cut them with a dado blade or circular saw like before.

Add a taper to the back of the uprights by striking a line 1″ over from the top notch and 6″ down the upright. Cut to the line on the tablesaw or with a circular saw.

Cut three 1×4’s to 69″ long for the back slats. Lay out the uprights with the same spacing as the seat supports and attach the slats with 1-½” screws.

Step 5: Sand and Finish the Parts

Sand everything and apply finish. It’s much easier to work with the large flat assemblies than to try to sand into corners once the sofa is put together. Sand to 150 grit and apply 3 coats of exterior spar urethane.

Step 6: Attach the Seat to the Sides

Put rubber feet on the bottom of the sides before assembly.

Clamp some temporary blocks to the sides to position the seat which should be 12-1/2″ to the top of the seat. Put the seat in place and secure it to the sides with two 3-¼” screws per corner.

Step 7: Attach the Backrest

Put the back in place and join it to the seat supports with a 3-¼” screw through each upright into the seat supports.

On the back side use two more screws to secure the outer pieces together and put another fastener into the back of the inner supports.

Step 8: Add Cushions and Enjoy!

The base cushions are 24″ deep and 23″ wide and the back cushions are 18″ tall and 23″ wide. You can also purchase cushions online or at a local store to fit your needs.

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