Local chimney waterproofing in Nassau Village-Ratliff

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.

More is not better

A heavier coat of repellent can seem like better value. BIA's note says the coverage rate is critical, because putting on too much can cut the breathability of the masonry, and breathability is the whole reason for choosing a penetrant over a film. The maker of the product we use gives a coverage range per gallon that depends on how porous the surface is, and very dense brick takes less than soft brick. We work within that range, keep track of how much each face has taken, and record it in the job notes so the next treatment can be planned from real figures.

The splash test for when to reapply

You can check whether a chimney's treatment is still working without any tools beyond a spray bottle or a garden hose on a gentle setting. Wet a patch of each face. Brick that is still protected throws the water off in beads and keeps its dry color; brick that has lost its protection turns darker within seconds as it soaks the water up.

We run that test on every face, since the face that takes the most weather wears first. Only faces that absorb get another coat, which saves product and avoids stacking coats where they are not needed. The results, face by face, go into the job notes.