Intro:
You crawl under your house and see white, chalky stuff on the walls. Is it mold? Nope—it’s called efflorescence (fancy word, simple meaning). And it’s your crawlspace trying to tell you something: “I’m wet.”
Let’s break down what it is, why it shows up, and what you need to do about it.
What Is Efflorescence?
Efflorescence literally means “to flower out.” In plain English, it’s salt crystals that form on masonry when water moves through it and then evaporates.
Here’s the recipe for efflorescence:
Salts in the concrete or block wall
Water (or high moisture)
Evaporation that leaves those salts behind
The result? That white powder you’re seeing.
Why Is It in My Crawlspace?
Simple answer: water is getting through your foundation wall.
When it rains, water soaks into the ground around your home. If you live in the Carolinas (or anywhere with clay-heavy soil), your house is sitting in what’s basically a clay bowl. That soil acts like a sponge and creates what’s called a false water table—a mini reservoir pressing against your foundation.
Over time, the pressure builds (this is called hydrostatic pressure) and water finds the path of least resistance: your wall.
Is It Dangerous?
Efflorescence itself isn’t harmful—but the moisture behind it is. If water keeps seeping through:
Mold can grow on nearby wood
Blocks can weaken and even break down over time
Your air quality can take a hit
What Should You Do?
Improve exterior drainage – Gutters, downspouts, and grading matter.
Seal and control humidity inside – Vapor barriers, sealing vents, and a dehumidifier help.
For severe cases – You may need drainage systems or encapsulation.
Bottom Line:
Efflorescence is your early warning sign. It means water is getting in—even if you don’t see puddles yet. The sooner you deal with it, the better.
👉 Got questions? Drop a comment or check out my full guide: How to Obtain a Healthy Crawlspace (Complete Guide).
🔥 That’s the full 6-post series DONE!
