Risk Management > Causes of Deterioration

Diagnosis and Prognosis

The underlying cause(s) of every conservation issue, problem, deficiency and building pathology must be identified, monitored, assessed, and eliminated and/or corrected before the resulting condition caused by the problem(s) are treated.

Examining a house involves some of the same techniques that doctors use on a sick person. A doctor reviews medical records and asks a patient to describe any troubling symptoms. Analysis includes visually inspecting the patient, a physical examination, and, possibly, testing to identify signs of disease.

A diagnosis is developed based on these symptoms and signs, the results of reliable tests, and the doctor's expertise and experience with similar conditions. Possibly, the diagnosis will identify the underlying causes: the disease itself. Then, a prognosis will predict the expected course and complications of the disease if left alone; or the outcome, if treatment occurs. A treatment will be suggested to the patient for consideration. If undertaken, the treatment will hopefully relieve the symptoms while curing the disease. Preventive measures will be prescribed to keep the disease from recurring.

Cause and Effect

A patient may have the flu. The symptoms may include a high temperature, a cold, aches and pains. The cause is likely a bacterial or viral infection. A doctor can prescribe medicine to relieve the uncomfortable symptoms, but this will not get rid of the flue. It is only once the underlying cause is cured — by either medication or by the patient's immune system — that the disease will go away. A vaccination or medication may prevent an illness from recurring.

This example shows the importance of careful diagnosis and treatment. It also explains that the cause must be treated to cure the patient:; simply reviewing the symptoms will not work. This analogy can be used for buildings just as well, with one important difference: a body can heal itself. Buildings cannot. They need the help of owners, craftspeople, and other professionals to remove the causes of deterioration through careful preservation work.

It is unlikely that all the problems and causes will be discovered during an initial building inspection. This may require detailed assessment, followed by more analysis, testing and monitoring -- over time, and under various weather conditions.

 It is very important to understand the difference between recording the symptoms of a problem and figuring out its underlying cause. There are usually several causes, each serving to complicate a particular problem. A correct preservation plan can be developed only once each cause is discovered, analyzed and understood.

Intrinsic Causes

Faulty Materials

  • defective products
  • variations in products, quality control

Design and Construction Defects

  • errors in design, style
  • undersizing, poor connections
  • poor construction methods
  • faulty workmanship
  • incompatible components
  • location of structure (micro environment)
  • geo-topographical location (site; macro environment)
  • site orientation of structure
  • subsurface conditions

Extrinsic Causes

Physical Factors

  • moisture (ground water, rain, snow, floods, storms)
  • temperature (expansion / contraction, freeze / thaw)
  • motion (gravity: settlement, ground subsistence, earthquakes)
  • abrasion (wind, mechanical wear)

Chemical and Electro-Chemical Factors

  • ionic solution, galvanic corrosion
  • alteration and replacement

Biological Activity

  • lichens and plants
  • rot and xylophagous insects

Human Action

  • neglect, lack of maintenance
  • war
  • theft, vandalism, arson
  • accidents (fires, leaks, floods, explosions)
  • pollution, acid rain
  • change in site/design
  • destructive alterations
  • inappropriate treatments
  • poor "preservation" practices
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