Solid stone – 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 solid stone 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 require repointing (replacing the mortar)
  • mortar helps hold the stone wall together, fills joints and gives structural support. Different types of mortar are used, largely depending on the requirements of the specific project. Some types of mortar allow a wall to “breathe” while others don’t. The right choice and application of the mortar is crucial to performance
  • inappropriate mortar and/or inappropriate pointing can lead to moisture problems in a stone wall. 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 knowledge, skills, experience and tools 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

  • follow the recommendations in the first repair above

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Cause

Use of lime mortar

Repair

  • follow the recommendations in the first repair above

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Cause

Foliage (creepers, vines) growing on building

Repair

  • remove the foliage and identify the extent of damage and work required
  • follow the recommendations in the first repair above

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