Sorry, I didn't make that very clear.... I'm only putting a backsplash behind my cooktop and was wondering how high it should be for safety reasons. Thanks again...

You need to check the specs for your range to see what clearances you need to combustible surfaces. I would guess at least 18" because that's usually how high cabinets on the side of the range need to be but I'm not sure that's enough behind the range. You might well want the stainless to go all the way up to the bottom of your range hood. To be honest, this is the first I've heard of a range up against wood walls.