How to Build an Angled Deck

Get a gorgeous 45-degree deck design with our step-by-step building instructions.

Project Overview
  • Working Time: 3 days
  • Total Time: 3 days
  • Skill Level: Advanced

Having a deck in the backyard opens up so many opportunities for your family. Enjoy dinner in the breeze, or gather with friends and family under the stars. But before you can make those lasting memories, you need to build your outdoor room! Below, we show you how easy it is to build an angled deck. This gorgeous design is perfect for a beginner and looks beautiful. Get started this weekend!

What You'll Need

Equipment / Tools

  • 1 Power miter saw or radial-arm saw
  • 1 Circular saw
  • 1 Tape measure
  • 1 Chalk line
  • 1 Flat pry bar
  • 1 Chisel
  • 1 Hammer
  • 1 Drill
  • 1 Handsaw
  • 1 Layout square


  • 1 Decking
  • 1 Screws or nails


  1. Prep House

    adding 1/4" plywood strip to deck

    To help maintain a straight line near the house, temporarily attach a strip of 1/4-inch plywood against the siding, on top of the ledger. Make sure the screws you use to fasten the strip are above the decking thickness so you can remove them after you install the decking.

  2. Cut Boards


    Choose two straight boards and cut one end of each at a 45-degree angle. A 10-inch power miter saw will not cut all the way across the board. Complete the cut with a handsaw. If you are experienced using a power miter saw, lift up on the forward edge of the board to finish the cut.

  3. Install First Boards


    Set the two boards on the joists with the mitered ends pressed against the spacer strip. Measure from the corner to the edge of the decking in both directions. When the two measurements are equal, the decking is at a 45-degree angle to the house.

    Check the first board for straightness and fasten it to the joists with nails or screws. You may drive all the fasteners as you go, or drive only a few at this point and snap chalk lines to line up all the other fasteners.

  4. Continue Laying Boards


    Attach decking by driving two fasteners wherever a board intersects a joist. Insert a spacing jig between the boards. An automatic-feed screwdriver makes the job go quickly. Set the nail or screw heads slightly below the face of the decking.

  5. Mark Overhang


    To mark the decking for a 1-1/2-inch overhang, hold a piece of 2x lumber (which is actually 1-1/2 inches thick) under the decking as a gauge to mark both ends of the cut.

  6. Make Chalk Line

    pulling chalk line to level deck

    Give your chalk line box a good shake to make sure the line is well-loaded with chalk. Hook the line onto a nail or screw driven partway into the side of one of the marked boards. Be sure to pull straight up when you snap the chalk line.

  7. Cut Edges


    With clamps or deck screws, temporarily attach a straight board to the decking to serve as a guide for cutting along the chalk line. Cut the line with a circular saw.

  8. Bend and Fasten


    If a decking board is bowed, you will need to bend it into place. Insert spacers and fasten one end of the board. Then move along the board, straightening it as you go. Where a board needs persuading, drive a fastener partway into the board, push it into position, and finish driving the fastener.

  9. Pry Board


    If pushing does not do the trick, dig the point of a chisel or pry bar into the joist, right up against the decking board, and pry the board into position. If a board is so badly bowed that neither of these techniques works, replace it with another one.

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