Three questions first. Is your brick clean? Is it solid? Will it soak up water? Wash off dirt, moss and loose bits. Look for a white, salty crust. That is efflorescence, and it means water is moving through the wall. Splash some water on. If it beads, an old sealer may block the limewash.
Then fix or flag what is making the wall wet: cracked mortar, failed caulk, spilling gutters, dirt piled against the brick. Limewash lets moisture out. It does not fix the leak. Is your house from before 1978? Then your old paint can only be scraped or stripped when it is handled with lead-safe work practices, by a firm that holds certification under Washington’s renovation rules.