While a right-angled deck is difficult to get right, curved decking requires even more patience and building techniques.
In this example, we’re building a deck next to existing curved concrete steps. We’ll show you, step by step, how to install curved decking with the most efficient and effective methods we’ve found.
How to Install Curved Decking: Step by Step
Step 1: Measure for the First Outer Curved Floorboard
We recommend starting with the outer curved floorboard before laying any other decking.
Starting with the outer curved board gives you enough space for effective mounting rather than having to taper it off into a tiny point. Second, it can be hard to eyeball what is perpendicular when you’re looking at a curve. Aligning and laying this first board will improve the parallel nature of the entire deck floor.
First, run a chalk line from your house or the edge of your deck to the other edge of your deck. The chalk line should be perpendicular to your deck floor joists. As the starting point of your entire deck floor, this line is critical in keeping your floorboards parallel.
Rip off several feet of wax paper. (The kind used for baking.) Align the edge of the wax paper with the chalk line (it should be out about 5” or 6” from the top of the curve) and tape it into place, so it runs straight.
Keep the wax paper as flat and taut as possible, but don’t pull it tight, or the tape won’t stick well.
Use a dark permanent marker to trace the edge of the curve. Keep the line precisely spaced along your concrete. If you start your line at the point of the concrete where it begins to curve down toward the ground, maintain that point all the way down your line.
In this example, we drew the line about 1/4″ away from the concrete edge, but we maintained that same distance along the curved line.
Cut your wax paper along the line you just drew.
Before you remove your wax paper, ensure the top is aligned with the edge of your deck (in this case, the house wall). We had to tape a couple of inches of wax paper on the top for precise alignment.
Do this so you can align the wax paper along the top end of your board.
Step 2: Cut Your First Curved Deck Board
Tape or hold the wax paper onto your board, aligning the top and straight sides. It’s important to consider the amount of board you’re leaving intact. We recommend you leave, at the very least, 1” thickness all the way to the top. A little more is better if you can.
It’s a balancing act, though, because you want to take care of as much curved edge with one board.
Install a new blade into your jigsaw if it’s not sharp. You don’t want the jigsaw to chew up your curved edge.
Use a jigsaw to carefully cut along your curve.
If you missed part of the curved line on the first pass, make a second.
A jigsaw tends to wobble as you go, which can result in your curved line having some bumps. While you want to cut along the curved line, be aware that small imperfections can be fixed with a smoother jigsaw cutting.
Dry fit the board to your curve. Make any adjustments needed. For example, if the gap between the board and the concrete is too great, consider cutting an inch or two off the top of your board to bring the whole thing in closer. You can sand out wavy sections if needed.
Step 3: Sand Off Any Roughness
When the board fits in the curve, sand off the rough corner. Don’t get carried away, though – you don’t want to change the curve.
Lay the board where you want it. We recommend leaving a slight gap between concrete and wood for drainage purposes.
Align the curved-cut board with the chalk line you made at the start. Make sure the curve still works at all parts of the concrete connection.
Step 4: Install the Board on the Curved Side
We’re going to be using Camo brand deck screws (2-3/8” for 2×6 redwood deck floor boards) since we’ll be using Camo deck spacers to install these curved pieces.
With the chalk line alignment precise, it’s time to install the curved edge of your redwood board.
With a helper holding the board in place, predrill (we recommend a 7/16” bit) at a sharp downward angle on the parts of the curved board that lies over joists.
Then install the Camo screws into the predrilled points.
Next, throw a couple of screws onto the concrete side of the board. Don’t get carried away, you don’t need these every few inches.
Predrill and screw into the point of the board that separates (curve-wise) from the concrete into the wall-mounted deck frame. Then do the same at the top end of the board. Depending on the length of the curve, you might want to install another one in the middle (if it’s several feet long.)
With the curved part of your board installed, it’s time to turn our attention to the bottom (flat) portion of the board.
Step 5: Attach the Board to the Joists
Work your way, joist by joist, down the length of your board toward the edge. Check for alignment with your chalk line EACH TIME you attach the board to a joist.
As your first deck floorboard, this one has to be perfectly parallel and aligned. It can’t be overstated how important this is to the outcome of your deck.
On each joist, attach your Camo deck spacer by pulling the lever, sliding the guides over the edges of your board until the spacer is flush with the board, and releasing the lever to clamp it in place. Then install the screws.
The beauty of this tool is that the screws go in at an angle, a little below the top of your board. It creates a very secure attachment while being close to invisible.
So, let’s take a closer look at the Camo deck spacer. Install it with the lever so it is directly over and parallel to the joist board.
Install the screw all the way down until the Camo drill bit stopper touches the deck spacer. In other words, until it can’t screw in anymore.
Then, without moving the deck spacer, do the same thing through the screw hole on the other side of the deck spacer.
Remember that on the outer deck frame, where you doubled up your pressure-treated lumber boards, you’ll need to attach the deck board to both framing boards on both sides.
Step 6: Repeat the Process for Each Curved Board
Moving inward and down along your curve, use this same wax paper/sharpie method for every board. Be sure to mark, cut, and install each board before moving on to the next one.
Helpful Tips for Installing Curved Decking
When installing the subsequent boards along the curved concrete, we found this to be helpful: At the innermost possible joist, place the Camo deck spacer between the boards themselves. Then, pound in a wooden shim to maintain spacing between the concrete and your board while you predrill.
When you predrill, do so over a joist or a frame board.
Keeping the shim and deck spacer in place, predrill all the points you’ll need.
Due to the placement of the joists and frame, three holes were predrilled for the end of this curved board.
Install the screws with the deck spacer and shim in place for as long as possible. If you have to move the deck spacer to get a screw in, install the others first, then remove the deck spacer before installing the last screw.
Remember, as you are predrilling and installing screws, the angle of the Camo deck spacer is sharp. Try to mimic this angle in your predrilling along the curve to give the screws the greatest security.
We recommend using two or three people to install each board – one on each side of the deck spacer to screw and one to ensure the board is even and parallel before installation.
Leave the boards to overhang the frame at this point. You’ll cut them all at the very end of your deck floor installation.
Piece by piece, you’ll get your curved deck installed. It looks beautiful when you’re done.
Even if it rains right after installation, you can still appreciate the beauty of a curved redwood deck, right? It’s not easy, and some curves are going to give you fits, but learning how to install curved decking is worth it.