Creating Curves Part 2 of 2

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A curved deck is created by cutting joists to match the curved profile, then attaching a curved rim joist, which can be shaped in one of two ways (see Construction Options). Braces attached to the tops of the joists hold them in place as the rim joist is installed.


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Continue to Step 1


By their nature, curved shapes lend a feeling of tranquility to a landscape. A deck with curved sides tends to encourage quiet relaxation. A curved deck can also provide an effective visual transition between the sharp architectural angles of the house and the more sweeping natural lines of the surrounding landscape.
Curved decks nearly always use a cantilevered design, in which the curved portion of the deck overhangs a beam that is set back from the edge of the deck. This setback distance generally should be no more than one-third of the total length of the deck joists, but longer cantilevers are possible if you use a combination of thicker joists, closer joist spacing, and stronger wood species, such as southern yellow pine.
Note: The curved deck shown on the following pages was built using primarily 4 x 4" posts. Recent changes to some building codes indicate a preference for 6 x 6" posts. Always check with your local building department to learn applicable codes for your deck.
If your curved deck will be high enough to require a railing, we recommend a design that incorporates a circular curve rather than an elliptical or irregular curve. Adding a curved railing is much easier if the deck curve is based on a circular shape.
Curves and Deck Design

Adding curves to your deck is not something you should do on the spur of the moment. Consider the pros and cons carefully before you commit to curves. Here are some to think about:

• Curves can add visual appeal and uniqueness to your deck.
• Curves soften the overall feeling.
• Used wisely, curves have a natural, organic visual quality.
• A curve can be used to work around an obstacle in a pleasing way.
• A curved corner can preserve space below the deck.

• Decks that incorporate curves almost always require more posts and beams, and they make less efficient use of building materials.
• A deck with curves takes at least twice as long to build as a square or rectangular one.
• Curved railings are tricky to make.
• Impact is lessened if curves are overused.
• Curves reduce and constrict deck floorspace.

What You'll Need


Circular Saw
1 1⁄2" deck screws
belt sander


Circular Saw
1 1⁄2" deck screws
belt sander


Step 1

How to Lay Out a Curved Deck

Cut off each joist with a circular saw set to the proper bevel. Clamp a straightedge to the joist to provide a guide for the foot of the saw. On the outside joists where the curve begins, make 90° cuts.

Step 2

How to Lay Out a Curved Deck

Where the bevel angle is beyond the range of your circular saw, use a reciprocating saw to cut off the joists.

Step 3

How to Construct a Kerfed Rim Joist for a curved Deck

Mark the inside face of the rim joist lumber with a series of parallel lines, 1" apart. Using a circular saw or radial-arm saw set to a blade depth equal to 3⁄4 of the rim joist thickness (1 1⁄8" for 2"-thick lumber), make crosscut kerfs at each line. Soak the rim joist in water for about 2 hours to make it easier to bend.

Step 4

How to Construct a Kerfed Rim Joist for a curved Deck

Install a cross block between the first two joists on each side of the curve, positioned so half the block is covered by the square-cut outside joist (inset). While it is still damp, attach the rim joist by butting it against the end joist and attaching it to the cross block with 3" deck screws. Bend the rim joist so it is flush against the ends of the joists, and attach with two or three 3" deck screws driven at each joist.

Step 5

How to Construct a Kerfed Rim Joist for a curved Deck

Where butt joints are necessary, mark and cut the rim joist so the joint will fall at the center of a joist. To avoid chipping, cut off the rim joist at one of the saw kerfs.

Step 6

How to Construct a Kerfed Rim Joist for a curved Deck

Complete the installation by butting the end of the rim joist against the outside joist and attaching it to the cross block. Use bar clamps to hold the rim joist in position as you screw it to the blocking. Note: If the rim joist flattens near the sides of the deck, -install additional cross-blocking, cut to the contour of the curve, to hold the rim joist in proper position.

Step 7

How to Construct a Curved Rim Joist with Laminated Plywood

Install blocking between the first two joists on each side of the deck. Cut four strips of 1⁄4"-thick exterior plywood the same width as the joists. Butt the first strip against the outside joist and attach it to the blocking with 1 1⁄2" deck screws. Bend the strip around the joists and attach with deck screws. If necessary, install additional blocking to keep the plywood in the proper curve. If butt joints are necessary, make sure they fall at the centers of joists.

Step 8

How to Construct a Curved Rim Joist with Laminated Plywood

Attach the remaining strips of plywood one at a time, attaching them to previous layers with 1" deck screws and exterior wood glue. Make sure butt joints are staggered so they do not overlap previous joints. For the last layer, use a finish strip of 3⁄8" cedar plywood. Where the finish strip butts against the outside joists, bevel-cut the ends at 10° to ensure a tight fit.

Step 9

How to Install Decking on a Curved Deck

Install decking for the square portion of the deck, then test-fit decking boards on the curved portion. If necessary, you can make minor adjustments in the spacing to avoid cutting very narrow decking boards at the end of the curve. When satisfied with the layout, scribe cutting lines on the underside of the decking boards, following the edge of the rim joist.

Step 10

How to Install Decking on a Curved Deck

Remove the scribed decking boards, and cut along the cutting lines with a jigsaw. Install the decking boards with deck screws, and smooth the cut edges of the decking boards with a belt sander, if necessary.



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