Cracked Chimney Crown: What It Means on Your Home Inspection Report

Your inspector found cracks, crumbling, or other wear in the chimney crown, the slab across the top of a masonry chimney that surrounds the flue liner. It is also called the cap, splay, or wash. In its technical book Chimney Fires: Causes, Effects & Evaluation (2007 printing), the Chimney Safety Institute of America (CSIA) explains the crown's job: close off the space between the flue liner and the chimney wall, shed rainwater clear of the chimney, and keep moisture out.

The crown is a known weak spot. The same book said failed or inadequate crowns are among the more common causes of chimney deterioration. Crowns are typically formed by spreading a thin layer of the mortar used between the bricks across the top of the chimney, and because mortar doesn't weather well used that way, CSIA said, those crowns deteriorate rapidly and develop cracks that let moisture into the chimney.

Why It Matters

Water is the threat. In a 2010 advisory, CSIA said water causes more damage to masonry chimneys than fire, and listed what water getting in can lead to: broken brickwork, rusted fireplace dampers, rotted wood and ruined wall coverings, cracked flue liner systems, and even deteriorated central heating systems. It added that water damage to chimneys is usually a slow process that is easily ignored until problems have become quite serious. A failing crown also sends water to the edge of the chimney, where, the book said, it runs down the wall and hastens erosion of the brick and mortar.

There's a fire-safety question to rule out, too. CSIA lists cracks in exterior masonry among its nine signs that a chimney has had a fire, along with cracked or collapsed flue tiles. It says a chimney damaged by a fire can endanger a home and its occupants, and that chimney fires can happen without anyone noticing. So have the inside of the flue checked, not just the crown.

Urgent (beyond repair-soon): loose or missing chunks of crown or brick, a leaning chimney, water stains or dampness around the fireplace or chimney inside the house, or any sign of a past chimney fire. Don't use the fireplace until a CSIA-certified sweep has inspected the chimney, and ask whether a furnace or water heater that vents into it is safe to run.

What to Do Before Closing

• Ask the inspector what they saw, how (from the ground, a ladder, or the roof), and for photos. Under the InterNACHI standards of practice, one of the standards home inspectors work under, inspectors look at the readily accessible and visible parts of a chimney and aren't required to inspect the inside of the flue or perform an NFPA-style chimney inspection.
• Book a Level 2 chimney inspection with a CSIA-certified chimney sweep. CSIA's Level 2 procedures (revised 2019) recommends one when a property is being sold. It includes going on the roof to inspect the crown and flashing, plus a video scan of the chimney's interior, which is how cracked flue tiles or water damage inside get found.
• Talk to your real estate agent about asking the seller to repair it or offer a credit within your inspection contingency. The sweep's written report and estimate give that conversation something concrete.

What to Do After You Move In

The sweep, or a mason, repairs or rebuilds the crown and fixes any damage the inspection found. CSIA's 2010 advisory called a cast crown with an expansion joint an ideal long-lasting replacement for a sand-and-mortar wash. Its book cites brick-industry recommendations: concrete several inches thick, sloped away from the flue, extending past the chimney's face so water drips clear, and not bonded to the flue liner, so the liner can expand; CSIA's procedure notes NFPA 211 requires that bond break.

Ask about the rest of CSIA's 2010 water advice too: a well-designed rain cap over the flue keeps out rain and nesting animals, and flashing seals the roof-chimney joint so water doesn't reach ceilings and walls.

Then keep up the yearly inspection. CSIA follows the national standard, NFPA 211, which reads: "Chimneys, fireplaces, and vents shall be inspected at least once a year for soundness, freedom from deposits, and correct clearances. Cleaning, maintenance, and repairs shall be done if necessary." Our fireplace safety guide covers booking it and what else to check before the first fire.

Can You Fix It Yourself?

No. A crown repair is masonry work on top of a chimney, on the roof. CSIA said in 2010 that annual inspections and preventive chimney maintenance are best left to a qualified chimney professional, like a CSIA Certified Chimney Sweep, and our DIY vs. hire-a-pro guide puts chimney masonry in the hire-it-out column. From the ground and inside, you can:

• Scan the top of the chimney with binoculars for new cracks, crumbling, or pieces on the roof.
• Check the damper for rust and the walls and ceiling around the chimney for water damage; CSIA lists both among the damage water causes.

Frequently Asked Questions

Is a cracked chimney crown a deal breaker?

Not usually by itself. What matters is what the water has done inside: to the flue liner, the brick, the damper, and the framing around the chimney. That's what the Level 2 inspection is for, before your contingency ends.

Do I need a chimney inspection if I won't use the fireplace?

Yes. CSIA says the yearly NFPA 211 inspection applies even to a chimney you rarely use, because animals may nest in the flue and the chimney can deteriorate on its own. A cracked crown lets water in whether or not you light a fire.

The Bottom Line

A cracked crown is a slow-acting problem: it lets water into the chimney, and water does more damage to masonry chimneys than fire, CSIA has said. Book a Level 2 inspection with a CSIA-certified sweep before closing, talk to your agent about a repair or credit, and then keep up the yearly inspection. See more findings in our inspection report decoder.

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