Derry City & Strabane - Walls




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Walls not only provide shelter from the elements but also hold the building up! If they are kept dry it will not only ensure your house is comfortable to live in, it will help to minimise need for maintenance. However, inappropriate repairs to brick and stone can cause serious damage. Seek professional advice before undertaking any work and always consult a structural engineer if you have concerns about the stability of a wall.

Bricks and stone rely on the integrity and flexibility of the masonry pointing or mortar used to keep water out of a building. Look out for signs of delamination and degradation of stone and brick. Missing mortar, failed or washed out pointing, and cracked and open joints allow water penetration. This is particularly damaging when frost occurs. Walls can easily suffer long term damage due to inappropriate repairs or harsh cleaning.  Cleaning and repairs of stone or brick work should always be carried out under guidance from a qualified professional.

A render is often used to provide a protective finish to a wall and was traditionally lime based. Use of lime allows the wall behind to breathe as well as being flexible enough to accommodate movement in the building materials. Modern cement renders are harder and can trap moisture behind, forcing it into the building fabric. Hollow sounding or ‘boast’ areas indicate that the render has separated from the wall behind and needs to be repaired or replaced. Use of cement in render and repointing repairs should be avoided.

Trees growing close to walls, or sometimes from the base of the wall, should be carefully cut down as close to the base as possible and the stump treated to prevent further growth. Roots should be left in place, as removal will often cause considerable damage. Although unlikely, the wall should be occasionally monitored in case of any long-term local subsidence cracking.

Many older buildings are set close to mature trees. While these undoubtedly enhance the setting of a building, monitoring is essential.  Ash and Scots Pine, for instance, are particularly vulnerable to our increased storm events and can cause catastrophic damage to adjacent buildings. Often it is possible to have suitable trees ‘topped’ or ‘pollarded’ by a tree surgeon, thus retaining the visual asset and extending the life of the tree by many years.

In addition to shedding leaves annually, deciduous trees such as ash and sycamore exude a sticky substance in the spring. This will accumulate on buildings whether new or old (and your car!) and provide a growing medium for the varieties of moss, lichens and algae that were hardly seen twenty years ago.  Care is needed when deciding how to remove this growth as some chemical treatments and aggressive power washing will be likely to damage your building.

Check for defects such as:

  • Degradation & Delamination
  • Signs of movement
  • Areas of staining
  • Damp patches
  • Mould and algae growth
  • Cracks or erosion