What is this?

[Tim Ganey]

Anyone know what this black/rusty goo is? This exterior wall is opposite a kitchen where a gas stove is installed. I'm assuming this is a gas stub.

[John Kogel]

Anyone know what this black/rusty goo is? This exterior wall is opposite a kitchen where a gas stove is installed. I'm assuming this is a gas stub.It is a serious stain.

With no other info, I'd call for more investigation. If it is just rust, there is a leak in the wall somewhere. If there is tar in there as well, they need to find the source and fix it.

[Jerry Peck]

It appears to be a threaded steel gas pipe protruding through a Portland cement stucco exterior wall. The staining is likely the result of both the piping and the metal lath rusting due to improper installation and sealing.


If it is just rust, there is a leak in the wall somewhere. If there is tar in there as well, they need to find the source and fix it.

I agree with both of the above in that it looks like a leak and they need to find the source and fix it, which means (as Aaron said) it is due to improper installation and sealing.