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Mortar, Brick or Tile Pieces Falling Into Your Fireplace: What It Means
Finding crumbs of mortar, bits of brick or curved pieces of clay tile in the firebox is a sign that something inside the fireplace or chimney is breaking down. Stop using the fireplace until it has been checked.
Stop using the fireplace: do not light a fire if pieces are falling from the damper area, the smoke chamber or the flue. A damaged flue may not contain heat and smoke the way it should. Have a qualified professional inspect it first. See signs to stop using your fireplace.
What you might be finding
The material tells you roughly where it came from.
| What fell | Likely source | Why it matters |
|---|---|---|
| Gritty, sandy mortar crumbs | Mortar joints in the firebox, smoke chamber or chimney interior | Deteriorated joints can let water in and need to be assessed |
| Curved or flat pieces of reddish or buff clay | The flue liner (clay tile) | A cracked or broken liner may no longer contain combustion products |
| Small chips of firebrick | The firebox walls or floor | Worn firebrick and joints may need repair before more fires |
| Brick face flakes | Often the outside of the chimney, if found at the base | See spalling brick |
Why it happens
- Water. The Chimney Safety Institute of America (CSIA) white paper on chimney fires notes that frozen water admitted by a poor crown can damage clay liners. Moisture also weakens mortar, and home-inspection guidance says deteriorated mortar joints can crack, weather away or shed chunks.
- Settlement and age. The CSIA paper also lists settlement and impact as causes of liner damage, because clay tile is brittle.
- A past chimney fire. In laboratory heat-shock tests described in the CSIA paper, all liners cracked and some were badly broken, raising the possibility that pieces might fall out later. If you have had a fire in the flue, see after a suspected chimney fire.
What a professional checks
The key question is whether the damage is in the firebox or in the flue above it. A chimney inspection can answer this with a look inside the firebox and smoke chamber and a video scan of the flue. CSIA Level 2 inspection guidance calls for a video scan of the chimney interior, looking for cracks or gaps in the liner. The levels are explained in inspection levels 1, 2 and 3, and the process in chimney camera inspection.
It helps to keep a few of the pieces in a bag or take clear photos before sweeping up, so the inspector can see what came down.
Repair options
- Firebox mortar and firebrick. Home-inspection guidance says firebox joints should be no wider than 1/4 inch and use fireclay mortar. See firebox repair.
- Smoke chamber. Gaps and rough surfaces can be repaired; see smoke chamber repair and smoke chamber parging. Our Morristown project is an example.
- Flue liner. Per NFPA 211 as quoted by CSIA, a liner that has cracked or deteriorated so that it cannot contain combustion products must be removed and replaced, repaired or relined. Options are covered in flue liner repair and HeatShield options and clay vs stainless steel liners. See also chimney liners and HeatShield flue repair.
- The water source. If the crown or cap is letting water in, that is addressed too; see crown repair.
Our Jersey City project began with a Level 2 inspection and ended with a new liner and crown repair.
Frequently asked questions
Is a little mortar dust normal?
Any chunks, or crumbs that keep appearing, are worth having checked. Mortar that crumbles easily when poked is described in inspection guidance as a warning sign.
Can I patch it myself and keep burning?
We would not recommend it. If the damage is in the flue or smoke chamber, you cannot see it from the firebox, and a patch does not tell you whether the flue still contains the fire. Have it inspected first.
Does a chimney sweep cleaning fix this?
Cleaning removes deposits but does not repair broken tile or mortar. See what a cleaning visit includes.
Next step
Keep the fireplace out of use, save a sample of the debris, and request an inspection or call (862) 225-6529. AM Chimney Sweep is a registered (NJ HIC #13VH14312300) and insured New Jersey home improvement contractor.
Sources
- CSIA, Chimney Fires: Causes, Effects and Evaluation (brittle clay liners, frozen water and settlement as damage causes, cracked liners and falling pieces, NFPA 211 liner language)
- InterNACHI, How to Inspect Fireplaces, Stoves, and Chimneys (deteriorated mortar shedding chunks, firebox joint width and fireclay mortar, cracked liners)
- CSIA, Level 2 Inspection of a masonry chimney (video scan of the interior, checking the liner for cracks or gaps)