What CSST is

CSST is thin-walled, flexible stainless steel tubing with a plastic jacket, usually yellow or black. It runs in long continuous lengths with fittings mainly at the ends, so it can be routed through attics, walls and floors with far fewer joints than rigid pipe. That is why it shows up in remodels and in new lines to kitchens, laundry rooms and water heaters.

Because the wall is thin, the manufacturers' instructions and the fuel gas code call for specific protections: bonding to the home's electrical grounding system, strike plates where it passes through framing, and approved fittings for that brand.

CSST at a glance

Looks like
Flexible tubing with a yellow or black plastic jacket
Used for
Indoor and attic gas runs to appliances
Not for
Direct burial in soil without approved protection
Must have
Bonding and protection per the manufacturer's instructions
Installed by
Trained installers; check the manufacturer's requirements

What bonding means

Bonding connects metal piping to the home's grounding system with a conductor and clamp so that stray electrical energy, such as from a nearby lightning strike, has a safe path to ground instead of arcing through the tubing. Many manufacturers specify a direct bond near where the gas enters the building. The exact method depends on the product and the edition of the code your inspector enforces.

Bonding is not something to guess at. It involves both the gas and electrical systems, so ask the plumber how it will be done and whether the inspector will check it.

Signs to look for in a home with CSST

These are reasons to have a licensed plumber or inspector take a closer look, not proof of a problem.

  • Yellow or black jacketed flexible tubing in the attic, garage or behind appliances
  • No visible bonding clamp and wire near the gas entry point or meter
  • Tubing lying on metal ducts, flues or other metal objects
  • Missing strike plates where tubing passes through studs near wall surfaces
  • Mixed fittings or tubing from different brands
  • Jacket damage, kinks or crushed sections

If you are adding or extending CSST

  1. Confirm the installer is qualified.Ask whether the plumber is trained on the specific CSST brand being used, and check their CSLB license at cslb.ca.gov.
  2. Plan the route.Keep the tubing away from sharp edges, hot flues and places it could be crushed or punctured.
  3. Bond and protect.Install bonding and strike plates as the manufacturer requires.
  4. Pressure test and inspect.Test the new run before closing walls, and schedule an inspection where a permit applies.

Questions to ask

  1. Which CSST product will you install, and are you trained on it?
  2. How and where will the tubing be bonded?
  3. Will the electrical side of the bond need anyone else involved?
  4. Is a permit required, and will the inspector check bonding?

Common questions

Is CSST unsafe?

CSST is an approved material when installed to the manufacturer's instructions, including bonding. Problems are mostly linked to missing bonding or damage.

Can bonding be added later?

Often, yes. A licensed plumber can evaluate the existing tubing and add bonding where it is missing.

Is the gas meter connection enough to ground CSST?

Not necessarily. Many manufacturers require a specific direct bond. Ask your plumber what the product calls for.

General information for Villa Park, not a quote or professional advice. In an emergency, call 911.