Chimney Cap Installation in Cherry Hill, NJ

A brick stack takes a cap fastened to the flue tile or to the crown, while a factory-built flue takes only the cap made for that system. On masonry, a single-flue cap clamps to the outside of the tile. Where a stack holds two flues of different heights, as many prewar Haddonfield and Collingswood chimneys do, a wider multi-flue cap sits on the crown and covers both, which also shelters the crown itself. That wider hood looks different from the street, a point worth remembering in a historic district.

Factory-built fireplaces follow other rules. New Jersey's residential code says they are installed according to their listing, and it bars decorative shrouds at the top of those chimneys unless the shroud is listed and labeled for that specific system. So a Mount Laurel or Evesham homeowner cannot pick any cap from a shelf. The maker's label, usually found inside the fireplace, identifies the system, and the replacement has to suit it. The chase cover under that cap is a separate piece, and on many houses of that age it is what has rusted through. A cover formed with a raised center and a drip edge sheds water where a flat one lets it pool.

The cap has to fit the flue's outside dimensions and leave at least four times the flue's outlet area open under the hood. That four-to-one rule comes from New Jersey's residential code for rain caps on masonry chimneys, and a spark arrestor screen carries the same requirement, along with mesh openings no larger than half an inch and no smaller than three-eighths. Those limits exist for a practical reason: a cap set too low or a mesh too fine chokes the draft, and on a chimney venting a gas water heater or furnace, poor draft can push exhaust back into the basement.

Height matters along with width. The hood has to clear the top of the tile by enough to keep wind-driven rain out and let smoke leave, and a tall tile on an old stack can rule out a cap that fit the neighbor's chimney. The code also calls for the screen or cap to be removable so the flue can be cleaned, which is why a cap should never be cemented in place. Any cap that goes on a wood-burning flue will gather soot and creosote on its mesh over time, so it gets checked at each chimney cleaning.

It can, depending on the address, since a historic commission or a community association may come first. In Haddonfield's historic district a cap in a new style or material may count as a change to the exterior, so ask the zoning officer early. Olde Marlton in Evesham and the protected part of Main Street in Moorestown have review rules of their own. In townhouse rows around Mount Laurel, the association often owns what sits above the roofline, and approval comes before any ladder goes up.

Evesham has one more consideration. About 55 percent of the township lies in the Pinelands Management Area, and the Pinelands Commission tells residents to install a spark arrester of non-corrosive material on the chimney, have the chimney inspected for soot at least twice a year and clean it at least once a year. Chimney swifts set the calendar in masonry stacks everywhere else, since they are protected and a cap cannot go on over an active nest, so that job waits until the birds leave in late summer.

Replace a cap when rust has opened holes in the hood or mesh, when the fasteners have let go, or when wind has shifted it off square. Galvanized steel caps, common on older repairs around Cherry Hill, give up first, and rust streaks down the brick or the siding are the sign you can see from the lawn. Stainless steel holds up longer in smoke and weather, and copper is a choice where the look of an older house calls for it. A loose cap is a hazard in high wind, so a rattle from the roof is worth a look.

Bent mesh, a nest under the hood or heavy soot on the screen also justify a visit. Replacement is a good moment to look over the crown, the top of the tile and the flashing, since all of them are within arm's length. If the crown below is breaking up, a new cap has nothing sound to sit on, and the crown work goes first.

Yes, because an unused flue takes the same rain as a working one, and it dries more slowly with no heat passing through. Gloucester Township houses with a fireplace nobody has lit in years still collect nests and weather at the top of that flue, and two-flue chimneys in Haddon Heights often have one working flue beside one that has sat idle for decades. Water entering the idle side soaks through to the working side, so the whole stack pays for it.

A cap will not fix a split crown or lifted flashing, since those are separate paths for water, and chimney repair may still follow. What it does is close the largest opening on the chimney. A bare brick stack in Moorestown is usually worth capping, after checking the design rules above if the building sits in the protected Main Street district. Every cap starts with a free estimate from AMG Duct Cleaning Cherry Hill, which is veteran owned, licensed and insured.