Breathable Chimney Waterproofing

Why Masonry Soaks Water—and How We Stop It

Brick and mortar are porous. They wick rain, dew, and coastal mist deep into the wall. In winter, that trapped water freezes and expands, cracking crowns, popping brick faces, and eroding joints. On Long Island, wind-driven rain makes the top few courses and the crown work overtime. The goal of breathable chimney waterproofing is to dramatically reduce liquid water absorption while still letting interior vapor escape.

What “Breathable” Really Means

Not all sealers are equal. Paint-like films can trap moisture, which accelerates spalling and efflorescence. We use penetrating silane/siloxane systems that line pore walls, shedding liquid water but allowing vapor diffusion. This keeps masonry drier overall—especially helpful on exterior stacks with cold exposure.

Our Process for Long-Lasting Results

1. Inspect & prep: We evaluate the crown, cap, upper courses, and flashing. We clean surfaces so the treatment penetrates fully.
2. Fix first, then protect: We address failed joints with pointing, cracked crowns with a rebuild, and roof junction leaks with proper flashing before waterproofing.
3. Apply breathable treatment: Even, flood-coat coverage from the crown down to shed water while preserving vapor permeability.
4. Detail the top: A correctly sized chimney cap and sound crown keep vertical rain from overwhelming the brick below.
5. Document & cure: We provide photos and guidance on cure time and re-application interval based on exposure.

Symptoms Waterproofing Helps Prevent

• Spalling faces and crumbling corners near the top courses
• Persistent damp staining and white salt (efflorescence)
• Interior ceiling or chase stains after storms
• Rapid mortar erosion despite recent tuckpointing

Crown, Cap, and Flashing: The Leak-Stopping Trio

Waterproofing shines when the top-end details are correct. A sloped crown with drip edge throws water clear of the brick below. A properly screened, stainless cap blocks vertical rain and animals. Correct flashing moves roof water around the stack. Together, these upgrades reduce the workload on your masonry so the treatment lasts longer and performs better.

Will It Change How My Chimney Looks?

Quality breathable systems dry clear with minimal sheen. On darker, dense brick, you may see almost no change; on highly absorbent surfaces there can be a subtle deepening until full cure. We spot test first and protect surroundings carefully. If you want color correction or stain removal, we can discuss pre-treatment cleaning options.

Maintenance & Re-Application

Exposure, porosity, and salt air determine intervals. Many chimneys benefit from re-application every few seasons. We’ll recommend a schedule and show you simple checks (like controlled water drops) to gauge performance over time. Routine inspections help catch top-end issues before they shorten the life of the treatment.