The first symptoms of defective concrete blocks in your home may be cracking on the surface of external walls. You could easily mistake this for normal settlement cracks or defects in the external plastering. The cracks generally start to show on the surface 6 to7 years after construction.

Tell-tale signs  defective concrete blocks:

• Horizontal, vertical and sporadic cracks on the external leaf of the external walls with no correlating cracks internally.
• Vertical cracks at corners approximately 200mm offset and parallel to the corner. These cracks tend to extend from ground to roof eaves level.
• Blockwork displacement with gaps appearing around window and external door openings.
• The elevations facing the prevailing winds are worst affected.
• Evidence of moisture ingress in extreme cases.

Upon detailed physical examination the concrete blocks are found to be open textured, porous and easily broken with basic hand tools and little external force – not how you expect a concrete block to react! Laboratory testing has found low cement content, a high water cement ratio, low compressive strength and an abundance of muscovite mica.

The pace of deterioration depends mainly on how defective the blocks are and the quantity affected. Adverse weather conditions are a contributing factor.

How many homes are affected by defective concrete blocks?

I have inspected over 220 houses in the past two years, but the number of houses affected is estimated to be in the thousands.The current controversy surrounds defective precast concrete blocks used in the construction of buildings in Donegal, mainly in the north east of the county, extending to and including Letterkenny and Inishowen. 

Needless to say, it’s a nightmare for homeowners who are facing:

• Huge costs associated with remedial works.
• Diminished market value consequent to the defect.
• Difficulties in renewing home insurance on their property.
• Getting certification from Engineers on partial remedial works.
• Limited redress options as some have purchased their home from a Developer who is no longer in business or previous homeowner with no traceability or proof of which company supplied the materials.

If you have any questions about defective concrete blocks, seeking redress or other building defects, then please call us on +353 74 9129243 or email damien@consultingengineers.ieVIDEO: Defective Concrete Blocks