Restoring the Hiatt Baker Estate's Historic Bath Stone Folly: Stone Cleaning, Repairs, and Repointing Techniques

The Bath Stone folly on the Hiatt Baker Estate near Bristol stands as a remarkable piece of history, showcasing craftsmanship from a bygone era. Over time, exposure to weather, organic dirt, and vandalism has taken a toll on this architectural gem. Restoring such a structure requires careful attention to detail and respect for traditional methods. This post explores the key steps involved in cleaning, repairing, and repointing the Bath Stone folly to bring it back to its former glory.

Historic Bath Stone folly on Hiatt Baker Estate before restoration

Cleaning Stone with Therma Tech Technology

One of the first challenges in restoration is removing layers of organic dirt, moss, and graffiti without damaging the delicate Bath Stone. The team used a Therma Tech cleaning system, which applies controlled heat and steam to the stone surface. This method gently lifts grime and biological growth while preserving the stone’s natural texture.

Therma Tech cleaning offers several advantages:

• Avoids harsh chemicals that can erode stone

• Minimizes water usage compared to traditional pressure washing

• Effectively removes graffiti without abrasive scrubbing

  
  

This approach ensures the stone looks refreshed without compromising its integrity.

Replacing Large Hand-Crafted Cornices

The folly features large cornices that were originally crafted by hand, showcasing fine detailing and traditional stone masonry skills. Over time, some cornices suffered cracks and erosion, requiring replacement.

Skilled stonemasons carved new cornices from matching Bath Stone blocks, replicating the original designs. This process involved:

• Selecting stone with similar grain and colour

• Hand-carving details to match historic patterns

• Installing cornices with traditional fixing methods to maintain authenticity

  
  

Replacing these cornices restored the folly’s architectural character and protected the structure from further weather damage.

Stonemason hand-carving replacement Bath Stone cornice

Repointing with Lime Mortar

Repointing is essential to strengthen the joints between stone blocks and prevent water ingress. The restoration team used lime mortar, a breathable material that allows moisture to escape, reducing the risk of stone decay.

Key benefits of lime mortar repointing include:

• Compatibility with historic Bath Stone

• Flexibility to accommodate slight movements without cracking

• Preservation of the building’s original appearance

  
  

The mortar was carefully mixed and applied by hand, ensuring neat joints that blend seamlessly with the existing stonework.

Stone Replacement Including Ashlars and Window Cills

Some ashlar blocks and window cills showed significant wear or damage. These elements were carefully removed and replaced with new Bath Stone pieces cut to precise dimensions.

The process involved:

• Measuring and marking damaged stones for removal

• Sourcing Bath Stone from local quarries to match colour and texture

• Crafting replacement stones with attention to detail

• Installing new stones with lime mortar and traditional fixing techniques

  
  

Replacing these critical elements improved the folly’s structural stability and visual appeal.

New Bath Stone window cill installed on Hiatt Baker Estate folly

Restoring the Bath Stone folly at the Hiatt Baker Estate required a blend of modern technology and traditional craftsmanship. Using Therma Tech cleaning preserved the stone’s surface while removing dirt and graffiti. Hand-carved cornices and carefully repointed joints with lime mortar maintained the building’s historic character. Replacing worn ashlar blocks and window cills ensured the structure remains sound for years to come.