Issue with face blocks

Discussion in 'Builders' Talk' started by Ian Hunt, Jul 13, 2019.

  1. Ian Hunt

    Ian Hunt New Member

    New extension to bungalow 7.5m x6 m and new double garage 6mx6m. Issue is that some of the face blocks are cracking in the middle on both builds and some cement lines have come away from the edges. It's like the blocks have shrunk. The 7.5m gable does not have an issue used blocks from old garage after cleaning them up as gable not seen from road.
    Only new blocks have this issue.
    Any ideas? The blocks were purchased from a well known merchant.
     
  2. blarblarblarblar

    blarblarblarblar Active Member

    Split blocks and broken mortar joints, possible movement, but sounds like mortar is too strong. Pretty sure, someone will correct or add to this.
     
  3. stuart44

    stuart44 Active Member

    Generally concrete blocks are at their largest when laid and will shrink, whereas clay bricks are usually at their smallest when laid and will expand.
     
  4. Ian Hunt

    Ian Hunt New Member

    Building only 4 months, no movement below dpc. Mix 5-1
     
  5. Ian Hunt

    Ian Hunt New Member

    Does this mean blocks were too green?
     
  6. stuart44

    stuart44 Active Member

    Could be. The mortar mix shouldn't be too strong either. On long runs movement joints are needed. Reinforcing the beds joints can also help.
     
  7. xednim

    xednim Active Member

    faulty batch of blocks? not well compressed on production line?
     
  8. Ian Hunt

    Ian Hunt New Member

    They have offered to pay for cut out and replace as good will jesture but don't accept that blocks were faulty. I'm just worried for the future. It's funny none of the older blocks from the old garage that were cleaned up have broke
     
  9. xednim

    xednim Active Member

    so they have been aware that something could be wrong with their material, possibly they had more complains than only yours
     
  10. Ian Hunt

    Ian Hunt New Member

    I did ask, they said no. How do I prove a fault with the block?
     
  11. stuart44

    stuart44 Active Member

    It's not an uncommon problem with blockwork when they are a bit green, as they shrink a bit when they dry out.
     
  12. sospan

    sospan Well-Known Member

    Single or double skn

    You say "face blocks" are they cracking on an inner skin or outer as some fair face blocks are only designed for internal use
     
  13. blarblarblarblar

    blarblarblarblar Active Member

    Never heard of concrete blocks being ‘Green’, do you mean too fresh, too new?
     
  14. sospan

    sospan Well-Known Member

  15. Ian Hunt

    Ian Hunt New Member

    Of course the issue is when do they stop shrinking? If I get the blocks replaced they will call it job done. What will I find after winter? I think I need an expert who can write a report to cover me for the future?
     

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