Tracy Young is a co-founder of PlanGrid , an app that lets construction companies store blueprints and documents on mobile devices. Since going through the YC’s Winter 2012 batch, PlanGrid has grown from a team of 4 to 40 and now hosts over 9 million blueprints in their cloud. Prior to PlanGrid, Tracy was a construction field engineer and helped build and deliver several hospitals and heavy civil projects. She also spent time managing coordination of MEPF systems and bidding projects. She jokes that, with PlanGrid, she went from working for one superintendent to hundreds of thousands of them.