1 Hiring someone to repair and seal your basement interior can run $250-$1,000 or more; if the project also includes outside excavation plus installing a waterproof barrier and footer drains, the total cost starts around $5,000-$10,000, but can run $11,000-$15,000 or more. Hiring someone to do this can be another $50-$150 or more depending on what's involved in the project. 2  If you don't have rain gutters on your home, install them. 3  If you have gutters, extend the downspouts.