How to Install Corner Blocks for Baseboard Trim

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Installing baseboard trim is a challenging endeavor that takes years of practice to become proficient. The angled cuts, the slope of the floor and the irregularity of the walls all work against you as you try to get those tight, even corner joints. One remedy for this problem is the use of corner blocks. These blocks add accent to your trim work and allow all of your cuts to be 90 degrees. Corner blocks save time, effort and materials.

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Things You'll Need

  • Saw

  • Wood Putty

  • Caulk Gun With 30-Year Silicone Caulk

  • Baseboard Trim

  • Outside Corner Block

  • Drill With 1/8-Inch Bit

  • Nail Set

  • 8D Finishing Nails

  • Hammer

  • Inside Corner Block

Outside Corner Block Installation

Step 1

Place an outside corner block against the outside corner where two walls meet. Slide the cutout in the back of the block onto the corner and hold it tight to the walls.

Step 2

Drill through the top left side of the block one inch from the top of the block and one inch in from the corner of the walls. Drive a finishing nail through the hole and into the wall with your hammer.

Step 3

Drill a hole through the bottom right side of the corner block. Insert a nail and drive it into the wall.

Step 4

Place the tip of your nail set against each nail head to countersink them below the level of the block. Press wood putty into the holes with your finger and wipe away the excess. Place a bead of caulk around the perimeter of the block to complete the seal.

Installing Inside Corner Blocks and Baseboard

Step 1

Slide the inside corner block into the juncture of two walls on an inside corner. Drill through the block at the top left side and the bottom right side and drive a nail through each hole.

Step 2

Countersink the nails and putty the holes. Caulk the entire perimeter of the block for a complete seal.

Step 3

Lay out your baseboard. Cut it flush to fit flat against the blocks with your saw. Drill the nail holes, secure the baseboard to the walls and countersink the nails with your nail set.

Step 4

Putty the nail holes. Caulk the top, bottom and vertical seams of the baseboard.