Will this stop a leak from a 1/2” hole on cement wall?

Thank you for the question, Sandra. The OSI QUAD Window, Door & Siding Sealant may or may not be well suited for the intended use depending upon if the repair is inside or outside the home. This product is not recommended for interior use due to solvent vapors. A better alternative might be the OSI QUAD MAX product for your intended repair. -The Henkel/OSI Team 1-800-624-7767