I have an 8-foot raised deck. I am going to strip the top horizontal
floor, then brighten it. Then I'll clean (w/ oxygen bleach) the rest of
the deck, including the undersides. Finally I will stain it with Defy
Epoxy Wood Stain (Cedar tone).

Question:
-Assuming I don't care about the color underneath the deck, do I need to
seal the undersides of the deck & steps, including all the joists
underneath the deck (perpendicular to my house), or can I just clean
them and leave it alone since the sun doesn't hit it, etc.?

If I need to seal underneath the deck, I'll need to order more Defy
stain/sealer...

Tnx