Case Studies

Stone masonry repair

9th April 2019
Stone repair

Redevelopment of the former Barbourne College of Art and Design in Worcester, into 60 one and two bedroom retirement apartments has seen sector specialist and long term client of Plastic Surgeon, McCarthy & Stone call on the repair specialist’s service to deal with badly eroded sandstone masonry.

The challenges

Stone frontage repairAs part of its commitment to conserving the historic streetscape on Worcester’s Barbourne Terrace, McCarthy and Stone is retaining the existing frontage to the former college, despite much of the structure being in a very poor state of degradation.

A century of exposure to the extremes of the British climate, including rain penetration and the freeze-thaw cycle during harsh winters had left much of the stonework degraded. Dozens of stones had suffered significant cracking while others were pockmarked with holes and soft spots; and many corner blocks were missing their sections of their arris.

Investigation by the project team had concluded that many of the stones were in such a poor condition that quotes were sought from stonemasons for their replacement; which could have entailed extensive dismantling of wall sections to execute the work. As an alternative to this costly and disruptive process, Plastic Surgeon’s Midland Region was given the opportunity to tender for repairing the masonry in-situ; and a quote accepted for a total of four weeks work by the company’s experienced Finishers.

The highlights

Stone housing wall repairTwo of Plastic Surgeon’s most experienced Stone Finishers were allocated to the work following full assessments of Health & Safety considerations and the best method statement.

They began operations by cutting back the cracks to expose solid stone and achieve a good key. They then built back the depth of the repair using special repair mortar, tinted to match the original sandstone using Plastic Surgeon’s System 120 pigments.

The shape and surface texture of the blocks, measuring up to three feet in length, was achieved using a variety of metal and plastic hand tools before the entire area was oversprayed using the company’s Screedcoat system. The Finishers then blew in patterns of brown and black sand into the still wet Screedcoat in order to produce an aged appearance matching the untouched stones.

Key outcomes for clients

  • 70 of the old sandstone blocks were successfully repaired in-situ, avoiding the disruption of having to dismantle large sections of the street elevations, and the very high charges connected with employing stonemasons.
  • Throughout the four week contract Plastic Surgeon’s senior sales and operations staff for the region kept in touch with the client and visited site to ensure that the work was progressing smoothly and to everyone’s satisfaction. Ultimately, the standard of the workmanship will have to undergo the scrutiny of the new residents and the local heritage inspectors.
  • The repairs were completed within the original timeframe quoted.
  • The repair option has kept the consumption of materials and therefore the environmental footprint of the work to a minimum.

I had made use of Plastic Surgeon when working for another construction company, and it became clear here that it would have been a very big task for a stone mason to replace some of the areas which were damaged: involving taking down a lot of good stonework above. They are achieving a very good finish – it has definitely been worth doing as an alternative approach, and we’re very happy with the work: which is being carried out in a coherent manner.

Simon Houldsworth

Site Manager for McCarthy and Stone

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