Chimney Crown and Crack Repair in Cherry Hill, NJ

A cracked crown can be repaired when the slab underneath is sound, and it is rebuilt when the slab is crumbling, loose or shaped so that it holds water. Fine cracks in a solid crown are cleaned out and sealed with a flexible coating made for masonry. Many crowns on postwar houses were never true crowns, though. They are a skim of bricklayer's mortar spread over the top course, nearly flat and tight against the flue tile, and that shape fails twice over: mortar does not hold up well lying exposed to weather, and a flue tile grows and shrinks with heat while the slab around it stays still.

A rebuilt crown follows what New Jersey's residential code asks of a masonry chimney: a concrete, metal or stone cap sloped to shed water, with a drip edge and a caulked bond break around any flue liners. The slope sends water outward, the drip edge drops it clear of the brick face, and the bond break lets the tile move without cracking the new slab. A Colonial Revival stack in Haddon Heights that carries two flues gets a break around each one.

Cracked joints are repointed: the failed mortar is raked out to sound material and new mortar is packed back in, in layers, to the profile of the joints around it. On a prewar stack the decision that counts is the mix. The National Park Service's repointing guidance holds that new mortar has to be softer and more vapor permeable than the brick it sits in, because a hard joint forces the stress and the moisture into the brick, and the brick faces then break away. Postwar chimneys in harder brick tolerate a stronger mix, though the idea of matching what is already there still applies.

A crack that passes through the brick calls for more than new joints. Cracked or spalled units are cut out and replaced with the closest match in size and color, and courses that have shifted above the roofline are taken down and relaid on a sound bed. Mortar wants mild weather to cure, so crown pours and repointing are easiest to plan from spring through fall.

A crack points to a bigger problem when it is growing, when it runs through the brick, or when it shows the chimney has moved. Fine shrinkage lines across a crown are common and can often be sealed. A crack running from the flue tile out to the edge of the crown is different, because it hands water straight to the top courses. Stair-step cracks that follow the mortar joints down the side of a stack, a vertical split through the brick itself, or a section above the roof that has started to lean all point to something larger than weathering.

Binoculars on a dry day will show a lot from the lawn, and a second look after rain shows more. Dark patches that stay wet longer than the rest of the stack, white salt staining under the crown, brick faces that have popped off and mortar sand in the gutter all mark where water is moving. A gap opening between the chimney and the siding is a separate matter. A stack pulling away from a house usually has a problem at its footing, and mortar at the top will not close it.

No, not for long, because a patch covers the opening and leaves the cause in place. Roofing tar on a crown, caulk along a joint and a thin coat of cement over a whole chimney all look like repairs for a season, and all of them can trap water behind a skin it cannot escape through.

Three causes are worth ruling out before any mortar is mixed. Water at the top is the usual one, from a crown with no overhang or a flue with no cap. Water from the side is the second, where flashing has lifted and wets the courses above the roof. The third comes from inside the flue, on houses where the furnace now vents out a side wall and a lone water heater condenses in a masonry flue sized for two. Chimney cleaning shows the state of the liner, and chimney repair covers the flashing and flue work if that turns out to be the source.

It can, when the repair changes how the chimney looks from outside. Haddonfield asks for a Certificate of Appropriateness for alterations to a building's exterior appearance in its historic district, with the Historic Preservation Commission reviewing the design and the Planning Board giving final approval, and the borough's zoning officer answers borderline questions. Repointing that matches the old joints reads differently from a crown rebuilt in a new shape, so raise it before the work is scheduled. In Moorestown, exterior changes to buildings on the protected stretch of central Main Street and part of Chester Avenue go to the Historic Preservation Commission first, and Olde Marlton in Evesham is a locally regulated district. For a larger masonry job anywhere, ask the town building department whether a permit applies.

The repair starts with a free estimate built on what can be seen from the roof and the firebox, with photos of each crack and a plain account of what can wait and what cannot. AMG Duct Cleaning Cherry Hill is veteran owned, licensed and insured under NJ HIC 13VH13654300, and it handles crown and crack work in Cherry Hill and across Camden County and Burlington County.