How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
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How can I tell what type of plumbing pipe I have?
Saturday, August 18, 2018
Identifying all the different types of pipe in your home requires a little detective work, because most homes are originally built with multiple pipe materials: one for water and a second type—or sometimes a combination of two types—for drain pipes.
Over the years and with remodeling and repairs, newer types of pipe may have been added. So if your home is more than about forty years old, you likely have four or more different pipe materials. The newer pipes are usually the most visible, under the sinks and at the water heater. But often there is different pipe used in the original construction of the home which is at least partially hidden from view in the walls, under the floor and in the attic.
So take a look in the attic with a flashlight and pull back the escutcheon plates (a metal ring that covers the opening where a pipe penetrates the wall) to look behind them where you can, and see if you have older pipe still in place, but hidden from view. A black or gray rubber “transition coupling” with clamps (shown at right and below) peeking out from the wall at the escutcheon plate under a sink is a sure sign there is older pipe lurking inside the wall.
Here’s a list of the different pipe materials, with descriptions:
•• Copper - Copper is the same color as a new penny when first installed, then gradually transitions to the dark brown of an old one after a few years. Oxidation can cause greenish areas, and galvanic corrosion will make a powdery crust at connections to other types of metal pipe and valves. It has been used for water pipe since the 1930s, so copper is the tried and true, dependable choice.
Copper was predominant water supply pipe in our North Florida area from the ‘70s through 2000. However, acidic water or soil can cause premature failure, and it is more expensive to install than plastic pipes like CPVC and PEX. Today it is only used as water pipe, but up until the late 1960s it was also installed as drain pipe in better quality construction.
Copper has a life expectancy of 50 to 70 years or more, but pitting of the interior of the pipe can shorten the lifespan to just 20 years in areas with “aggressive” (very acidic) water, or water with any of several other combinations of ph, hardness, and contaminant factors.
•• Galvanized Steel - Galvanized steel water pipe is gray metal color and, when tapped with a screwdriver, makes a metallic sound. It was a less-expensive alternative to copper up until the 1970s, when it fell out of favor due to its short lifespan of 40 to 50 years. It was used primarily for water piping, but sometimes as a drain pipe. Galvanized pipe corrodes on both the inside and outside surfaces as it ages, and galvanic corrosion can cause large powdery, cancerous-looking lumps where it is connected to copper piping, as shown in the photo below.
Some insurance companies will not issue a homeowner’s policy for a home with older galvanized steel pipe, and others require certification by a licensed plumber that the pipe is in good condition issuing the insurance.
PB (polybutylene) - Polybutylene is a flexible plastic pipe that is usually gray, but can also be blue or black, with copper crimped rings securing the pipe at connections. It is usually stamped with the marking “PB2110.” The two photos below show examples of PB pipe. In the second example, the pipe has been painted over, but the copper crimp ring makes it easy to identify anyway.
The piping was used in residential water supply piping from 1978 to 1995, but is no longer manufactured. It was billed as “the pipe of the future” at first, and its low cost and easy installation made it an alternative to traditional copper water piping. PB was especially prevalent in mobile homes manufactured during the 1980s and early 1990s, but we also see it installed in site-built homes of the same era.
Beginning in the 1980s lawsuits, claiming that defective manufacturing and installation had caused hundreds of millions of dollars of water damage from ruptured pipes, began to mount into the thousands. Although the manufacturers never acknowledged that PB pipe is defective, they eventually agreed to fund a class action settlement for just under a billion dollars to resolve homeowner claims. The period for filing a claim ended in 2007.
While the exact cause is uncertain, it is believed that the oxidants (such as chlorine) in public water systems react with the plastic, causing it to flake and become brittle. As the integrity of the piping deteriorates, tiny fractures develop, which can expand over time and cause a sudden failure of the pipe and resulting water damage..
PVC (polyvinyl-chloride) - This white plastic pipe will have the letters “PVC” stamped on it and is often used for the water service piping to a home and for sprinkler system piping, but is not approved for use inside as water pipe and not rated for use with hot water. But it is used extensively for drain piping, as shown below.
CPVC (chlorinated polyvinyl-chloride) - This pipe looks similar to PVC, but is a cream-color and turns to light tan as it ages. It is the most popular water pipe for new homes in our area. It will be marked “CPVC” on the pipe, as shown below.
PEX (cross-linked polyethylene) - A flexible plastic pipe that is white, red or blue. When red and blue, the colors are used as coding for the hot and cold lines. It is often used as a replacement water pipe in older homes because its flexibility makes it easy to fish through existing wall cavities. If you look carefully, you should be able to find the letters PEX imprinted on the side of the pipe.
Cast Iron - This pipe is recognizable by its black finish and the bulge at the end of each pipe section, called a “hub,” that the adjacent pipe fits into. It was used up until the mid-1960s for drain pipe only and is still available, but rarely used in new construction. When it corrodes all the way through and starts leaking sewage, like in the photo of the crawl space below, it’s not pretty.
ABS (acrylonitrile-butadiene-styrene) - A black plastic pipe that is only used for drain systems. It was more popular about 30-years ago, and we seldom see it used in new construction today.
Which pipe is best? It depends on which plumber you ask. In our area, PVC is the drain pipe used for all new construction, but in other parts of the country ABS is standard. CPVC is the most often used water pipe, but the newer PEX pipe is gaining in popularity, and copper is considered the gold-standard for quality pipe by some contractors.
Here’s the approximate time range in which each pipe has been manufactured:
- Copper - mid-1930s to present
- Galvanized Steel - 1900 to mid-1970s, still available but rarely used for new construction
- PB (polybutylene) - mid-1970s to mid-1990s
- PVC - (polyvinyl-chloride) - 1970 to present
- CPVC (chlorinated polyvinyl-chloride) - 1960 to present
- PEX (cross-linked polyethylene) - Available beginning in mid-1960s. Wide use began around 2000
- Cast Iron - 1900 to mid-1970s, still available but rarely used for new construction
- ABS (acrylonitrile-butadiene-styrene) - mid-1950s to present
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Here’s links to a collection of our other blog posts about PLUMBING PIPES:
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