Corrugated scrap can only be found while scavenging - It looks like rusted sheet metal and is almost always found on the beach - as well as containers, lockers, etc.
You need to SAVE every bit of it. Always take it with you and then when you return to your Home island, begin stockpiling it.
You will need to find (at minimum) 20 pieces of SCRAP across one playthrough. I made a giant scrap pile on my home island and waited until I had enough.
You can actually do this with a minimum of 13 pieces of scrap. You can simply destroy the shelves after you build them which will drop 1 piece of Corrugated Scrap each time that you can reuse. Thanks to TuKraZe for the tip.
Once you have enough, make a save, and then built and destroy 10 corrugated shelves for your house (at two scrap each) - that will unlock your achievement.