Dryer ventilation through concrete tube

Question

We recently discovered that our dryer vent duct terminates in some kind of concrete tube before exiting the house.

This is a picture from the outside (sticking my phone into the vent).

I don't think that concrete is foundation but I also cannot figure out what this concrete is there for.

My understanding is that U.S. code calls for the duct starting at the Laundry room wall/ceiling/floor to be a 4" round rigid 28ga sheetmetal duct all the way to the termination point on the exterior. IRC M1502. (I'm quoting from a comment someone made on a different post).

Is this exit through the concrete a fire hazard and/or to code?

Are there any legitimate reasons it would be set up like this?

Does that ducting beyond the cement look like the proper material?

Do you have any recommended fixes?

Thank you!

Answer 1

It looks like a tube that was cast into the foundation using some sort of temporary cylinder form. (possibly a length of steel duct was cast in the wall and the ripped out at some later time)

Is this exit through the concrete a fire hazard and/or to code?

code requires sheet metal, (and by using traditional units and measurements indirectly implies that the metal should be steel) Concrete is generally more fire-resistant than steel.

Does that ducting beyond the cement look like the proper material?

it looks like flexible plastic-and-wire ducting, so no

Answer 2

Is this exit through the concrete a fire hazard and/or to code?

It is not fire hazard, concrete is safer then metal

Does that ducting beyond the cement look like the proper material?

It should be metal not plastic