Returned to suite due to clients concern of water leaking from ceiling. I found that the return plenum box was not sealed with mastic and all 4 corners of the box were not sealed. These corners correspond with the wet spot on the ceiling tiles. Our client elected to seal the plenum box on the exterior side to help prevent future water leakage. I showed our client pictures and let him know it would take about 48 hours to completely dry. No leaks found on rooftop at this time.