Thinking about swapping your bathtub for a sleek, modern shower? You’re not alone—over 60% of U.S. homeowners prioritize walk-in showers during bathroom renovations (National Association of Home Builders, 2023). But before you rip out that tub, you might be asking: “Are there plumbing requirements to change from tub to shower?” The short answer: yes, and understanding them upfront can save you time, money, and headaches. In this guide, we’ll walk you through everything you need to know—from code compliance to drain repositioning—so your conversion goes off without a drip.
Do You Need a Permit to Convert a Tub to a Shower?
Yes, most municipalities require a plumbing or bathroom renovation permit when converting a tub to a shower. Why? Because this change often involves altering water lines, drains, and possibly the structural layout—all of which are regulated under local building codes.
According to the International Residential Code (IRC), any modification to plumbing fixtures must comply with safety and sanitation standards. Skipping a permit might seem like a shortcut, but it can:
Void your home insurance
Cause issues during home resale
Lead to fines if discovered during inspection
Pro Tip: Always check with your local building department first. Permit fees typically range from $50 to $300, a small price compared to potential legal complications.
What Plumbing Changes Are Typically Required?
Converting a tub to a shower isn’t just cosmetic—it often demands real plumbing work. Here’s what usually needs attention:
1. Drain Repositioning
Tubs use a 1.5-inch drain, while showers require a 2-inch drain to handle faster water flow and prevent flooding. If your existing drain is too narrow or in the wrong spot (e.g., tub drains are often centered, while shower drains are offset), you’ll need to reroute it.
2. Water Supply Lines
Tubs have separate hot/cold handles or a mixer valve located lower on the wall. Showers need a shower valve positioned 48–60 inches above the floor, plus a showerhead arm (typically at 72–80 inches). Existing lines may need extension or rerouting.
3. Waterproofing & Slope
While not “plumbing” per se, proper floor slope (¼ inch per foot toward the drain) and waterproof membrane installation are critical. Without them, water seeps into subfloors—leading to mold, rot, and structural damage.
💡 Expert Insight: “I’ve seen 30% of DIY tub-to-shower conversions fail within a year due to poor drainage or inadequate slope,” says Marcus Lee, a licensed master plumber in Austin, TX, with 18 years of experience.
How Much Does Plumbing Work Cost for a Tub-to-Shower Conversion?
Costs vary widely based on complexity, but here’s a general breakdown (2025 data from HomeAdvisor and Angi):
Component
Average Cost Range
Permit fees
$50 – $300
Drain line modification
$200 – $600
New shower valve & piping
$300 – $800
Waterproofing & slope correction
$400 – $1,200
Total plumbing-only cost
$950 – $2,900
⚠️ Note: These costs exclude tile, fixtures, or labor for demolition/installation—just the plumbing essentials.
If your existing plumbing lines align well with shower standards (e.g., valve height is already correct), you might only need minor adjustments. But in older homes (pre-1980s), outdated galvanized pipes or improper venting can escalate costs quickly.
Code Compliance: What the IRC and Local Codes Say
The International Plumbing Code (IPC) and International Residential Code (IRC) set baseline standards, but local jurisdictions can be stricter. Key requirements include:
Shower size: Minimum 30” x 30” (IRC R307.1)
Drain size: 2-inch minimum (IPC 409.2)
Water heater capacity: Must support continuous flow (showers use ~2.5 GPM vs. tubs’ 4–6 GPM in bursts)
Ventilation: Bathrooms must have mechanical exhaust (IRC M1507) to control humidity
While a handy homeowner might tackle tile or fixtures, plumbing work involving drain repositioning or pipe rerouting should be left to licensed professionals. Why?
Leak risk: A poorly soldered joint or misaligned P-trap can cause hidden water damage.
Code violations: DIYers often overlook slope, venting, or trap seal depth requirements.
Warranty issues: Many shower pans and systems void warranties if not installed by certified contractors.
That said, if your setup is simple (e.g., keeping the same footprint, no drain move), you might only need a plumber for final connections—saving 30–50% on labor.
Step-by-Step: How a Professional Handles the Conversion
Here’s how a licensed plumber typically executes the plumbing portion:
Shut off water supply and drain existing lines.
Remove tub and inspect subfloor for damage or rot.
Cap or reroute old tub spout lines if no longer needed.
Install new 2-inch PVC drain line with proper slope (¼” per foot).
Mount shower rough-in valve at 52” height (standard for accessibility).
Connect hot/cold supply lines using PEX or copper (local code dependent).
Pressure-test all lines for 15 minutes at 80 PSI—zero drop allowed.
Coordinate with tile contractor to ensure waterproof membrane (e.g., Schluter-Kerdi) wraps over drain flange correctly.
✅ Best Practice: Always do a 24-hour flood test on the shower pan before tiling—fill with 2 inches of water and check for leaks below.
Tub-to-Shower Conversion: Pros and Cons
Pros
Cons
✅ Saves water (avg. 15–20 gallons per use vs. tub’s 35–50)
❌ May reduce home value in family-heavy markets
✅ Improves accessibility (ideal for aging in place)
❌ Plumbing changes can be costly in slab foundations
✅ Modernizes bathroom aesthetics
❌ Not ideal if you have young kids who need baths
FAQ Section
Q1: Can I keep the same drain when switching from tub to shower?
A: Only if it’s already a 2-inch drain and correctly positioned. Most tubs use 1.5-inch drains, which are too small for showers and violate code.
Q2: Do I need to move the water heater?
A: Not usually. But if your current heater is undersized (<40 gallons for a household of 2+), you may notice reduced hot water during long showers.
Q3: Is a curbless (zero-threshold) shower allowed by code?
A: Yes—and even encouraged for accessibility—but it requires precise slope (¼” per foot) and often a linear drain. Local codes may require a small ½” lip in some areas.
Q4: How long does the plumbing portion take?
A: Typically 1–2 days, assuming no hidden issues like corroded pipes or slab leaks.
Q5: Will this conversion affect my home’s resale value?
A: It depends. In markets with older buyers or empty nesters, a walk-in shower boosts appeal. But in family neighborhoods, removing the only tub may deter buyers—70% of parents prefer at least one bathtub (NAHB, 2024).
Q6: Can I convert a tub to a shower in a mobile home?
A: Yes, but plumbing is more compact. Always verify with your manufacturer’s guidelines—some modular systems restrict drain modifications.
Conclusion
So, are there plumbing requirements to change from tub to shower? Absolutely—and addressing them properly is the key to a safe, code-compliant, and long-lasting upgrade. From drain size to valve height and waterproofing, every detail matters. While it’s tempting to cut corners, investing in professional plumbing work protects your home, your health, and your investment.
If this guide helped you understand what’s really involved in a tub-to-shower conversion, share it with a friend planning a bathroom remodel! And don’t forget to check your local building codes before you start—your future self (and your wallet) will thank you.
💧 Ready to upgrade? Get 3 free quotes from licensed plumbers in your area today!
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