Q:

I am rebuilding some brick piers that extend above and below grade. What’s the proper way to waterproof the piers to prevent the mortar from deteriorating?

Michael Gonzales, Pulaski, TN

A:

Matthew Scolforo, staff engineer for the Brick Institute of America in Reston, Virginia, replies: The rate of deterioration of mortar is influenced by the length of time the brick masonry remains wet. Above grade, your piers do not require waterproofing; in fact, it is a good idea to leave them exposed to allow more rapid drying.

However, brick masonry that hasn’t been properly waterproofed below grade absorbs water from soil and can remain wet for a very long time. Wet soil will also keep brick piers saturated well above grade, a phenomenon called rising damp.

Below-grade waterproofing methods can extend the life of brick masonry considerably by avoiding prolonged saturation of the piers. One of the more common and least-expensive waterproofing techniques is first to parge the brick piers below grade with a 3/8-in. coat of one part portland cement and three parts sand by volume mixed with water. Let the parging cure for at least seven days, then coat the piers below grade with black foundation sealer. You can buy foundation sealer by the bucket at your local hardware store. Coat the piers from the top of the footings to just above grade, maybe an inch or two. The combination of cement parging and foundation sealer below grade will substantially reduce the amount of water migration from the soil into the brick piers. Consequently, the life span of your brick piers both below and above grade will increase.