Step 2 · Subfloor and Framing Preparation
With the alcove empty, thoroughly clean all debris from the subfloor and studs. Inspect the subfloor for any signs of water damage, rot, or weakness. Repair or replace any damaged sections of plywood or OSB. Use a 4-foot level to check that the subfloor is perfectly level where the tub will sit. If it is not, use a self-leveling compound to create a flat, level surface. Inspect the wall studs for plumb and ensure they are sound. If required by the tub manufacturer, install a ledger board. This is typically a straight 2x4 screwed horizontally to the studs along the back wall. Measure up from the subfloor to the height specified in the tub's installation manual (this height corresponds to the underside of the tub's rim). Use a level to ensure the ledger board is perfectly level before securing it to the studs with long wood screws.