Most chimney problems on Long Island come down to water. It gets into cracks in the crown, mortar or brick, freezes, expands and makes the crack bigger. Ageless Chimney notes that Nassau County swings above and below freezing many times each winter, so that cycle repeats all season.
Three contractors’ prices, side by side
Long Island contractors publish fairly different numbers, so here are three side by side.
| Repair | Long Island Exterior Co. (May 2026) | Home Team Construction (Jul 2026) | Alec’s Construction (Aug 2026) |
|---|---|---|---|
| Chimney cap | $300 to $800 | $150 to $850 | $250 to $900, stainless |
| Crown repair | $500 to $1,500 | $200 to $700, sealing cracks | $400 to $900, sealant membrane |
| New crown | $1,000 to $3,000 | $800 to $2,500, poured | |
| Flashing | $800 to $2,500 | $300 to $1,800 | $800 to $2,500 |
| Repointing | $500 to $2,500 | $500 to $2,500 | $1,500 to $5,000 |
| Liner | $2,500 to $7,000 | $900 to $7,000 | |
| Rebuild above the roofline | $3,000 to $10,000 | $1,000 to $4,000, top section | $3,500 to $9,000 |
| Full rebuild | $8,000 to $20,000 | $4,000 to $15,000 | $10,000 and up |
The problems that cause most leaks
Flashing. The metal where the chimney meets the roof. Long Island Exterior Co. calls failed flashing the most common way water gets in around a chimney.
The crown. The cap of concrete on top of the brick. Alec’s Construction says many Long Island chimneys have a thin mortar skim instead of a poured crown, and it cracks within a few years. They call it the most common chimney failure they see.
Mortar and brick. Crumbling joints need repointing. Spalling brick, where the face flakes off, is caused by water freezing inside it. Ageless Chimney puts spalling repair at $1,000 to $3,500 for up to 100 square feet.
The cap. A missing cap lets rain, animals and debris straight down the flue. Long Island Exterior Co. warns that galvanized caps can corrode within a few years near the coast.
Warning signs
- water in the firebox after rain
- white staining on the brick
- crumbling mortar or flaking brick faces
- rust in the firebox or on the damper
- a stain on the ceiling or wall next to the chimney
Inspections
NFPA 211, the national fire code for chimneys, says chimneys, fireplaces and vents should be inspected at least once a year. The Chimney Safety Institute of America defines three levels:
| Level | What it covers | When |
|---|---|---|
| Level 1 | The accessible parts of the chimney, and a check that the flue is clear | Yearly, for a chimney in regular use |
| Level 2 | Level 1 plus attic, basement and a camera scan of the flue | When anything changes, when the house is sold, or after a chimney fire or severe weather |
| Level 3 | Removing parts of the chimney or wall to reach a suspected hidden problem | Only when a Level 1 or 2 points to one |
If you are buying or selling a house, that is a Level 2.
Permits
Long Island Exterior Co. says liners and rebuilds usually need a permit from your town or village. Ask who pulls it before you sign.
