(Updated December 9, 2025) As an investor, I view old plumbing not as a repair item, but as a ticking financial time bomb. The single most common—and expensive—emergency is a catastrophic water leak caused by failing Polybutylene or brittle original PEX.
Replacing the entire plumbing system with modern PEX is the ultimate insurance policy against subfloor rot and tenant calls. While the professional cost is substantial (often $2,500 to $6,000), it’s a non-negotiable expense for a permanent flip or long-term rental. This guide breaks down the true cost of PEX repiping, the difference between PEX types, and the exact moment when you must replace the entire system.
Affiliate Disclosure: This guide contains affiliate links to plumbing equipment, PEX tubing, and specialized tools required for a whole-house repipe. If you purchase through these links, Mobile Home Friend may earn a small commission, at no extra cost to you.
Table of Contents
The Short Answer: Whole-House Repiping Costs (2025 Estimates)
The cost to repipe a mobile home is almost entirely dependent on the home’s size and whether you hire a professional plumber or choose the DIY route (which is feasible with PEX).
| Scope of Work | Average Installed Cost Range (Pro) | DIY Material Cost Only |
|---|---|---|
| Full Repipe (Single-Wide, 1 Bath) | $2,500 – $4,000 | $500 – $800 |
| Full Repipe (Double-Wide, 2 Bath) | $4,000 – $6,500 | $800 – $1,200 |
| Repair (Localized Burst) | $300 – $800 | $20 – $50 |
Investor Rule: If the current plumbing is Polybutylene or the home is over 25 years old, a full repipe is mandatory, regardless of the immediate cost. The failure risk is too high.
Why Repiping is a Non-Negotiable Investment
Unlike cosmetic upgrades, repiping is a foundational upgrade that removes catastrophic risk and adds substantial value to your property’s inspection report.
1. Eliminating Polybutylene (The Lawsuit Pipe)
If your home uses gray or black Polybutylene (PB) pipe, you are sitting on a class-action lawsuit time bomb. PB plastic degrades when exposed to common water chemicals like chlorine, becoming brittle and prone to sudden, widespread failure. Lenders and insurance companies often require replacement of PB before underwriting.
2. Avoiding Subfloor Catastrophe
The majority of subfloor damage and rot in mobile homes (as discussed in my subfloor guide) is caused by slow, hidden plumbing leaks. PEX, with its flexible nature and minimal joints, eliminates the joints where leaks typically start. This protects your expensive flooring and subfloor investment.
If you discover existing water damage during the repipe, you must immediately address it. See the full guide: The Complete Guide to Mobile Home Subfloor Repair.
3. Flexible, Freeze-Resistant Plumbing
PEX pipe is highly flexible. Unlike rigid copper or CPVC, it can expand significantly when water freezes, drastically reducing the risk of a burst pipe in cold weather. This is an essential feature for mobile homes where pipes run through the exposed underbelly.
PEX-A vs. PEX-B: Choosing the Right Pipe
PEX (Cross-linked Polyethylene) comes in three main types (A, B, and C), but for mobile home repiping, you will primarily use PEX-A or PEX-B. The difference is the cost of the material versus the cost of the required tools.
- PEX-A (Expansion/Wirsbo Method): This is the superior material. It uses a tool to expand the pipe before a fitting springs back into place, creating the strongest connection. PEX-A is more flexible and holds its shape memory better. The drawback is the high cost of the expansion tool ($300+).
- PEX-B (Crimp/Cinch Method): This is the most common DIY and contractor choice. It uses a metal ring (either copper crimp or stainless steel cinch) that is compressed onto the pipe. The material is slightly stiffer, but the tools are far cheaper and easier to use ($50-$100). PEX-B is perfectly acceptable for mobile home applications.
Recommendation: For DIY repiping, PEX-B and the cinch tool offer the best combination of quality and low tool cost. For a professional job, insist on PEX-A for maximum durability.
DIY Repiping: How to Save Thousands in Labor
Repiping a mobile home with PEX is one of the most feasible high-value DIY projects. The pipe runs almost entirely under the home, making access straightforward compared to site-built homes where pipes run through walls and ceilings.
Three Critical Steps:
- Access the Underbelly: You must have safe, clear access under the home. If your belly wrap is damaged, you will need to replace it. A sealed underbelly is also critical for insulating the new pipes: The True Cost of Mobile Home Underbelly Insulation.
- Run the Homing Runs: PEX is flexible enough to run one continuous hot and cold line to each fixture (sink, toilet, shower) with minimal fittings. This is the biggest PEX advantage.
- Use Proper Supports: Do not let the PEX line rest on the ground. Use plastic pipe hangers every few feet to secure the line to the floor joists. This prevents abrasion and protects the lines from pests.
🛠️ Key Product Recommendations for DIY Repiping
If you choose to perform the repipe yourself, these are the two essential components that will determine the quality and cost-effectiveness of the job. Focus on the PEX-B system for the best balance of price and performance.
✅ Option 1: The Essential PEX-B Crimp Tool Kit
The PEX-B Crimp Tool is the heart of the DIY repipe. This PEX-B Crimp Tool Kit provides everything needed to make secure, leak-proof connections using the cinch method. Investing in a high-quality tool ensures your joints will pass inspection and prevent future water damage.
✅ Option 2: Whole-House PEX-B Tubing and Fittings Bundle
Running continuous lines of PEX saves on fittings, but you still need a bulk supply of the correct material. This Whole-House PEX-B Tubing Bundle provides enough red and blue tubing, along with necessary fittings, to complete a double-wide repiping, avoiding multiple trips to the hardware store.
Summary
Repiping your mobile home with PEX is a proactive, defensive investment. It removes liability, eliminates future water damage, and adds instant value and confidence for buyers and renters. Never attempt to patch Polybutylene; full replacement is the only solution. PEX-B is the best balance of DIY feasibility and high performance.
Related Questions
- Can I connect PEX to the old Polybutylene pipe? Yes, you can use specialized transition couplings that connect PEX to Polybutylene. However, this is only acceptable for localized repairs, not a full repipe. If you are repiping the house, the transition should be made at the main water supply and not continue the Polybutylene through the house.
- Do I need to insulate the new PEX pipes? Absolutely. Even PEX can freeze and burst if exposed to extreme cold. Use foam pipe insulation on all runs, particularly where the lines drop down from the floor to the faucet connections.
Written by a real estate investor who has successfully renovated over 100 properties, specializing in risk elimination via foundational upgrades like whole-house PEX repiping.