Vandermade prepped at Mater Dei High School in Santa Ana, California. He was a 1998 Super Prep All-American, USA Today All-USA honorable mention, Prep Star Dream Team Top 100, Super Prep All-Farwest, Prep Star All-Western, Long Beach Press-Telegram Best in the West honorable mention, Orange County Register Fab 15 second team, Tacoma News Tribune Western 100, Cal-Hi Sports All-State first team, All-CIF Southern Section first team, All-CIF Division I first team, Los Angeles Times All-Orange County, Orange County Register All-Orange County first team and All-South Coast League first team as a senior at Mater Dei. He did not allow a sack in 1998 as a left offensive tackle. On defense, he had 26 tackles with 2 sacks. Mater Dei went 13-1, won the CIF Division I championship and was ranked No. 2 nationally by USA Today.