12 complete symptom paths42 guides and 60 questions in each1,460 Grade A articlesOne searchable, connected knowledge library140 official sourcesEvidence context with explicit limits
Symptom dossier

White powder on a basement wall

A crystalline white deposit is often efflorescence: salts carried to the surface by moving moisture.

Urgency profileInvestigate
Use timing, location and checks to separate competing explanations.

The deposit records moisture movement

The important question is why water or vapor is moving through the masonry.

Document before cleaning

Photograph its height and shape and compare after rain.

ObserveDistinguishControl sourceVerify
Living dossierPublished knowledge is connected and improved as new cases, images and outcomes are added. Updated 2026-07-20.