How to Move a Shower Drain in a Concrete Floor

Shifting a shower drain in a concrete floor demands careful planning, specialized tools, and adherence to building standards to maintain structural integrity and prevent water damage. This process transforms outdated bathroom layouts into modern, functional spaces while ensuring long-term reliability.

Why Consider Moving Your Shower Drain?

Repositioning a shower drain becomes necessary during bathroom remodels to accommodate new tile patterns, install larger showers, or integrate linear drains for better aesthetics and flow. Concrete slabs, common in many homes, pose unique challenges due to their solidity, but with proper methods, relocation yields superior drainage exceeding minimum code requirements of 1/4 inch per foot slope.

Benefits include improved water evacuation, reduced slip hazards from standing water, and alignment with contemporary designs like curbless showers. However, improper execution risks cracks, leaks, or plumbing failures, underscoring the need for methodical execution.

Essential Tools and Materials for the Job

Gathering the right equipment ensures efficiency and safety. Key tools include a diamond-blade angle grinder or concrete saw for precise cuts, a jackhammer or chipping hammer for removal, and levels for slope verification. Plumbing requires PVC cutters, primers, and cement for rerouting pipes.

• Cutting tools: 4-1/2 inch diamond blade, wet saw for dust control
• Demolition: Electric jackhammer (15-20 amp), pry bar, shop vacuum
• Plumbing: 2-inch PVC/ABS pipes, elbows, solvent cement matching pipe type
• Leveling: 4-foot level, laser level, mortar mix (e.g., fortified bed mortar)
• Waterproofing: Liquid membrane, bonding flange drains, slurry coat materials

Safety gear such as respirators, goggles, gloves, and knee pads is non-negotiable due to silica dust exposure. Rent heavy tools from home centers to manage costs for one-time projects.

Planning Your Drain Relocation Project

Success hinges on meticulous preparation. Begin by mapping the new drain position, ensuring it aligns with shower walls and allows 1/4 inch per foot slope from all edges. Measure existing pipe depth and calculate excavation needs, typically 4-8 inches for drain body and connections.

Consult local codes via your building department; some areas mandate permits for plumbing alterations. Scan for rebar or utilities using a stud finder with metal detection or professional locator services to avoid hazards.

Sketch the layout, factoring in finished floor thickness (e.g., tile + thinset = 1/2-3/4 inch) to set drain height correctly.

Locating and Marking the Work Area

Identify the existing drain by removing surrounding finishes and tracing the waste line. Use chalk lines to outline the new location, adding 2-3 inches oversize for adjustments. Double-check distances from walls and verify no conflicts with radiant heating or reinforcements.

Mark a grid of shallow score lines with a grinder to guide cuts, preventing slab cracks during demolition.

Precision Cutting and Concrete Removal

Don a respirator and wet-cut the concrete to minimize dust. Make multiple passes: initial 1/4-inch deep perimeter cuts, then deepen gradually to full depth. Switch to a jackhammer for bulk removal, starting from edges and working inward to control debris.

Excavate soil or gravel base if needed, aiming for a stable subfloor. Smooth edges with a grinder and vacuum thoroughly. For linear drains, ensure the trench accommodates the full length while maintaining level.

Pro Tip: Work in sections if relocating far; cut pipe access first to test new routing feasibility.

Rerouting Plumbing Lines Effectively

Cut the existing waste pipe cleanly upstream of bends using a reciprocating saw or PVC cutter. Install new 2-inch pipe with 90-degree elbows, maintaining pitch (1/8-1/4 inch per foot) toward the sewer. Use matching solvent cement: PVC primer/cement for PVC lines, ABS for ABS.

Dry-fit the assembly first, securing with straps every 4 feet. For offsets over 3 feet, incorporate cleanouts for future access. Test connections with water before backfilling to detect leaks early.

Installing the New Drain Assembly

Select a bonding flange drain compatible with your waterproofing system, positioning the flange 1-1/4 inches above the subfloor for mortar bedding. Connect to the waste line securely, then anchor if required for concrete pours.

For linear systems, level along the entire run using shims, ensuring grate sits flush with finished floor. Apply a bead of silicone under the flange for added seal.

Creating Proper Slopes and Mortar Bed

Mix fortified mortar (e.g., 3701 type) and apply a slurry bond coat of latex-modified thinset to the concrete. Pack mortar under the drain flange to the required height, then build slopes from walls: 1/4 inch per foot, screeding smooth with a darby or straightedge.

Overfill slightly and compact in layers to avoid settling. Allow 24-48 hours curb time before waterproofing, verifying slope with a level and water test.

Applying Waterproofing Membranes

Integrate the drain flange with a seamless waterproofing membrane, rolling or troweling per manufacturer specs (e.g., HYDRO BAN systems). Extend up walls 6-12 inches and over slopes, creating flood-testable curbs. Cure fully before tiling to prevent delamination.

For high-moisture areas, add reinforcing fabric at critical joints.

Finishing the Floor and Final Testing

Install backer board on walls, then lay tile with appropriate thinset, using spacers for grout lines. Grout after 24 hours, sealing edges. Flood-test the assembly: plug drain, fill to 2 inches, hold 24 hours, and check for leaks.

Final verification includes flow rate and grate security. Address any issues before full use.

Common Challenges and Pro Solutions

• Uneven Slab: Grind highs or add low-spot mortar; use adjustable drains.
• Rebar Hits: Cut around with reciprocating saw, patch with epoxy.
• Deep Excavation: Backfill with compacted gravel, then concrete for stability.
• Thermal Expansion: Flexible couplings at concrete-pipe interfaces.

Safety Protocols and Best Practices

Prioritize dust control with wet methods and HEPA vacuums; comply with OSHA silica standards. Secure the work zone, especially in occupied homes. Document each phase for permit inspections.

DIY Limit: Simple offsets under 5 feet suit experienced users; longer reroutes or structural concerns require licensed plumbers.

Frequently Asked Questions

Is it feasible to move a shower drain in an existing concrete floor?

Yes, but it involves significant demo and plumbing work, best during full remodels for cost efficiency.

How much slope is required toward the new drain?

Minimum 1/4 inch per foot from farthest point for proper drainage.

What depth should I cut for the drain chase?

Typically 4-8 inches, depending on pipe and drain model.

Can I install a linear drain during relocation?

Absolutely; they excel in concrete with precise leveling and membrane integration.

How long does the full process take?

3-7 days for pros, longer for DIY including cure times.