The pad trick I picked up from a guy in Bakersfield that saved me on 3 jobs last month
I used to just staple pad down and call it good, but this old installer showed me to flip the pad so the waffle side faces up on concrete. I tried it on a rental in Fresno with a slab that had a couple low spots, and the carpet laid way flatter with no ripples after 2 weeks. The reason it matters is the waffle side grips the carpet backing and lets it breathe, so you don't get that bubble effect in humid rooms. I've done 6 jobs since then and not one callback, which never happens for me in summer. Anyone else been taught the opposite? I'm curious if it holds up on stairs too.
Waffle side up makes even more sense on stairs now that I'm thinking about it. Those little bumps grab the backing on every step edge so the carpet can't slide or stretch when people are going up and down all day. I did a two story last week with the pad flipped and the nose of each tread held tight, no lifting at all after a few days of the family stomping on it. Only thing I'd watch is the glue or staples, you still gotta tack it good at the front of each step or that grip won't save you. Definitely trying it on the next stair job.