If more than 50% of the sill is gone, a mortar repair may not be sufficient. In these cases, an "indent" or "piecing-in" repair is required. This involves cutting away a rectangular section of the damaged sill and inserting a new piece of matching sandstone, secured with stainless steel pins and lime mortar. While more labor-intensive, this method provides the most durable and aesthetically pleasing result for historic properties. Maintenance and Protection
For shallow repairs, a stone restoration mortar tinted to match the original color is ideal. Apply the mortar in layers, building it out slightly beyond the original profile of the sill. Avoid "feather-edging," where the mortar thins out to nothing at the edges; instead, create a clean, square-cut "key" for the mortar to sit in. Once the mortar has reached a "leather-hard" consistency, use a damp sponge or a finishing tool to texture the surface, matching the surrounding masonry. Managing Large Scale Erosion sandstone sill repair
To ensure successful sandstone sill repair, it is essential to: If more than 50% of the sill is
A 19th-century stone building in a coastal town had suffered significant damage to its sandstone sills due to weathering and salt damage. The repair project involved: While more labor-intensive, this method provides the most