If you’re building a redwood deck and have installed the deck floor, you’re close to being done.
In this tutorial, we’ll show you a couple of ways to give your deck a finishing touch with trim – around exposed beams, posts, and the edges.
How to Trim Around a Deck Post
If you’re finished with the deck floor, it’s time for trim. If you have any type of post or object protruding through your decking (or along the side of it), consider installing trim around it.
Step 1: Take Your Measurements and Make Cuts
Cut four pieces of wood with 45-degree mitered corners, so the narrowest edges are the same length as the width of the post sides. Use narrow exterior screws (Camo brand screws work well) to attach the first trim piece to the post.
Grab a wide clamp, and clamp the screwed trim piece to the opposite trim piece. Fit the inner piece inside.
Step 2: Screw the Trim In Place
Screw the inner piece into the space, then screw in the third piece as well. Repeat for the fourth trim piece.
Trim adds a nice finishing polish to exterior decks.
How to Trim Around Deck Edges
Here’s how to install trim around your deck edges.
Step 1: Cut Overhanging Boards
If you still have deck boards overhanging your frame, it’s time to cut them into a precise line.
Before you cut, run a chalk line above the outer edge of your frame boards.
Use this chalk line to guide your circular saw down the edge of your deck. You’ll create a flat surface to mount your finishing side piece.
Step 2: Cut Your First Corner Piece
Beginning with the corner piece, use your miter saw to cut a 45-degree angle on the end of a long 2×6 piece of redwood. Ideally, your lumber length will travel the length of your deck side. But that isn’t always the case.
Lay the mitered corner in place against the deck corner. If your deck is longer than your lumber, determine where your side-trim joint will be.
(Note: Dry weather is ideal for any type of decking installation; the weather wasn’t cooperating here. Don’t do this in the rain if you can help it.)
Step 3: Pick a Side Joint Location
In this instance, because there is an existing post on the deck, the best place for a joint is behind it. You want a joint that is unnoticeable, and that has less foot traffic (e.g., behind a post).
With the mitered corner in place, mark on your side trim board where your joint will go.
Use a miter saw to cut the length of your lumber at your marked point.
Fit the corner piece into place, then level the entire length of the board along your deck. Have helpers hold both ends of the board in place -flush against the deck, and level with the top of the deck.
(Tip: If your board isn’t straight, install a screw on one end to hold it in place, then manipulate the lumber, so it’s level and flush. Install a screw on the other end and then fill in the rest of the screws every couple of feet.)
Step 4: Install the Trim with Screws
Keeping the side trim board flush and level (use a 2×4 or pry bar to maintain level, if necessary), predrill through the trim board into the deck floor and the pretreated lumber frame.
Then, using 2-1/2” or 3” exterior deck screws (red finish for redwood), screw the side trim lumber into place.
Install two screws every 2’ or so along the outside of your side trim board, taking care that each screw set installation is onto a flush, level trim board.
Measure the distance between the end of your first board (at the point of your joint) to the other end of your deck, and cut a second side trim piece. Get the two ends flush at your joint, then predrill and install the screws on the second side trim piece.
Step 5: Work Your Way Around the Deck
Work your way around the deck. Predrill before installing the screws, even at the points in the middle of your side trim lumber, for a more accurate install.
Check for level across the side trim board and your deck floor with every screw set installation. Use a helper’s body weight if you need to push the trim piece down a bit, or use a pry bar underneath if you need to raise it an eighth of an inch, but try to get it flush for best deck results.
Move on to install the second piece of your corner side trim with another mitered end.
With the post and side trim pieces in place, you’re ready to finish your deck with stain and sealant.