Flaking or popping brick (spalling) and white powdery stains (efflorescence) both mean water is moving through your chimney's masonry. Spalling happens when trapped water freezes and breaks off the brick face; efflorescence is salt left behind as water evaporates. The fix is to stop the water source and repair damaged brick.
Efflorescence (white stains)
Water dissolves natural salts in brick and mortar, carries them to the surface and evaporates, leaving a white residue. It can be brushed off, but it will come back until the moisture source is fixed.
Spalling (flaking brick)
When saturated brick freezes, the water expands and pushes the face of the brick off. Spalled brick lets even more water in, so the damage accelerates every winter.
Where the water comes from
- Cracked crown or missing cap
- Worn mortar joints
- Failed flashing
- Non-breathable sealers or paint trapping moisture inside
How it's fixed
- Fix the water entry point (crown, cap, flashing)
- Replace spalled bricks and tuckpoint joints
- Apply a breathable masonry water repellent
More questions
Is efflorescence dangerous?
Not by itself, but it is a warning sign that water is moving through the masonry, which leads to spalling and leaks.
Need a local professional?
Chimney Champs has been a local chimney company for 13 years. We provide chimney repair & masonry in your area. Call (856) 300-9215 for a free estimate.
Sources & further reading
- NFPA 211 — Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances (National Fire Protection Association)
- Chimney Safety Institute of America (CSIA)
Keep reading
- 9 Signs Your Chimney Needs Repair
- Why Is My Chimney Leaking? 6 Causes and How to Fix Them
- Chimney Flashing Explained: Why It Leaks and How It's Fixed
- Chimney Crown vs. Chimney Cap: What's the Difference?
- Prefab Fireplaces and Rusty Chase Covers: A Guide for Newer Homes
- How Often Should You Clean Your Chimney?