6 tips for working on plumbing in historic homes

For plumbers, the toughest part of repairing or renovating a historic home is dealing with the unknown.

What problems lurk behind those thick, aging walls and ceilings, or under the bathroom floors? How can you get a handle on the job if you don’t know what kind of pipes you have, what shape they’re in or how they may have been altered over the years?

Every home is different. But a little planning can help you identify and address common plumbing concerns for your customers.

1. Learn when the home was built.

The age of the home and its pipes will determine what plumbing issues you can expect.

In the early 1900s (or earlier) – lead pipes were commonly used in homebuilding. Lead pipes can last a century — but not without leaching into the drinking water. Replace all lead pipes to comply with modern safety standards.
Before the 1960s – cast iron drain pipes were common. Minerals in the water cause these pipes to slowly corrode, making interiors rough and jagged and leading to clogs. Drain cleaners can make the problem worse. Rust spots aren’t always an immediate concern, but replace the pipe if you see evidence of a crack along the seam.
In the 1960s – galvanized steel was popular for water pipes, though copper was also used. Galvanized pipes can last 20 to 50 years, but they will eventually corrode and leak along the threads where they attach to fittings. Galvanic corrosion can also occur when existing galvanized water lines have been repaired with dissimilar metals (such as copper), reducing water flow rate and pressure.

2. Look for clues about piping.

Sometimes you can’t be sure what types of pipes an old home has until you start repairs.

Looking under the sink won’t help — if any newer pipes have been installed, that’s where they are likely to be. Here are some ways to get a better idea of a home’s pipe materials, and their condition:

  • If the basement has an open ceiling, you may be able to see the water lines. Look at the exposed drain-waste-vent (DWV) lines in the basement to determine piping material(s).
  • Try to find the service line entering the home. What materials are used on the service line before and after the water meter? What pipe materials are visible on the incoming and outgoing water lines for the water heater?
  • A good test for pipe corrosion: Ask the homeowner if water flow is noticeably slower when the washing machine (or toilet) and shower run at the same time. If it is, you may need to replace the pipes.

3. Determine permit requirements.

Fixing leaks doesn’t require special permits; but replacing pipes or remodeling plumbing in a historic home may. Check with the city to see if the home is held to the design guidelines for residential historic districts. If so, the homeowner will need to have an architect draw up a plan for the proposed work and secure necessary approvals (along with any required permits) before work begins.

4. Access pipes with care.

Old homes were built to last — that’s why they’re still here. But their solid construction makes pipes hard to access. Walls typically have three layers: plaster, a metal screen and wood laths. They are hard to cut through, and blades can get caught in the metal screen. Even cutting a small section can cause cracks in the surrounding plaster. If you use drywall to repair them, shim it to match the existing surface – or call a specialty contractor.

5. Check sewer lines.

Underground pipes, particularly if they’re made of cast iron or clay, allow root growth and decay. To confirm pipe integrity, run camera equipment through the home’s sewer line to create a video of the interior.

6. Dispose of contaminants properly.

Older homes may have asbestos in the ceilings and flooring (or wrapped around pipes) as well as lead paint, which you can test for using an inexpensive kit. Removal and disposal of these materials requires training and certification.

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