Tub-to-Shower Conversion: A Plumbing Guide
Converting an old bathtub into a modern walk-in shower requires upgrading drain line size from 1.5 inches to 2 inches. Read our expert tips.
Why Tub-to-Shower Conversions Are Popular in Sarasota
Many Sarasota homeowners are converting unused bathtubs into modern walk-in showers. Whether you are updating a master bath, improving accessibility, or simply prefer showers to baths, a tub-to-shower conversion is one of the most impactful bathroom upgrades you can make.
But it is not as simple as removing the tub and dropping in a shower pan. The plumbing underneath needs to be modified—and if it is not done correctly, you will end up with water pooling, slow drainage, and potential water damage.
The Drain Size Difference: 1.5 Inches vs. 2 Inches
This is the most important plumbing detail in a tub-to-shower conversion. Standard bathtub drains are 1.5 inches in diameter. Walk-in showers require a 2-inch drain line.
Why? A shower can deliver water at a higher flow rate than a tub spout—especially if you have multiple showerheads or body jets. A 1.5-inch drain cannot keep up with that flow rate, and water will pool around your feet. Upgrading to a 2-inch drain ensures the water drains as fast as it comes out of the showerhead.
This means we need to cut into the floor to replace the drain line from the shower pan to where it ties into the main waste line. It is the most labor-intensive part of the conversion, but skipping it is the most common mistake we see in DIY conversions.
Other Plumbing Considerations
Shower valve replacement: Most tub-to-shower conversions replace the old tub spout and diverter valve with a dedicated shower mixing valve. We recommend pressure-balance valves that prevent scalding when someone flushes a toilet or turns on a cold faucet elsewhere in the house.
Supply line relocation: If your new shower layout is different from the old tub layout, we need to relocate the hot and cold supply lines inside the wall before the tile goes on.
Waterproofing: The shower pan liner and waterproofing membrane are critical. A small leak behind the wall can cause extensive drywall and subfloor damage. We pressure-test all lines before walls are closed up.
Coordinating With Your Remodeling Team
If you are working with a general contractor, tile setter, or designer, we coordinate the plumbing rough-in and finish phases to fit their schedule. Rough-in happens before the tile goes on; finish trim (installing showerheads, handles, and valves) happens after the tile is complete.
Communication between the plumber and the rest of the remodeling team is essential to keeping the project on schedule. At Johnson & Sons Plumbing, we pride ourselves on clear communication and smooth coordination with your remodeling team.
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