What is the best method for checking square when installing a peninsula base cabinet?

• A. Use a laser level
• B. Measure corner to corner and adjust
• C. Check for square with a framing square
• D. Align with a plumb line

Answer: (C)

A framing square is the best tool for this because it directly verifies a true 90-degree angle where the cabinet sides meet the wall, which is what you want to be square on a peninsula base cabinet. You slide the square into the corner or along the adjacent surfaces; if the edges sit flush on both faces, the corner is square. If not, you know you need to adjust or shim to bring it into true square, which is essential for doors and drawers to align and for the peninsula to sit flush with surrounding cabinets.

Laser levels are great for level and plumb lines but don’t give a precise read on a right-angle joint in a tight corner. Measuring corner to corner and relying on diagonals can mislead in field conditions, especially with irregular walls or surfaces. A plumb line checks verticality, not the horizontal square of the joint. The framing square provides a direct, quick check of the required angle.