Tub-to-shower conversion: plumbing scope that changes the budget

The budget turns on the drain, valve, and waterproofing plan. A shower is not simply a tub with a different pan. KOHLER describes tub-to-shower conversion as a professional installation process, while ASSE’s product standards cover automatic compensating valves used in showers and tub/shower combinations. Ask for the selected valve, shower base, drain position, and waterproofing system before accepting a total. KOHLER tub-to-shower conversion and ASSE product standards

Scope that belongs in every bid

Work area	Questions for the contractor
Drain	Does the new base align with the existing trap and drain, or will piping move?
Valve	Is the valve reused, serviced, or replaced; can it meet shower temperature-control requirements?
Supply	Are hot and cold lines correctly located for the new valve and trim?
Waterproofing	What membrane, pan, curb, niches, and flood-test method are included?
Finishes	Who supplies wall panels or tile, glass, trim, grab bars, and paint?

ASSE identifies automatic compensating valves as a defined shower product category. A quote that says “new shower valve” should name the model and control type so temperature safety and trim compatibility can be reviewed.

The plumbing decisions to price first

A centered tub drain may not match the shower base. Moving it can require access below or through the floor and may expose a deteriorated trap. The valve may sit too low, be the wrong type, or lack access for service. Ask whether the contractor will open the wall, how the old tub supply is capped, and how the new shower arm and controls will be tested before finishes close.

Waterproofing and plumbing are linked but separate. Request the membrane and pan details, seams and penetrations, drain flange, and test procedure. A shower can have a watertight valve connection and still fail at the pan or wall system. Glass and finish work should not be used to conceal an undefined waterproofing allowance.

Compare complete conversion proposals

Separate demolition, plumbing, waterproofing, wall finish, glass, electrical, permits, and restoration. Ask for an alternate that reuses the existing drain or valve only if the contractor documents compatibility. Request a drawing with dimensions, control locations, drain center, curb or curbless transition, and access panel.

For broader bathroom scope, see bathroom remodel cost. National conversion prices omit the exact base, wall system, access and finish decisions; obtain a room-specific proposal and confirm the local permit path.

Before demolition, require a dimensioned plan and a written finish schedule. Confirm the shower threshold, control reach, niche locations, grab-bar blocking, drain cover, and service access. During the work, photograph the rough plumbing and waterproofing before tile or panels cover it. At handoff, request the valve model, care instructions, warranty, and any test record. Those deliverables protect the plumbing decision after the bathroom looks finished.