
Moss on the chimney and mortar that never dries?
- Moss or green film on the crown and shaded faces
- Masonry that stays visibly damp from October to May
- Rust creeping across caps and screens
Why it happens in Washington: Western Washington chimneys rarely freeze and never dry: moss on the crowns, saturated mortar all winter, rusting metal. Seattle's own seismic programme names unreinforced masonry chimneys directly, which says what the older stock is made of. Water patience plus earthquake questions: that is the local pairing.
What fixes it, and what it costs
In maritime rain the enemy is patient water, not sharp frost: moss holds moisture against the crown, joints stay saturated, metal rusts from the wet side out. The maintenance that works is seasonal: moss off and crown checked in the brief dry window, repairs cured while cure is possible, stainless for the metal, and a breathable repellent once the masonry is sound and dry.
- Flexible seal over a sound crown
- $200–$500
- Localised patch repair
- $300–$700

























