Step 1: Measure and Cut the Wood

Measure the mirror on the wall to determine the length and width of frame (Image 1).

Using a table saw, cut the trim and molding pieces to size. Keep the table saw unplugged when not in use, especially when adjusting the blade or fence.

Now cut out a pocket or groove in the primary trim pieces to accommodate the edges of the mirror (Image 2).

Note: Figure your preferred finish for the frame first. It's easier to apply stain to the wood pieces prior to installation. Painting can be done after installation.

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    Image 1

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    Image 2

Step 2: Nail the Wood to the Wall

Nail the sides of the frame to secure the trim pieces to the wall with grooves facing down over the mirror.

Continue with nailing the top and bottom of the frame, taking care to avoid hitting the mirror.

Step 3: Trim the Wood Frame

Add a sill board on the bottom edge of the frame (Image 1).

Cover any visible screw holes with a thin trim piece, such as 3/16" in depth, to make a false front and nail it into place using small nails.

Next, add the final molding trim pieces around the top and sides of the frame (Image 2).

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    Image 1

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    Image 2

Step 4: Finish the Wood Frame

Cover the nail holes with wood putty.

Add a bead of silicone around the mirror for added stability, wiping up any excess on the wall with a clean wet rag.

Paint or finish as desired.