On an older Manhattan building the stone usually sits above the brick and at its base. Limestone sills and lintels, a carved band at the floor lines, sometimes a whole limestone front, and granite where the wall meets the sidewalk. When one of those units cracks or loses its face, the repair has to suit that stone, not just fill the gap.
Manhattan’s move to light-colored stone came around 1900. The city’s 2007 designation report on the Henry Seligman Residence at 30 West 56th Street, finished in 1901, describes its limestone front standing in striking contrast to the older row houses beside it, as changing taste turned toward Beaux-Arts design. Limestone sills, lintels, banding and whole fronts from that period are still on buildings across Manhattan.
As a stone repair contractor in Manhattan, we work on limestone and granite and decide the repair one unit at a time. A patch rebuilds a small loss in the face. A dutchman repair cuts out a larger damaged area and sets a new piece of stone into the original. A whole new unit goes in only when the old one cannot be saved. Choosing between those three, stone by stone, is what limestone restoration means on an older Manhattan front.
Four points from the General Services Administration’s technical procedures for historic limestone, written for the federal government’s own historic buildings.
GSA’s procedure for patching damaged limestone starts by cutting back to sound stone, scoring the surface so the patch has something to grip, and undercutting where possible. The patch goes on slightly proud of the face and is tooled down after seven days, so on a Manhattan sill it reads as part of the stone.
A dutchman, in GSA’s words, is any new or salvaged stone fitted into the existing facade stone. It suits larger losses, or ones that would show. The damaged area is cut to a rectangle with square corners at least 2 inches deep, and the joint at the face of a Manhattan stone is held to 1/8 inch.
The same procedures call for stainless steel, Type 302 or 304, for every pin, anchor and wire that holds stone, locked mechanically as well as bonded. Where old anchors behind a Manhattan facade have rusted, GSA’s procedure for resetting limestone strips them back and replaces any that are unsound with stainless steel.
New limestone has to suit the old in quality, color, pattern and texture, and GSA calls for its face to be dressed to resemble the stone beside it before it goes into the wall, not after. On a Manhattan facade, that is the difference between a repair that disappears and one that shows from the street.
Each damaged stone on the Manhattan facade is looked at on its own, sills, lintels, banding and base, to decide whether it needs a patch, a dutchman or a new unit. A single elevation often needs all three.
Small losses in limestone or granite are patched to the surrounding face. Larger damaged areas are cut out and fitted with a dutchman, so most of each Manhattan stone stays where it was set when the building went up.
A unit too far gone for a patch or a dutchman is replaced with new stone chosen to suit the facade. Every other stone on the Manhattan front stays original.
A limestone front in Manhattan was cut and carved for its own building, often more than a century ago, and no new stone carries those years on its face. That is why the order of repair matters. A patch where the loss is small, a dutchman where it is larger, and a new unit only where nothing else will hold. Worked that way, a Manhattan facade can be repaired many times over and still be mostly the stone it was built with.
Sardar Restoration Corp. proudly serves stone repair & repointing services in Manhattan and the nearby areas:
For stone elsewhere in the city, see stone repair NYC, and for the rest of our brick work on the island, brickwork contractor Manhattan.
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A dutchman is a new piece of stone set into an old one where part of it has broken away. GSA’s technical procedures define it as any new or salvaged stone fitted into the existing facade stone. On a Manhattan facade, the damaged area is cut square and the new piece dressed before setting.
Often, when the loss is small. GSA’s procedure for limestone repair cuts back to sound stone, scores the surface so the patch grips, and undercuts where possible. The patch goes on slightly proud and is tooled to the surrounding face once hard, which on a Manhattan facade saves the rest of the unit.
About a week in GSA’s procedure. The patch is put on slightly higher than the stone around it, left to harden for seven days, and only then cut back and tooled to the adjacent surface. Finishing a Manhattan patch at the same visit would mean shaping material that has not hardened yet.
When the loss is large or would show. GSA notes a dutchman is sometimes recommended for large spalls, or spalls that would be visually detracting, where a patch would read as a patch. On a Manhattan sill or lintel at eye level, a piece of real stone usually ages more like its neighbors.
Because rusting steel swells as it corrodes. NPS Preservation Brief 42 notes that rusting reinforcement spalls the surface of cast stone, and iron anchors behind natural stone corrode the same way. GSA’s procedure for resetting limestone replaces unsound anchors with stainless steel, which on a Manhattan facade stops the same damage coming back.
Usually, depending on the crack. A crack or loss in part of a unit can often take a patch or a dutchman, while a unit split right through may need replacing. The GSA procedures behind this page were written for historic federal buildings, and on older Manhattan fronts they keep original stone wherever it holds.
It is replaced with a new unit. GSA’s procedures call for new stone that suits the existing in quality, color, pattern and texture, dressed to resemble the stone beside it before it is set. On a Manhattan front, only the units that cannot take a patch or a dutchman are replaced.
