How to Trim a Redwood Deck

Trimming a Redwood Deck

When building a redwood deck and finishing the deck floor, there are a few ways to add trim for a polished look. This tutorial will guide you through the process of trimming around exposed beams, posts, and edges to complete your deck.

Trimming Around a Deck Post

Once you’ve completed the deck floor, it’s time to focus on the trim. Install trim around any posts or objects that protrude through or along the side of your decking.

Step 1: Measure and Cut

With 45-degree mitered corners, cut four pieces of wood to match the width of the post sides. Attach the first trim piece to the post using narrow exterior screws, such as Camo brand screws.

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 and screw in the third piece. Repeat for the fourth trim piece.

Trim adds a finishing polish to exterior decks.

Trimming Deck Edges: A Step-by-Step Guide

Learn how to install trim around your deck edges with these easy steps.

Step 1: Cut Overhanging Boards

If your deck boards still hang over the frame, it’s important to cut them into a precise line.

Before cutting, 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 redwood piece. Ideally, your lumber length will travel the length of your deck side. But that isn’t always the case.

Place the mitered corner against the deck corner. If your deck is longer than your lumber, decide where your side-trim joint will be. (Note: Dry weather is best for decking installation; avoid doing it in the rain if possible.)

Step 3: Choose a Joint Location

In this case, the best location for a joint is behind the existing post on the deck. The goal is to have a joint that is unnoticeable and experiences less foot traffic.

Once the mitered corner is in place, mark the spot on your side trim board where the joint will be placed.

Use a miter saw to cut your lumber at the marked point.

Fit the corner piece into place, then level the board along your deck. Have helpers hold both ends of the board flush against the deck and level with the top. If the board isn’t straight, install a screw on one end to hold it in place, then manipulate the lumber to make it level and flush.

Install a screw on the other end and fill in the rest of the screws every couple of feet.

Install the trim with screws by predrilling through the side trim board into the deck floor and the pretreated lumber frame. Keep the trim board flush and level, using a 2×4 or pry bar if needed.

Using 2-1/2” or 3” exterior deck screws (red finish for redwood), screw the side trim lumber into place.

Install screws every 2’ along the outside of the side trim board, ensuring that each screw is set flush and level with the trim board.

To measure the distance between the end of your first board and the other end of your deck, cut a second side trim piece. Make sure the ends are flush at the joint, then predrill and install the screws on the second side trim piece.

Work your way around the deck. Pre-drill before installing the screws, even in the middle of your side trim lumber, for a more accurate install.

Check the levelness of the side trim board and deck floor with each screw installation. If necessary, use a helper’s body weight to push the trim piece down or a pry bar to raise it slightly, aiming to achieve a flush position for optimal deck performance.

Install the second piece of your corner side trim with another mitered end.

You can finish your deck by applying stain and sealant once you have installed the post and side trim pieces.