RickM wrote:
I am replacing a deck with a poured concrete patio.

The problem is that my dryer vents under the deck.

Does any see a problem using standard rigid aluminum ducts to extend
from my house out to the edge of the patio? I will be pouring concrete
on top of the 4" rigid vent.

I have thought of using PVC instead, but I would expect that would be
a hazard were the dust in the vent to ignite.

Missing the patio is not an option, since I would have to route the
vent through several floor joists.

Any better ideas?

I'd use PVC. It's cheaper. It will not burn and even if it did, it's under
concrete!

If you pour concrete on aluminum ductwork you risk crushing the pipe -
concrete is HEAVY.