On a stone building in New York, the mortar is the part meant to be renewed and the stone is the part to protect. Joints can be raked out and refilled many times over a building’s life. A carved sill or a block of granite, once lost, cannot be put back in the same piece.
Most stone repair on a New York building begins with the joints, not the stone. When mortar fails, water reaches the back of the stone and starts the damage that later needs patching or replacement. Stone repointing deals with it first, and on wide stone joints NPS Preservation Brief 2 notes that old mortar may need to come out to a depth of several inches before new mortar goes in.
As a stone repair and repointing contractor in NYC, we repair before we replace. Failed joints are repointed, damaged stone is patched or pieced in with new stone, and only a unit that cannot be saved is replaced. That order follows the National Park Service’s guidelines for rehabilitating historic buildings, and it is the order a stone restoration company should work in on an older front.
New York buildings use more than one kind of stone, often on the same front.
Each fails in its own way, so each is repaired in its own way.
Limestone trim and whole limestone fronts are common on pre-war NYC buildings. Our stone repair Manhattan page covers them in depth.
Brownstone is a soft sandstone that flakes away from its face. On a New York row house it is handled under brownstone restoration NYC.
Granite is the toughest stone on most NYC buildings. Its joints at steps and bases take heavy water and traffic, and often need attention first.
Cast stone is precast concrete made to look like stone, widely used across New York by the early 20th century, NPS Preservation Brief 42 notes.
Fieldstone in old walls and foundations is laid with wide joints of uneven shape. North of the NYC line, see stone repair Westchester.
Four principles from the National Park Service that keep a stone repair from taking more of a building’s stone than it has to.
The Park Service’s rehabilitation guidelines advise against removing sound mortar to repoint a whole building for a uniform look. On an NYC front, raking out joints that were still working only exposes more stone edges to damage, so repointing follows the joints that have actually failed.
The same guidelines recommend duplicating old mortar joints in width and in profile. Stone joints run from hairline seams between dressed blocks to wide beds on rougher work, and on a New York building a joint widened or reshaped during repointing changes how the whole stone reads.
Patching, piecing-in and consolidating come before replacement in the guidelines, and replacing a whole feature when repair would do is listed as not recommended. NPS Preservation Brief 42 makes the same point about cast stone, much of which is replaced in NYC and elsewhere when small damage could have been repaired.
When a stone is too far gone, the guidelines call for limited replacement in kind, or a compatible substitute where the same stone is not feasible. NPS Brief 2 adds that replacement stone needs the same care in matching as any replacement unit, so a new piece on a New York facade has to suit the old work around it.
We look at which stone the NYC building is made of, whether the joints or the stone units have failed, and where the water is coming from. NPS Brief 2 puts repairs to drainage and other sources of damage ahead of repointing, so those come first.
Failed joints are raked out until sound mortar is reached, which on wide stone joints can mean several inches, and refilled. Damaged stone on the New York wall is patched, or the damaged part is cut out and a new piece of stone set in its place.
A stone unit that is too far gone to patch or piece in is replaced. The new stone is chosen to suit the NYC building around it, as the Park Service's guidelines call for, and everything else stays.
A stone front in New York can go through several rounds of repointing and still be wearing the same stone it was built with. That only happens when the repairs are done in the right order. Joints first, because they are meant to be replaced. Then patches and new pieces set into the damaged stone. Then, only where nothing else will hold, a new unit. Work the other way round, swapping stone that could have been saved, and a building loses the one part of itself that cannot be bought again.
We take on stone restoration in NYC across Manhattan, the Bronx, Queens and Brooklyn, and the same stone repointing reaches older buildings in Westchester County and Yonkers.
Everything else we do with brick and stone in the city is on brickwork contractor NYC.
Browse our gallery to explore the outstanding projects we’ve successfully completed, highlighting our expertise.
Until sound mortar is reached, which depends on the joint. NPS Preservation Brief 2 notes that on stone masonry with wide joints, old mortar may need to come out to a depth of several inches. Narrow joints between dressed stone on an NYC front need far less before new mortar goes in.
Often, yes. The National Park Service’s rehabilitation guidelines recommend patching, piecing-in or consolidating damaged masonry before replacing it, and limit replacement to extensively deteriorated or missing parts. On a New York building, a patch or a new piece set into the old stone keeps the rest of the original unit in place.
No, only the ones that have failed. The Park Service’s guidelines advise against removing sound mortar to repoint a whole building for a uniform look. On an NYC front, joints that are still doing their job are left alone, and the repointing follows the failed ones across the wall.
Cast stone is precast concrete made to look like natural stone, and much of it can be repaired. NPS Preservation Brief 42 notes that a lot of historic cast stone is replaced when small spalls could be repaired with matching composite mortar. On a New York building, replacement is for severe damage only.
When it is too far gone to patch or piece in. The Park Service’s guidelines call for limited replacement in kind of extensively deteriorated parts, or a compatible substitute where the same stone is not feasible. On an NYC facade, the new unit is chosen to suit the stone around it.
Whatever let the water in. NPS Preservation Brief 2 puts repairs to drainage and other sources of deterioration ahead of repointing, because new joints fail quickly if water keeps reaching them. On a New York building that can mean gutters, leaders, copings or roof edges, sorted before the masonry work starts.
