On Dec 24, 12:21 am, "Edwin Pawlowski" wrote:

It may not be so bad with a straight pipe with no joints, but at some point
it had to come up from under the concrete right? It just has to have some
buildup of lint over time. I see that as being a big problem at some point.

The patio is raised, and the duct would be about two feet higher
the surrounding ground level.

However, after hearing the comments here, I am going to go up through
the ceiling and out the end of the attic. Total run: 25 feet, one 90
degree elbow in the attic.

Thanks to everyone for all the info.

Rick