This project covers installing decking on a 45-degree angle.
Installing decking at a 45-degree angle is not difficult. Practice cutting some scrap decking to make sure you can consistently cut a precise 45-degree angle. Measure carefully to see that the first boards are installed correctly, and the rest of the deck will go on quickly.
Cutting the angles
A radial-arm saw or a 12-inch power miter saw is ideal for cutting 2x6 or 5/4 decking. With a 10-inch power miter saw you may have to finish each cut with a handsaw -- a time-consuming extra step. With practice, you can make accurate 45-degree cuts with a circular saw, using a layout square or a jig as a guide. Some circular saws manage this more easily than others; often, the blade guard gets in the way at the beginning of the cut.
Most of a day to cut and install angled decking on a 300-square-foot deck
Power miter saw or radial-arm saw, circular saw, tape measure, chalk line, flat pry bar, chisel, hammer, drill, handsaw, layout square
Making accurate 45-degree cuts, driving screws or nails, cutting with a circular saw
Check that the framing is securely fastened at all points
Decking, screws or nails
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.
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.
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.
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.
If the last piece is large enough, install it as you did the other boards by drilling pilot holes and driving fasteners down through the face of the board. If the piece is small, cut and attach it after making the chalk line cuts. Drill horizontal pilot holes and attach the piece with screws or nails driven into the adjoining deck board. There will be no space between these two boards.