The Robins had to overturn a 12-point deficit in the second half to secure a 28-18 win.
Sandercock told Sky Sports News: "Full credit to Salford because they had a great completion rate in the first half. We dropped a lot of ball and full credit to them for their half time lead.
"The second half still wasn't great but our defence was really good and I knew if we could stop them from scoring we'd be okay. It was pleasing to get the win.
"It was a good defensive display in the second half. We turned the screw well and in the end we did enough to get the win."
The result leaves Hull KR sixth in the Super League table.