Tubular traps require an accessible listed approved trap adapter-IRC 3003.1 & IRC 2704.1

No.

The Inspector and LazyPup have this one incorrect.

Trap adapters are not required under the IRC or IPC.

Trap adapters with slip joints may be installed on the trap inlet, trap outlet, and within the trap seal...and when they are installed, they must be accessible under the code sections lazypup noted...

But trap adapters are not required to be installed anywhere under the 2003 through 2009 International Residential Code or International Plumbing Codes.

All traps can be plumbed in place without mechanical joints.

Your neighbor does not have to change a thing.

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PS: I am a nationally certified IRC and IPC Plumbing Code Inspector

LazyPup does not have it wrong!

I stated that "Tubular Traps" require a trap adapter, however as Manhattan has pointed out, you may opt to use Pipe type traps, in which case they would be glued in and a trap adapter would then be placed on the input side of the trap to connect the tubular tailpiece to the trap.

The bottom line, a trap adapter is the proper transition fitting to connect tubular drain fittings to pipe whether the transition takes place before or after the trap.

Thanks guys.

For what it's worth, I'll report back next week when I see the existing set-up's.

lazypup said:
"The bottom line, a trap adapter is the proper transition fitting to connect tubular drain fittings to pipe whether the transition takes place before or after the trap."

No, a trap adapter is but one type fitting or method to connect tubular drains to pipe.

We still see some old-time plumbers who use 'sweat adapters' (soldered connections) for the transitions....and it is still an entirely acceptable method.

But back to the original post which states: "An inspector told homeowner that some of the lavatory sinks need trap adaptors installed underneath. Those sinks have been done and in use for over a year. Does code really require that?"

IF tubular traps are used with slip joints, then they would need to be accessible.

But there is no mention of 'tubular traps' at all in the original post. And under the IRC/IPC, nothing would need to be changed for an existing installation.

Nice try, anyhow, lazypup. :)

I had a first-hand look today. They happen to have tubular traps....that run right into trap adaptors. They are the PVC "female end" adaptors with a chrome compression ring (as opposed to ones with the plastic ones). So I don't know what the inspector thought he saw, but they look perfectly fine to me.