Converting a bathtub drain to a shower drain is one of the most complex plumbing projects in bathroom renovation. The process requires understanding pipe sizing, proper slope, and code compliance to ensure your new shower drains properly and meets local requirements.
A bathtub to shower drain conversion replaces the existing 1.5-inch tub drain system with a 2-inch shower drain assembly to accommodate higher water flow rates and meet plumbing codes.
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This conversion typically involves cutting the existing drain line, installing a new P-trap assembly, connecting PVC pipes, and ensuring proper slope for drainage. The project can range from $300-800 for DIY materials to $1,800-4,000 for professional installation, depending on complexity and whether concrete cutting is required.
In this comprehensive guide, I'll walk you through the entire process, from understanding code requirements to troubleshooting common issues. After working on numerous bathroom renovations, I've learned that proper planning and attention to detail are crucial for success.
Before starting any drain conversion project, you need to understand the plumbing code requirements. The Uniform Plumbing Code (UPC) provides the foundation for most local regulations, but always check with your local building department as requirements can vary significantly by region.
Shower drains must be 2 inches in diameter according to most plumbing codes, although some jurisdictions allow 1.5-inch drains in specific circumstances. The larger diameter provides better water flow and reduces the risk of clogging with the higher volume of water that showers produce compared to bathtubs.
Proper venting is essential for any drain system to function correctly. Your shower drain needs adequate venting to prevent slow drainage and ensure water flows smoothly without siphoning the P-trap. Most shower drains require a vent pipe within 5 feet of the trap, though this can vary by local code.
P-Trap: A U-shaped pipe that holds water to prevent sewer gases from entering your home. Shower P-traps must be installed with the correct depth and proper venting to function effectively.
Permit requirements vary by location. Many jurisdictions require permits for drain modifications, especially if you're moving the drain location or cutting into concrete floors. Always check with your local building department before starting work to avoid potential code violations and fines.
Inspection requirements typically include rough-in inspection before covering the plumbing and final inspection after completion. The inspector will verify proper pipe sizing, correct slope (typically 1/4 inch per foot for shower drains), adequate venting, and secure connections.
Having the right tools and materials before starting your drain conversion will save time and prevent project delays. Based on my experience with bathroom renovations, here's what you'll need for a typical bathtub to shower drain conversion:
| Item | DIY Cost | Professional Installation |
|---|---|---|
| Basic Materials | $150-300 | $300-600 |
| Conversion Kit | $270-300 | $400-500 |
| Tool Rental (if needed) | $75-150 | Included |
| Permit Fees | $50-150 | $50-150 |
| Total Estimated | $300-800 | $1,800-4,000 |
⏰ Time Saver: Consider renting tools instead of buying if this is a one-time project. Most home improvement stores offer daily rentals at reasonable rates.
When planning your complete bathroom renovation, you might also need new tub surround options if you're removing the existing tub entirely. This can impact your overall budget and timeline.
The following step-by-step process covers a standard bathtub to shower drain conversion. Remember that every project is unique, and you may need to adjust these steps based on your specific situation and local requirements.
Before starting any work, turn off the water supply to the bathroom and open faucets to drain remaining water. Remove any standing water in the tub drain using a wet/dry vacuum. Measure the existing drain location and plan your new shower drain position, keeping in mind that most shower pans require the drain to be centered or positioned according to the manufacturer's specifications.
Take photos of the existing plumbing setup before disconnecting anything. These reference photos can be invaluable if you need to troubleshoot issues later or need professional help. I've learned from experience that documentation saves time and prevents costly mistakes.
Protect the surrounding area with plastic sheeting and drop cloths. Concrete cutting creates significant dust, and demolition work can damage nearby fixtures. Cover floors, walls, and any remaining bathroom fixtures thoroughly.
Begin by removing the bathtub drain assembly. Use channel lock pliers to unscrew the drain flange counterclockwise. If the drain is stuck, apply penetrating oil and let it sit for 15-20 minutes before trying again. In some cases, you may need to use a drain wrench or specialized drain removal tool.
Once the drain flange is removed, you'll have access to the drain pipe below. For tubs on concrete floors, you'll need to cut away concrete around the drain pipe. Use a reciprocating saw with a diamond blade to carefully cut a square section around the pipe, working slowly to avoid damaging surrounding structures.
For tubs on wooden subfloors, use a reciprocating saw to cut away the necessary portion of the subfloor around the drain location. Be careful not to cut through joists or other structural elements. Measure twice before cutting to ensure accuracy.
Once you have access to the drain pipe, measure and mark where you'll need to make cuts. For most conversions, you'll need to cut away a section of the existing 1.5-inch tub drain pipe and connect new 2-inch piping for the shower drain.
Use a pipe cutter or hacksaw to make clean, straight cuts on the existing pipe. Remove any burrs or rough edges with a file or utility knife. The cut surfaces must be smooth to ensure proper sealing with couplings and connections.
Dry fit all your new pipe connections before applying any cement. This allows you to verify measurements and ensure everything fits properly. Make sure you have adequate clearance for the P-trap and that the drain will slope correctly toward the main drain line.
Start by installing the new shower drain flange in the shower pan or on the subfloor. Follow the manufacturer's instructions for proper installation, including any required waterproofing or sealant application. The drain flange must be level and securely attached to prevent leaks.
