Water destroys more chimneys than fire ever will. In the Pacific Northwest, where annual rainfall exceeds 37 inches and months of persistent dampness keep masonry saturated, chimney waterproofing isn't optional—it's essential protection.
Waterproofing is one of the most cost-effective chimney investments you can make. For $200-500, you dramatically reduce the water absorption that causes the majority of chimney damage—damage that costs thousands to repair once it takes hold.
Brick and mortar are porous. In the Pacific Northwest, chimneys rarely dry completely from October through May. This persistent saturation enables several destructive processes:
Water absorbed into masonry expands by 9% when frozen, forcing cracks wider and progressively breaking down the structure through repeated cycles.
Water dissolves calcium compounds in mortar over time, weakening the structure and creating white efflorescence deposits on brick surfaces.
Dampers, flashing, and liner connections corrode when exposed to persistent moisture, weakening components and creating penetration gaps.
Water migrates inward causing wall staining, drywall damage, paint deterioration, mold growth, and flue liner damage from outside in.
Professional chimney waterproofing uses breathable sealants that prevent liquid water from entering masonry while allowing water vapor to escape from within. This distinction is critical.
Masonry always contains some internal moisture. A non-breathable coating (like paint) traps this moisture inside where it migrates deeper, freezes, and causes damage from within. Breathable waterproofing lets internal moisture escape as vapor while blocking external liquid water from entering.
Clean and dry chimney surface. Remove dirt, efflorescence, moss, and loose material for proper adhesion.
Fix any mortar failure, crown damage, or brick problems before waterproofing. Never seal over existing damage.
Apply waterproofing agent to all exposed masonry by spray for even coverage. Multiple coats ensure thorough protection.
Allow 24-48 hours of dry weather for proper curing. Schedule during appropriate weather windows.
Homeowners sometimes consider painting their chimney instead of waterproofing. This is counterproductive:
Quality breathable waterproofing products typically last 5-10 years depending on exposure conditions. South-facing and west-facing chimney surfaces may need reapplication sooner than sheltered surfaces.
We recommend reapplication every 5-7 years for chimneys in the greater Seattle area. This maintenance schedule provides continuous protection at minimal cost.
Breathable sealants specifically formulated for masonry chimneys, not hardware store water sealers.
Clean, sound surfaces ensure proper adhesion and penetration of waterproofing agent.
Identify and fix existing damage before waterproofing. Sealing over damage is counterproductive.
Professional spray application ensures even, thorough coverage including hard-to-reach areas.
Chimney waterproofing requires working at roof height around the full chimney perimeter. Professional equipment and training ensure safe application while protecting you and your property.
Protecting chimneys from Pacific Northwest moisture since 1979.
Highest industry credential ensuring expert knowledge.
Professional breathable sealants formulated specifically for chimneys.
Inspection, repair, and waterproofing from one certified company.
In our climate, waterproofing pays for itself by preventing the water damage that drives most chimney repairs. Protect your chimney before moisture damage develops—or stop existing moisture problems from getting worse.
45 years of certified expertise protecting chimneys from Pacific Northwest moisture.