Cause

• Buildings rely on solid foundations to maintain their structural strength. The natural movement of the ground due to moisture retention in the fall and winter and drying out of earth in the summer will cause some cracks in foundations. Trees can do more damage and create larger, structural cracks or gaps when the tree roots grow up against or into the concrete or masonry foundations.
  
  

Damage

• Most tree root damage to foundations occurs when the tree root grows too close to the masonry or concrete, sucking moisture from the surrounding soil and shrinking it. This action creates gaps and destabilizes the soil around the foundation structure. The foundations move with the shrinking soil and the movement forms cracks.
  
  

Repair

• The sudden appearance of cracks in the basement or elsewhere in the house might indicate a problem with roots from nearby trees. The only way to solve the problem is to dig a trench around the house to the depth of about one foot deeper than the foundation and remove any encroaching tree roots. You will need to have the trees responsible for the damage felled. Most people hire structural engineers to carry out this work, repair foundation cracks and fill the trench with a solid tree root barricade that prevents roots from reaching the foundation.
  
  

Prevention

• The most effective way to avoid tree-related foundation cracks is to plant new trees well away from buildings. The extent of a tree's underground root system usually exceeds the size of the tree's canopy. Find out how large the tree and its root system will grow before planting it and then plant the tree a sufficient distance from the nearest building.