Install the P-trap assembly below the drain flange. The P-trap should be positioned with the cleanout facing upward and accessible for future maintenance. Use PVC primer and cement to create permanent connections between the P-trap and the drain pipes. Remember that PVC cement sets quickly, so work efficiently and have all pieces ready before applying.
⚠️ Important: Always apply primer before cement when working with PVC pipes. The primer softens the plastic and ensures a proper chemical bond. Skipping this step can lead to leaks and connection failures.
Connect the new 2-inch PVC pipe from the P-trap to the existing drain line. Use no-hub couplings to connect the new PVC to existing metal or different material pipes. These couplings provide a secure, flexible connection that can accommodate minor alignment differences.
Critical to proper drainage is ensuring the correct slope. Shower drains need a minimum slope of 1/4 inch per foot toward the main drain line. Use a level to verify the slope throughout your installation. Adjust as needed before the cement sets permanently.
Support the new piping adequately using pipe hangers or straps every 4 feet along horizontal runs and at every change in direction. Unsupported pipes can sag over time, creating low spots where water can collect and potentially freeze or cause drainage issues.
If working with concrete floors, create a gradual slope using a concrete mix around the drain assembly. This slope helps channel water toward the drain and prevents pooling. Allow adequate curing time before proceeding with the shower pan installation.
Before covering any plumbing or backfilling around pipes, perform a thorough leak test. Fill the P-trap with water and run water through the drain for at least 10-15 minutes. Check all connections for signs of leaking. Use dry paper towels around each joint to detect even small leaks.
Request a rough-in inspection from your local building department if required. The inspector will verify that your installation meets code requirements regarding pipe sizing, slope, venting, and connection methods. Address any issues before covering the plumbing.
Once inspections are complete and everything passes, you can proceed with backfilling around the pipes and installing your shower pan. If using a pre-fabricated shower pan, follow the manufacturer's installation instructions carefully, including any required waterproofing or sealing procedures.
Even with careful planning and execution, issues can arise during drain conversion projects. Based on my experience and insights from professional plumbers, here are the most common problems and their solutions:
If water pools around the drain or drains slowly, the slope is likely insufficient. The minimum requirement is 1/4 inch per foot, but slightly more slope can improve drainage. Use a level to check the slope and adjust supports as needed. In severe cases, you may need to redo the installation with proper sloping.
Leaks at pipe connections are common and usually result from improper cleaning before cement application, insufficient primer, or misaligned pipes. Turn off the water, allow the area to dry completely, and clean all surfaces with PVC cleaner. Re-apply primer and cement to create a proper seal.
Symptoms of poor venting include gurgling sounds, slow drainage, or P-trap siphoning. Most shower drains require venting within 5 feet of the trap. If your existing vent is too far away, you may need to install an air admittance valve or extend the vent line. Consult local code requirements for specific venting rules.
✅ Pro Tip: When troubleshooting drainage issues, start with the simplest solutions first. Often, clearing blockages or adjusting slope can resolve problems without major rework.
Cutting through concrete floors can be difficult and time-consuming. If you're struggling with a reciprocating saw, consider renting a concrete saw with a diamond blade for faster cutting. Always wear appropriate safety equipment including eye protection, gloves, and a dust mask when cutting concrete.
While DIY drain conversion is possible for experienced homeowners, certain situations warrant professional help. If you encounter any of these issues, it's time to call a licensed plumber:
A DIY bathtub to shower conversion typically costs $300-800 for materials and tool rentals. Professional installation ranges from $1,800-4,000 depending on complexity, location, and whether concrete cutting is required. Permit fees add $50-150 to either approach.
Yes, most tub-to-shower conversions require drain relocation because tub drains are typically 1.5 inches while showers require 2-inch drains. Additionally, the drain position may need to shift to accommodate the shower pan's specifications and proper slope toward the main drain line.
While some local codes allow 1.5-inch drains for showers in specific circumstances, most jurisdictions and professionals recommend 2-inch drains for showers. The larger diameter provides better water flow, reduces clogging risk, and accommodates the higher volume of water that showers produce compared to bathtubs.
Moving a shower drain in concrete requires cutting away the concrete around the existing pipe, relocating the drain line, and then backfilling with concrete. Use a reciprocating saw with diamond blade or concrete saw, wear proper safety equipment, and ensure proper slope and support before pouring new concrete.
Permit requirements vary by location but most jurisdictions require permits for drain modifications, especially if you're moving the drain location or cutting into concrete floors. Always check with your local building department before starting work to avoid potential code violations and ensure proper inspections.
Shower drains require 2-inch diameter pipes according to most plumbing codes. This provides adequate water flow for the higher volume showers produce compared to bathtubs. The drain line should maintain consistent 2-inch diameter from the shower drain to the main vent stack or connection point.
A bathtub to shower drain conversion is a complex project that requires careful planning, technical knowledge, and attention to detail. While DIY installation can save money, don't underestimate the complexity, especially if concrete cutting or significant pipe relocation is involved.
For those considering complete bathroom renovations, a drain conversion is often just one component of a larger project. You might also want to explore bathroom vanity options or modern toilet options to complete your bathroom transformation.
If you're uncertain about any aspect of the conversion, especially regarding code compliance or complex pipe routing, don't hesitate to consult a licensed plumber. The cost of professional help is often less than the expense of fixing mistakes or addressing code violations later.
Remember that proper drainage is essential for a functional, long-lasting shower. Take the time to ensure every connection is secure, every slope is correct, and every code requirement is met. The extra attention to detail will pay off in years of reliable performance from your converted shower drain.