How to Cut a Bathroom Subfloor

Lay cut lines on the subfloor at the location where you'll make a hole by placing pencil marks and snapping straight lines with a chalk box. Check the resulting chalk lines to see whether or not fasteners are in the cutting path. Pull out fasteners with a nail claw and hammer.

Put on safety glasses and a dust mask. Place one earplug in each ear.

Release the lever that locks a circular saw's cutting table into place. Slide the cutting table down while observing the etched measurements on the curved arm by the lever. Stop sliding the table down once the 3/4-inch etched mark lands on the arrow. Lower the lever to lock the table at that etched mark.

Rest the front lip of the circular saw's table on the subfloor. Align the cutting blade with the beginning of the snapped chalk line. Squeeze the saw's power trigger or button, and allow the blade to circulate at the full revolutions per minute (rpm).

Swing the saw down gently, allowing its rotating blade to cut into the subfloor material. Push the circular saw in a forward direction along the snapped chalk line when the cutting table is flush against the subfloor.

Stop pushing the saw forward when you reach the opposite end of the snapped chalk line. Release the saw's power trigger or button, and wait until the blade stops completely; then remove the blade from the subfloor material.

Move to the next snapped chalk line, and repeat the cutting process.