Mark Philben -- Globe Correspondent

Q. Some time ago, I noticed yellow/brown stains that are about 1.5 feet by 0.5 feet in diameter on a bathroom ceiling, probably from a leak in the attic roof directly above it. I tried painting over it with “ceiling white’’ acrylic paint, but the stain is still visible although slightly lighter. Do I need to apply a sealant before repainting it?

A. You need to use a stain-blocker primer before painting over a stain, or it will bleed right through like you witnessed. There are many on the market. They state very clearly on the can that it is for stain blocking. You spot-prime with these products; they are not cheap, so you don’t want to prime the whole ceiling. The oil-based ones are best.

Q. When a new addition was added to our home, we could not pour a full basement foundation; we hit ledge about 5 feet down. Instead of hammering or blasting, we decided to live with the exposed ledge, pouring concrete but leaving a few mounds exposed. First mistake! We have a high water table, so seepage and water became a common occurrence. We have added an interior French drain along the perimeter, which has done a great job, but now the ledge areas, especially after a rainy 2021, have exacerbated the situation.

I think pouring concrete over the top (along with a vapor barrier and crushed stone contained by wooden forms) will help stop the flow. There is a well that directs the water to a sump pump. In addition to the new concrete on the ledge, I expect to create a 4-to-6-inch trench to direct water to the sump pump. We had limited success breaking up the ledge with a jack hammer to install the French drain, so I don’t think that is an option. Do you think my idea will work?

A. This is a tricky one. It sounds as if you had the right approach in the French drain, but the water table has crept up around the ledge rock.

I do not think encasing the ledge in concrete will help long term. One thing I have learned from experience is that water always finds a way and always wins if you try to just plug it and stop it. The best way to deal with the water in your case is to invite it in, capture it, and discharge it. The best long-term solution is to locate where it is coming up around the ledge, drill in that area to allow it to flow in, and then dig a trench to the sump pump. You had mentioned some variation of that. As always, consulting with a qualified basement drain company is a great place to start.

Mark Philben is the project development manager at Charlie Allen Renovations in Cambridge. Send your questions to [email protected] . Questions are subject to editing. Subscribe to the Globe’s free real estate newsletter — our weekly digest on buying, selling, and design — at pages.email.bostonglobe.com/AddressSignUp. Follow us on Twitter @GlobeHomes and Boston.com on Facebook.