Local chimney waterproofing in Fernandina Beach

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.

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.

Repellent does not seal the roof joint

The roof joint around a chimney is sealed with metal: step flashing woven into the roof covering and counterflashing let into the masonry above it. When that metal lifts, rusts or loses its seal, water runs down between the chimney and the roof framing, without touching the brick faces a repellent protects. Stains on a ceiling near the chimney, or wet framing in the attic beside it, send us to the flashing before any treatment is priced. Flashing repair is its own job, and damage to the roof covering itself is referred to a roofer.