Stone veneer – crumbling mortar

Causes

Weathering

Mortar quality is poor – most commonly found in pre-1930s buildings

Use of lime mortar

Foliage (creepers, vines) growing on building

Listed under: Exterior, masonry, stone, cladding, walls, mortar, wall cladding, solid stone and stone veneer

Cause

Weathering

Repair

  • if the veneer forms part of an occupied building, address the problem without delay. Crumbling mortar can lead to leaks and weathertightness problems. The solution is likely to be repointing (replacing the mortar)
  • mortar holds stone masonry units together, fills joints and gives structural support. It is a paste that is typically made up of Portland cement, hydrated lime, sand and water. Different types of mortar are used on stone projects, largely depending on the structural requirements. The right choice and application of the mortar is crucial to the performance of the veneer
  • as with brick veneer walls, there are specific construction requirements for stone veneer such as providing gaps at the bottom to allow drainage
  • most homeowners should contact a stonemason for advice. Look for a mason who has completed an apprenticeship, is well experienced and ideally holds a qualification such as the New Zealand Certificate in Stonemasonry. There is also a New Zealand Stonemasons Association who can help you find a mason
  • you should only consider scraping out loose mortar and doing the repointing yourself if you have the skills and experience to do the job, or the job is on a relatively unimportant structure such as a low garden wall

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Cause

Mortar quality is poor – most commonly found in pre-1930s buildings

Repair

  • if the veneer forms part of an occupied building, address the problem without delay. Crumbling mortar can lead to leaks and weathertightness problems. The solution is likely to be repointing (replacing the mortar)
  • mortar holds stone masonry units together, fills joints and gives structural support. It is a paste that is typically made up of Portland cement, hydrated lime, sand and water. Different types of mortar are used on stone projects, largely depending on the structural requirements. The right choice and application of the mortar is crucial to the performance of the veneer
  • as with brick veneer walls, there are specific construction requirements for stone veneer such as providing gaps at the bottom to allow drainage
  • most homeowners should contact a stonemason for advice. Look for a mason who has completed an apprenticeship, is well experienced and ideally holds a qualification such as the New Zealand Certificate in Stonemasonry. There is also a New Zealand Stonemasons Association who can help you find a mason
  • you should only consider scraping out loose mortar and doing the repointing yourself if you have the skills and experience to do the job, or the job is on a relatively unimportant structure such as a low garden wall

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Cause

Use of lime mortar

Repair

  • if the veneer forms part of an occupied building, address the problem without delay. Crumbling mortar can lead to leaks and weathertightness problems. The solution is likely to be repointing (replacing the mortar)
  • mortar holds stone masonry units together, fills joints and gives structural support. It is a paste that is typically made up of Portland cement, hydrated lime, sand and water. Different types of mortar are used on stone projects, largely depending on the structural requirements. The right choice and application of the mortar is crucial to the performance of the veneer
  • as with brick veneer walls, there are specific construction requirements for stone veneer such as providing gaps at the bottom to allow drainage
  • most homeowners should contact a stonemason for advice. Look for a mason who has completed an apprenticeship, is well experienced and ideally holds a qualification such as the New Zealand Certificate in Stonemasonry. There is also a New Zealand Stonemasons Association who can help you find a mason
  • you should only consider scraping out loose mortar and doing the repointing yourself if you have the skills and experience to do the job, or the job is on a relatively unimportant structure such as a low garden wall

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Cause

Foliage (creepers, vines) growing on building

Repair

  • remove foliage, including the roots to avoid the problem recurring
  • further repairs, as above

 

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