Why Hot Lime Mortar.

Why Hot Lime Mortar is the Only Choice for Heritage Restoration

At Salthouse Stonemasonry, we are fully committed to using hot lime mortar in all our heritage restoration work. This is not a preference based on fashion or convenience — it is the result of experience, research, and a deep respect for the way traditional buildings were built and maintained for centuries.

When it comes to conserving historic stonework, non-hydraulic hot lime mortar is the only option that truly respects the building’s original construction and ensures its longevity.

Why Non-Hydraulic Hot Lime Mortar Matters

Hot lime mortar has been used in building for thousands of years, long before modern cement or even hydraulic limes were introduced. It was the standard material for everything from cottages to cathedrals because it works in harmony with traditional building materials like natural stone and handmade brick.

It is breathable and flexible, allowing moisture to pass through rather than trapping it inside walls. This is crucial for the health of a building — trapped moisture leads to decay, frost damage, and eventual structural problems.

A non-hydraulic lime set occurs slowly, through carbonation, meaning the mortar remains soft enough to accommodate natural movement in the building without cracking the stone or brick. This is exactly how heritage structures were designed to function.

Why Hydraulic Lime or Cement Mortars Are Wrong for Restoration

We’ve seen too many period buildings suffer because someone insisted that hydraulic lime mortar or, worse, cement mortar was “good enough” for repairs. These materials set too hard and too quickly, creating a rigid bond that the surrounding stone cannot cope with.

The result? Stone edges spall away, moisture gets trapped behind impermeable joints, and the very fabric of the building starts to fail. Often, the damage caused by these “modern” repairs is far greater than the original problem they were meant to solve.

Do not let anyone pull the wool over your eyes and claim that these materials are acceptable for heritage restoration. They are not. The science, history, and decades of conservation experience all point to the same truth — non-hydraulic hot lime mortar is the only appropriate choice.

Conservation Means Working With the Building, Not Against It

Conservation is not just about making something look right. It’s about ensuring a building continues to function as it was intended, with materials that are compatible and sympathetic to its age.

Hot lime mortar offers:

• Breathability — allows moisture to evaporate naturally

• Flexibility — moves with the building instead of forcing cracks in the stone

• Softness — ensures the mortar, not the stone, takes the weathering over time

• Authenticity — matches the original materials used by the original craftspeople

  
  

By using hot lime mortar, we are not just fixing damage — we are continuing a tradition of care that has kept these buildings standing for hundreds of years.

Our Commitment at Salthouse Stonemasonry

We will never compromise on materials when it comes to heritage restoration. Every mix of hot lime mortar we use is produced in-house, using quality lime and carefully selected aggregates to match the existing work. This allows us to create repairs that are visually and technically in keeping with the original structure.

For us, the goal is simple: to ensure your building will still be here, strong and beautiful, for generations to come — and that starts with using the right mortar.

Final Word

If you own a period property or are responsible for a heritage building, remember this: the wrong mortar will destroy your stonework. The right mortar will protect it for decades, if not centuries. Non-hydraulic hot lime mortar is not an option among many — it is the choice for proper conservation.

At Salthouse Stonemasonry, we don’t just restore stone. We preserve history, one hot lime mix at a time.