Q. My house was built in the ’40s and has a cinder-block foundation. On the inside, it has paint that’s peeling. Some of the blocks are crumbling, but the problem is not deep, less than an inch.

With a stain-blocking primer on the walls, you then can apply the wall paint of your choice. Unless there continues to be moisture migration through the blocks, that should be the end of the staining.

A painting contractor will charge $404 to clean, prepare and stain 1,200 square feet of concrete walls (or about a 25- by 50-foot area with 8-foot-high walls). You can do the job for $95 - the ...