Local chimney waterproofing for Lake Shore homes

Absorption through the faces versus water through openings

Masonry takes on water in two distinct ways. Rain can soak slowly through the faces of brick and mortar, spreading as a dark, damp patch across a whole wall. Or it can run in through a specific opening: a crack, an open joint, a failed crown or a gap along the flashing. The Brick Industry Association treats clear repellents as a tool for the first problem, reducing how much the faces absorb, and says little can be expected of them against the second.

So on a chimney we sort the two before anything is proposed. Openings are repaired with mortar, brick or metal. Absorption through sound faces is what a treatment is for.

Applying from the bottom up

On a vertical face, the maker's directions for our product start at the bottom and work upward, using a low-pressure sprayer with a fan nozzle or a roller. Each pass floods the brick until a little excess runs down below the wet area, and a second wet application follows within minutes, before the first has soaked away. Starting low means any run-down falls onto brick that has not been treated yet, instead of streaking across finished work. Each face is completed in one continuous session so there are no lap marks where one day's work meets the next. Corners and the edges of the crown are cut in by brush where the spray cannot reach cleanly.

Painted or glazed brick is left out

The maker's directions for the repellent we apply exclude painted brick and glazed brick or tile. Paint already forms a film on the face, and a glazed unit has a fired, glass-like surface that the product cannot enter. Spraying either one wastes material and can leave a haze. Painted or glazed sections of a chimney are therefore masked off and left untreated. If paint on the chimney is blistering, peeling or taking the brick face with it, that points to moisture trapped behind it, and what to do about the paint is set out as a separate decision.