4 reasons why a building may experience relative movements.

Hardly anything can shake your confidence in a building more than cracks on its wall or floor .This is taken to be the  smoking gun evidence of deployment of substandard   building materials   and poor workmanship, which can sent the value of the house into a tail spin. However these cracks can also be caused directly by a building’s relative movement either partially or as a whole. Which in turn has nothing to do with quality of building materials deployed but everything to do with lack of great workmanship.  Parts of building or the whole building structure will experience unwanted movements because of either one of the following phenomena: settlement, changes in temperature, variation in moisture levels, wear and tear or building loading.Embed from Getty Images

Settlement.

The settlement and uplift   all buildings experience is the result of building’s load on the foundation. Settlement is slow and act in one direction causing a shearing effect on sealants like mortar and mastic used in joints. If this shearing is great, it may lead to structural cracks which obviously is not sweet music to ears of those who have invested in it for the long haul and are not ready to deal   with recommendations of the   county and national building authorities.

Also settlement can be caused by dynamic forces like earthquakes and explosions.

Temperature changes.

Temperature variation within a day and   between seasons can cause a building’s various parts to expand and contract. The amount of these contraction depend on the materials used. Timber has the least movements with any drop or increase in temperature. Glass, steel, bricks, stones and concrete have moderate reaction to changes in heat in the atmosphere. Last but not least, plastics and Aluminium exhibits astonishing expansion or contraction when it becomes hot or cold.

Again consider before-hand  using  dark  colours  , good insulation   and  thick  construction materials on your building ;they  respond  better  when the weather  changes from  cold to hot or the reverse. Which of course means, minor movements in the building parts.

Moisture Changes.                                                                

Regardless  of the weather  conditions, concrete and mortar  will  show  initial contraction  when it cures, timber  will show  little shrinkage if properly seasoned  and  bricks  will expand  if used  immediately after  firing. Depending    upon the atmospheric fundamentals, moisture and heat related movements may resist or complement each other.

Moisture exposure in building is mainly due to wall penetrating rain water, damp soil, high water table, pipe leaks inside the wall, and open water in the event of high flooding.

This  moisture   is likely  to  cause deterioration on the  building  interior finish and  pre-mature aging  of  wooden  parts  because  of the attack of mould and  fungi. Also  moisture  is  likely  to cause  corrosion and  rust on metal parts  like windows  and the roofs.

By the  same  breath, deterioration of materials such as  corrosion  of steel  or  sulphate  attack  on concrete is often  associated  with irreversible  expansion causing  movement  of  adjacent  components. Again concrete  structures may  exhibit  creep  which is  a  gradual  permanent   deformation  under load over  many  years.

Building loading

Dead weight is responsible for initial building settlement. However  movement  associated  with live loads  like  Cars, human traffic  and  wind   can  cause  perpetual cyclical  movements within a building components.

 

©2017Copyright: East Africa Little Hardware Ltd.

Sources: 1.Materials for Architects and Builders by Arthur Lyons

  1. http://www.sika-africa.com
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