Hi everyone,

I'm trying to figure our how to to describe the substance that is spread on a roof of a building to stop the penetration of the rain.

Is that pitch, tar or asphalt ?

What is the difference between these three words ?

Could one of them be more useful in American/British English ?

Thank you!
There is some overlap in these terms, and they may seem very similar (dark in color and fluid when heated). However, each comes from a different source. Pitch is generally from plants (sap or resin). (Coal) tar comes from the burning of coal. Asphalt comes from petroleum.
However, tar and pitch are sometimes used as loosely the same.

As far as roofs go, I would not use "asphalt"--you may have an asphalt driveway or asphalt shingles on your roof, but not straight asphalt. I would say you would cover your roof with roofing tar.