Chimney waterproofing in Fleming Island by local experts

Silanes on dense surfaces

Of the clear repellents, silanes have the smallest molecules. BIA's note explains that the small size helps them get into dense materials, and that they are supplied at high concentrations of active ingredient. The reaction that makes them water-repellent goes fastest on alkaline surfaces like concrete and concrete block, which act as their own catalyst.

On less alkaline clay brick, some products carry an added catalyst to help. Where a chimney has a very dense brick, a block section, or a concrete element that needs treatment, a silane or a blend led by silane may suit it better, and we explain the choice made.

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.

Cleaning the brick before treatment

A repellent has to reach the pores, and anything sitting on the surface blocks it. BIA's note is plain that the wall must be clean when the product goes on, since heavy dirt reduces penetration and shortens the life of the treatment. Chimney brick is cleaned gently: loose salt brushed off dry, dirt and growth scrubbed with a stiff fiber brush and water, and cleaning products used only where the brick maker's guidance allows them. Pressure washing at high settings can drive water deep into the brick and damage joints, and it adds days of drying before treatment can start.