A PEX repipe goes in this order: shut off and drain the water, plan the layout, open access, run the new pipe, connect fixtures and the water heater, pressure test, pass inspection, patch the walls. Each step is plain enough to describe, and a few are risky enough that most homeowners hire it out. For the overall job, costs and permits, see the main guide to repiping a house in Los Angeles.
What are the steps to repipe a house with PEX?
The work runs in eight steps: plan the layout and get a permit, shut off the main and drain the system, open access holes, run PEX to each fixture, connect to the water heater and the main, pressure test, pass the LADBS inspection, then patch walls. The plumbing alone commonly takes one to three days for a typical house.
- Plan. Walk every fixture and decide the route. A manifold layout runs a line from a central hub to each fixture. A trunk-and-branch layout is closer to the old system and uses fewer feet of pipe.
- Permit. Apply for the LADBS plumbing permit before work starts.
- Shut off. Close the main, open the lowest and highest taps to drain the system and shut off the heater.
- Access. Cut small openings where lines drop to fixtures. Work through the attic or crawl space where you can.
- Run the pipe. Pull PEX through, support it at the spacing the manufacturer says and leave room for expansion.
- Connect. Join to each fixture shutoff, the heater and the main.
- Test and inspect. Pressurize the system, hold it, and call for the rough inspection with the pipes still exposed.
- Patch. Close the walls only after the inspector signs off.
Do you need a permit to repipe a house with PEX in Los Angeles?
Yes. Replacing the water supply lines in a Los Angeles house needs a plumbing permit from LADBS, and the inspector looks at the work before walls are closed. California has approved PEX for house plumbing under the state plumbing code since 2009, with a legal back and forth in 2010, so the material itself is allowed.
The permit is not optional paperwork. It gives you an inspection of the pressure test and the installation, and it gives you a record for the insurer and for a buyer. Published contractor guides say a plumbing contractor normally pulls it. Expect a rough inspection and a final one. Ask LADBS what an owner-builder must provide if you pull your own, and what happens if the inspector fails the work.
LADBS's own pages are the authority, and some of its details change, so check them before you start rather than relying on any blog, including this one.
Can I repipe my own house with PEX?
Legally, a California homeowner can sometimes act as their own contractor on their own house, with a permit and inspections, under the owner-builder rules. Practically, a whole-house repipe is a large, wet job with a water-damage downside, and many homeowners are better off hiring it out. Gas piping and the main service line need a plumbing contractor.
If you hire anyone to do plumbing, California requires a licensed contractor for permit work, and you should check the license at cslb.ca.gov. A homeowner can reasonably do a small thing: replace a fixture shutoff or a supply line to a toilet. Opening walls, rerouting and connecting to the main is where mistakes become floods. Water damage is also the thing homeowner policies like to argue about.
If you decide to do part of it, decide what you will not do: the main connection, the water heater hookup and anything gas related belong to a plumber.
What tools and fittings does a PEX repipe need?
The kit depends on the type. PEX-B uses crimp or cinch ring tools and a go/no-go gauge. PEX-A uses an expansion tool and expansion rings. Both need a tubing cutter, a manifold or tees, shutoffs and supports. Tool costs run from about $30 to $150 for crimp tools and from about $100 to several hundred dollars for expansion tools.
Match fittings to pipe. Expansion fittings are made for PEX-A, and crimp or clamp rings can be used on either type. Do not mix brands without checking the manufacturer's listing. The choice is explained on the page about PEX A versus PEX B. The tool cost often rivals the labor you were hoping to save on a one-time job.
What mistakes cause PEX leaks?
Most leaks come from a bad fitting, a kink, a bad crimp, pipe left in sunlight or a connection to old pipe done without the right transition. A crimp that is not checked with a gauge is the classic one. Mismatched metals at a connection to old galvanized steel cause corrosion at that joint.
Other mistakes: bending tighter than the minimum radius, no room for thermal expansion, long unsupported runs that rattle and tap and let water hammer travel (see water hammer sounds), and not protecting pipe where it passes through framing. Keep PEX out of sunlight, since UV weakens it, and away from recessed lights and the heater flue. Pressure testing before closing the walls catches most of this.
Should I repipe my house with PEX?
If your house has galvanized steel, polybutylene or copper that keeps leaking, PEX is a reasonable and common choice, and it is usually cheaper than copper. If the system is sound, you may not need a repipe. The reasons to act are in why repipe a house, and a comparison with copper is in PEX versus copper.
One more thing to check is the water pressure. Los Angeles has areas with high static pressure, and a regulator is required over 80 psi, per the plumbing code. A new system without a regulator will see that pressure at every joint. The page on the water pressure regulator explains the part.
Common questions
How much does it cost to repipe a house with PEX?
Published guides put a PEX repipe at about $4,000 to $10,000 for a 2,000 square foot, two-bath house, with a national average near $6,500. Los Angeles access, a slab foundation or a second story can raise it. A written quote after a visit is the real number, and PEX repipe cost has the detail.
How long does it take to repipe a house with PEX?
The plumbing itself commonly takes one to three days for a typical house, per published timelines, and the full project including the rough inspection and wall patching often takes a week or two. Water is usually off for part of each working day, so plan for it.
Can you repipe a house with PEX without opening the walls?
Not entirely. A few access holes are almost always needed, usually at fixture drops and shutoffs, though much of the run can go through an attic or crawl space. PEX needs fewer openings than copper because it bends. Ask who patches and paints the openings.
Is PEX allowed in California?
Yes. The California Building Standards Commission approved PEX for the state plumbing code in 2009, with a court-ordered repeal in 2010 and a later re-approval after more environmental review. Many cities had approved it locally before that. Los Angeles permits it, but confirm current rules with LADBS.
What do you do with the old pipes after a PEX repipe?
Plumbers usually cap and abandon old pipes in the walls instead of removing them, because that saves tearing out plaster and drywall. They must be disconnected from the water supply and capped. Old cast iron drains are a separate system and stay unless they are also failing.
Prefer to have it done? The quote page lets you ask for a written quote and a local plumber comes to you.