A stone entrance, a side service stair and the areaway of a landmarked Upper East Side townhouse — cleaned, rebuilt and repaved over late summer 2026.
The building sits inside the Upper East Side Historic District, designated by the Landmarks Preservation Commission in 1981 and extended in 2010. That changes how you work. On a landmarked elevation the answer is almost always repair in kind rather than replace: match the material, match the profile, and leave the street facade reading exactly as it did before anyone arrived. Nothing about this job should be visible as a repair.
It was also occupied throughout. Staff and visitors used the entrance every day, the building fronts a busy street, and there was no version of the job where the front door closed for three weeks. The work was staged so the entrance stayed in use.
The stone itself needed judgement rather than force. Marble and limestone clean up beautifully, but they are soft — too much pressure, or the wrong chemistry, and you etch the face permanently. Cleaning was worked back gradually rather than blasted, and masonry repairs were made in JAHN restoration mortar, a mineral system designed to match the parent stone in strength and vapour permeability instead of sealing it.
The service stair was the one element past saving. Its terracotta treads had broken back to the substrate and were holding water, so it came out entirely and was rebuilt in bluestone on a new concrete base.
Stage 1
The entrance steps
Marble treads under decades of soiling, with black anti-slip strips bonded across the face of the stone. Cleaned back to the marble, the veining returns and the entrance reads as the building intended.
Stage 2
The service stair
The side stair had lost most of its terracotta treads — nosings broken away, tiles missing, the substrate open to water. It was taken out and rebuilt in bluestone on a new concrete base.
Stage 3
The areaway
The passage down the side of the building had heavy staining to the limestone and a broken, ponding floor. Walls were washed down and the whole court repaved in bluestone laid to fall.
Materials
Repair mortar that matches the stone
JAHN is a mineral restoration mortar mixed to suit the specific stone it is going into. It is deliberately no stronger than the parent material and stays vapour-open, so moisture can still leave the stone rather than being trapped behind a hard cementitious patch — which is what causes a repair to blow the face off the stone it was meant to save.
It costs more than a bag of sand and cement. On a building like this one, using anything else is how you turn a repair into permanent damage.