We have a concrete patio under our elevated deck and when it rains you can’t sit out on the patio for the rain coming down between the deck boards. I’m thinking of putting some corrugated panels on the bottom of the deck with spacers on one end so the water will roll off and we can sit out there during the rain. Any other ideas welcomed. Thanks.

I would think the main goal would be to be sure the water didn't sit on the corrugated panel and make contact with the deck boards. I would add a spacer at the high end as well, just make the low end spacer thicker.

Of course when the space gets full of ice it will need to have good support and hopefully doesn't overload the deck.

How about a roof on the upper deck?

They make stuff just for that use. Check for under deck ceilings on the Lowes of Home Depot type sites.

I did this with plastic corrugated panels. The deck above had joists that were already pitched so I fastened pressure treated firring strips to the bottoms. I then attached the corrugated panels to the firring strips. I also added a gutter to catch the rain water and divert it to where I wanted it to go.

It worked extremely well with only a few drops here and there. Make sure your screws are straight and you shouldn't have a problem with that.

Collect the runoff in barrels and use to water your flowers or vegetables.