Chimney waterproofing in Fleming Island by local experts

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.

Waiting after the joints are repointed

New mortar in a joint is still hardening and still giving off water for days after it is placed. Coating it too soon can interfere with that cure and lock the moisture in. BIA's pre-coating checklist sets a floor of 72 hours for freshly repointed mortar and repaired sealant joints, and the maker of the repellent we use sets the same interval after tuckpointing or other repairs.

On a chimney that has just been repointed, treatment is therefore booked as a separate visit. Writing the cure period on the estimate keeps anyone from spraying on the same afternoon the trowels are put away.

Visibly dry brick and a rain-free window

For a penetrating product to soak in, the pores need to have room for it. The maker's directions call for clean, structurally sound masonry that is visibly dry, and they rule out wet or saturated surfaces. They also ask for a six-hour window with no rain expected, unless the treated wall can be sheeted with plastic. After a run of wet days, brick can look dry at the face while still holding water further in, so on the day we check the brick itself, pressing and looking at freshly scraped mortar, rather than relying on the forecast and the look of the surface alone.