How to keep squirrels from chewing on cedar deck?

I bought an motion-activated sprinkler and it worked to keep animals out of my garden, I bet this would help your situation too: https://amzn.to/2VYlOgj

Sprinkle red pepper flakes or place in a cap from an old medicine bottle. Squirrels get lost fast!

I found a repellent that resists rodents and deer and sprayed it onto my plants. I bet a liquid spray would get them to stop the chewing.

Hello there, Is it the edge they are chewing? If so had you thought to fix a metal edge strip??

motion sensor sprinklers are the least cruel & very effective; I think Ammonia will eat finish off deck as well as some essential oils. Try 100% pure peppermint oil