Moss lifts shingle edges and holds water against the roof deck. Treat annually (zinc or approved treatments), brush gently — never pressure-wash composition shingles — and prune shade branches that feed the growth. North slopes need double attention.
Full gutters overflow into fascia, siding, and foundations. Clean twice yearly minimum under canopy, verify downspouts discharge well away from the house, and watch for the drip lines that reveal failures.
Standing water under the house is common and fixable: grading, downspout extensions, vapor barriers, and sump systems in stubborn cases. Musty smells upstairs usually start downstairs.
Seattle homes grow condensation mold without airflow: bath fans on timers, kitchen venting used, and furniture pulled off exterior walls in winter. Ventilation is cheaper than remediation.
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