2008-09: Sandlak, the son of former NHL forward Jim Sandlak, played for the London Jr. Knights organization. In 30 games for the Minor Midget squad, Sandlak scored 13 goals and added 18 assists for 31 points while also picking up 112 penalty minutes. In 11 playoff games with this team, Sandlak scored 5 goals and added 7 assists for 12 points. He also played for Midget squad, picking up 1 assist in 4 games for that squad. Chosen in the first round, 11th overall, of the 2009 OHL Priority Selection by the Guelph Storm.
2009-10: In his OHL rookie season, Sandlak played in 61 games for the Guelph Storm. He scored 7 goals and added 8 assists for 15 points while also adding 61 penalty minutes. In 5 playoff games for that team, Sandlak picked up 1 assist. Sandlak played for Team Ontario at the 2010 World Under-17 Hockey Challenge, scoring 1 goal and chipping in 1 assist for 2 points in 6 games while also being the most penalized player in the tournament with 33 penalty minutes.
2010-11: Sandlak started the season with Guelph, playing in 22 games for that team. He scored 4 goals and added 3 assists for 7 points along with 25 penalty minutes. He was dealt to the Belleville Bulls in December, appearing in 34 games for that club. He scored 9 goals and added 7 assists for 16 points to go along with 44 penalty minutes.
Sandlak will return for his overage year with the Plymouth Whalers in 2013-14.