Q.: Late last fall I poured an 18-inch monolithic foundation for a new garage, 20 feet by 36 feet with a 4-inch by 6-inch curb wall. I used a six-bag limestone mix with NYCON in it and have now decided that I would like a higher curb wall, adding about another 4 inches. Can this be done by simply forming up to where I want it to be and doing an overpour? What are the pros and cons involved? I live in northern Indiana, just off the southeast edge of Lake Michigan, so of course we have extreme freeze/thaw cycles to contend with.
A.: You can certainly add more concrete atop the curb walls. I would install some dowels to tie the two portions of wall together. About every 4 feet, drill a hole about 4 inches into the top of the existing curb and epoxy in a #4 rebar. Be sure to clean all the dust out of the drilled holes. Keep the top end of the bar at least an inch from the surface of the concrete, unless it is going to be indoors where concrete cover is not an issue.