How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
How much does it cost to replace the plumbing pipe in a house?
Thursday, September 13, 2018
“The price can vary a lot according to the size and type of construction of a particular house, but the average price for repiping is around $6000,” according to James Freeman, of J.W. Freeman Plumbing, in Gainesville, Florida. That’s for repiping a typical 3-bedroom, 2-bath home, including the pipe from the meter to the house. There are three different types of pipe material that may require replacement:
1) Copper pipe can fail due to corrosive water or soil, defective pipe material, or poor installation. Defective pipe can begin to fail as early as 6 to 8 years after installation. When it begins to leak, the first place is typically under the floor slab. “But a single leak is not a reason to replace the whole system,” according to James. “One leak just needs to be repaired. More than one leak and its time to replace the piping.”
2) Galvanized steel pipe, like in the photo at the top of the page, has an average lifespan of 40 to 50 years, although it can sometimes last much longer. Flakes of corroded steel peel off the interior surface of the pipe and get carried to the back side of faucets in the home, where they gradually accumulate and restrict the water flow. Many homeowners with older galvanized steel pipe complain of low water pressure, but the water pressure is not the problem. It’s severely restricted flow—a kind of arteriosclerosis of the pipe. The corrosion eventually eats through the pipe walls and the system starts springing leaks. Galvanic corrosion, which is an electrolytic reaction between two different metals, can speed up the corrosion and cause earlier leakage at the water heater if there are short sections of copper pipe used to connect the water heater.
3) Polybutylene, called “PB” in the trades, was installed in homes from the late 1970s to the early 1990s, when it was banned after numerous early failures of the piping. It was especially popular with mobile home manufacturers, and is usually gray, with copper-color crimp fittings at pipe connections. Class action lawsuits awarded money for replacement to homeowners with PB, but the period for initiating a claim has ended. Most of the early failures were due to sloppy crimping of the pipe connections.
“If it hasn’t started leaking by now, it’s probably fine” is our plumber friend James Freeman’s opinion. “I think it is an inferior pipe material, but would not replace it at this point unless it started leaking.” Unfortunately, many insurance companies do not agree, and will not issue a new homeowner’s policy on a house with PB piping. So replacement may be necessary for securing insurance.
Most water supply piping is simply abandoned in place when replaced. There are three different installation strategies that a plumber can use for replacement of your water supply piping, depending on the construction type of your home:
- Through the attic is preferable for a slab-on-grade home with adequate attic height for the plumber to maneuver around. The pipe is run down the interior walls from the attic to each fixture’s shut-off valve location. The exposed pipe in the attic must be insulated (to protect against pipe fractures due to freezing) and adequately secured.
- Under the floor is best for older homes with a wood floor over a crawl space, and is also the easiest and least expensive pipe replacement method. Again, like in an attic installation, the exposed pipe in the crawl space must be insulated and secured.
- In the ground, running around the outside walls is the only choice for slab-on-grade homes with a flat or low-slope roof with not enough attic space. The pipes will come up out of the ground at each exterior wall location near a bathroom, kitchen, or laundry plumbing fixture, then penetrate the wall to run to the fixtures. Concealing the piping inside the walls requires more work, wall damage, and drywall patching for this method, and exterior exposed pipe must be insulated. Also, dogs love to chew off the pipe insulation where it is exposed at the outside walls.
The two standard choices for replacement pipe material are CPVC (cream-colored hard plastic) and PEX (flexible plastic, white or color-coded, red or blue, for hot and cold lines). Most plumbers consider CPVC to be the better choice, since it is a time-tested material and PEX is newer. However, PEX has the advantage of being able to bend around corners and uses barb-type crimp fittings that are easier to install.
Every plumber will have their own take on what is the best way to repipe your home, and you should talk to at least two that have been recommended by a friend or neighbor before deciding on who to use. It’s important to get a clear understanding of how much of the new piping will be concealed in the walls and what areas will have piping running across the wall surface when interviewing a prospective plumbing contractor.
Surface-mounted pipe inside a bathroom or kitchen cabinet is acceptable to most people, but you may not like the idea of pipes running along the walls of rooms or closets where it is clearly visible. It is cheaper to surface-mount piping, so you may choose to live with it in the laundry, for example.
Also, make sure you know how much repair the plumber will do for the openings made for the new piping and how it will be done—a patch piece of plywood over the wall opening versus a seamless drywall repair that is repainted, for example. Also, will the old pipes just be cut off at the wall, with pipe ends exposed, or will all evidence of the old piping in the wall be removed.
At the completion of the work, ask the plumber to give you a copy of the building permit for the repiping, with the final inspection approval noted on it. Homebuyers nowadays want to see closed-out permits for all work done to the home, and having a copy on hand will save you aggravation later when it’s time to sell your home.
Also, see our blog post Can you live in a house while the plumbing is being replaced?
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