Chimney Services in Hamilton Township (Mercer County), NJ

What the numbers suggest for chimneys in Hamilton Township

Census estimates put 29% of Hamilton Township's 37,628 housing units in 1940 to 1959 and 32% in 1960 to 1979, with 14% from before 1940. Only about a quarter were built in 1980 or later. Chimneys from those earlier decades are typically masonry, often with clay tile flues, so the condition of the brick and the condition of the flue both come into play; The parts of a chimney, top to bottom lays out how they relate.

About 74% of occupied homes heat with utility gas, 18% with electricity and 6% with fuel oil. Where a household has switched to electric heat or to a furnace that vents through the wall, the chimney can be left with nothing attached and still face every winter. An idle chimney still needs its top kept closed to water, a point the Academy covers in its page on fireplaces nobody uses.

Detached homes make up 63% of units, with 10% attached, 9% in two- to four-unit buildings and 17% in larger buildings. Attached homes sometimes share one chimney structure, so work on one side can involve the neighbor. These numbers are township-wide and say nothing certain about any single chimney.

Why the top of the chimney wears first

Above the roof line, a chimney stands in rain, wind, sun and frost on all four faces, with no heated house wrapped around it. The Brick Industry Association's maintenance note singles out chimneys, along with parapets and copings, as parts of a building that face more severe exposure and may need repair sooner. The parts involved, from the top down:

• Crown. The concrete or mortar slab on top of the brick. Once it cracks, water reaches the masonry below; see crown coating vs. crown rebuild.
• Mortar joints. Joints in the top courses erode and open, letting more water in.
• Brick. Saturated brick can crack and spall as it freezes and thaws.
• Structure. Eventually courses loosen, the top section leans or separates, or the flue tile above the crown shifts.

Repair, partial rebuild or full rebuild

The choice turns on how much sound masonry is left and whether the structure has moved.

• Repair fits when the brick is sound and the damage is limited to the crown, some joints or a handful of bricks: crown repair, repointing or replacing individual units. In BIA's definition, repointing means raking out the damaged mortar to an even depth and filling the joint with new mortar.
• Partial rebuild fits when the top courses are loose, widely spalled or out of line but the chimney below the roof is sound. The damaged section is taken down to solid masonry and relaid with a new crown.
• Full rebuild comes up when cracking, movement or lean runs through most of the chimney. See chimney rebuilding and restoration.

A rebuild is also the moment to deal with what caused the damage: a properly built crown, a cap, new flashing at the roof line, and a new liner if the old flue tile is damaged. After a storm, CSIA calls for a Level 2 inspection following an external event likely to have damaged the chimney, and it names weather events among them. Our repair or rebuild guide goes deeper.

Local questions

Sources

1. U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates (tables B25034, B25040, B25024), via Census Reporter
2. Brick Industry Association, Technical Note 46: Maintenance of Brick Masonry (PDF)
3. Brick Industry Association, Technical Note 7: Water Penetration Resistance, Design and Detailing (PDF)
4. CSIA: The Three Levels of Chimney Inspections