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Best way to repair this?

Discussion in 'Building' started by Cgas, 10 Jan 2016.

  1. Cgas

    Cgas

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    Afternoon,
    Attached are some pics of a crack that was around when we bought the house (gotten no worse) just getting finished inside so moving onto outside during summer, so what's the best repair for this crack is it best to just remove and replace cracked bricks and repoint or can them Hellifix steel bars be used on verticals ? We had a structural survey before purchasing on the specific crack to which the engineer said it's point load something to do with the outhouse falling away and possibly some thermal movement. The flat roof that is visible is coming down and the outhouse also. Nothing on the internal walls behind the plaster or in the loft space. Just curious to know if it is thermal will this carry on happening even when repaired ? & best way to repair?
    TIA.
    image.jpg image.jpg image.jpg image.jpg
     
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  3. KenGMac

    KenGMac

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    Cgas, Hi.

    OK the position of the crack is consistent with the position of a thermal crack, but? the width of the crack appears over large for something that has been called thermal?

    As a rule of thumb, Expansion joints should be built in during the construction phase at about 6.m. centres if the main wall to the elevation is more than 6.m then there is a high probability of thermal action.

    I think the Cavity has been "insulated" by being filled?

    There would appear to be no lintel above the old 1960s ? door in the main property wall, the brickwork above the door appears to be resting on the timber of the door frame? never a good idea? however Helibar can address this issue, I note you appear to have researched this option which is a seriously first class repair method where there is no lintel installed, however, the overall crack width worries me? it is wider than I would expect to see?

    In your final attached image there appears to be a considerable gap at the base of the brickwork, it appears to be somewhere between 15.mm. to 25.mm wide at its nearest point to the main property wall, but the gap reduces to 0 at the furthest extremity of the extension away from the property? as an aside. what is the long length of material which is supporting the extensions brickwork? is it the floor slab, or is it a lintel built in there but for what reason? it is a bit puzzling? Did your Engineers report mention this? if so what was his opinion?

    What age is the property and have you any idea when the extension was added?

    As for a repair to the cracked brick? you will not get a colour match for the brick, if you simply point the crack, any future valuation surveyor will scream SUBSIDENCE ant that isn't good on any survey report???

    How reliable in your opinion was the Structural Engineer? and his report???

    Ken.
     
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  4. Cgas

    Cgas

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    Hi appreciate the reply, the house is around late 1960s.

    We actually had 2 people look over it one was a paid for structural engineer at cost of the seller of the property (chosen by them) the other was a friend of a friend who had a look purely for advice and nothing written however have since moved away hence why I can't ask him to look again. So I'd hope fairly reliable.

    Unsure of what you mean by expansion joints can you explain?

    The windows and doors are next on the list, all to be changed in due course so will look into getting lintels etc sorted, hopefully.

    The outhouse is a mystery to us also, it was a boiler house but I've moved it out of there and into main house as I wanted to get rid of the outhouse as its taking up space and no use for anything, so my plan was to use the bricks from the outhouse and remove the old cracked bricks from the crack and replace as necessary. As for the material holding the outhouse up yes it's a steel lintel and actually it's probably a good few inches by the main wall to the house.

    The house is actually built into a bank so the pictures you can see of the side door are actually the second floor. If you go round to the other side of the house it's a full 2 storey. You can actually go under where the door is into a void in the floor.
     
  5. tony1851

    tony1851

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    We can't see the whole picture, but I doubt that crack would be caused by a 'point load', and is certainly not thermal.

    Maybe movement due to the house being built into a bank?.
     
  6. Cgas

    Cgas

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    In regards to how the house is built and what I mean it's built into the bank is best shown in this picture. The outhouse can be seen between the shed and the left hand side corner of the house. The house next up is obviously the one showing above the shed as you can see its quite a lot higher just shows the gradient of the bank. Ignore the building site that is our garden at the minute.
    image.jpg
     
  7. Cgas

    Cgas

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    Is movement more so cos its built into a bank? Is that usually the case?
     
  8. ^woody^

    ^woody^

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    Movement would be internal too, but its not indicative of a movement crack. And its certainly nothing to do with a point load

    That's a classic thermal crack, in the weakest part of the wall due to the mass of the outhouse and the gable panel shrinking.

    The best option would be form a vertical expansion joint rather than try and repair it and risk it occurring again.
     
  9. Cgas

    Cgas

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    As always appreciate the advice woody! Just to make sure is this what you mean?

    Cos when googled it come up with all sorts of horrendous ideas such as this below!
    image.jpg

    Will have a good look into it over next couple of weeks until the weather picks up, am I best off getting the outhouse down and door/lintel done before I even bother sorting this out?
     
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  11. ^woody^

    ^woody^

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    For a proper job, you will need to form a nice vertical joint and make some of those cracked bricks into half bricks.

    You will need to insert some sleeved ties - to tie the panels and allow movement. Every 3 or 4 course
     
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  12. CambridgeBrummie

    CambridgeBrummie

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    Are those calcium silicate bricks?
     
  13. Cgas

    Cgas

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    Any idea how to find out? Wasn't noted on the homebuyers report or the structural survey by the engineer or mentioned by the friend verbally so I doubt it unless they didn't notice or thought I knew ??
     
  14. ^woody^

    ^woody^

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    You can see that they are not calcium silicate.
     
  15. wessex101

    wessex101

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    I was thinking the same thing. From the photo they look like they could well be a calcium silicate or sand lime brick and the vertical crack is a classic shrinkage crack. The smooth looking face and very crisp regular edges, if you can cut one or the crack is wide enough they should have a very sandy texture inside. There used to be a brick works near me that turned out a brick very similar to that, horrible things that would produce identical cracking.

    Remedy is to cut in a new vertical joint with remedial cavity wall ties both sides and slip ties across the joint.
     
  16. Cgas

    Cgas

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    From this description I very much doubt it! The bricks are far from a smooth face (assuming you mean similar to an engineering brick face is what I'm comparing against) and as for the inside of the brick they are literally horrendous strength wise to work with, try to put a core through for boiler flue and extractor was horrific and the less holes I have to create the better and the comparison I've got is that I drill quite a few cores throughout the year installing boilers. Hope this helps!
     
  17. wessex101

    wessex101

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    I can only go on what I have seen before, I understand some can have quite a rough face and be almost indistinguishable from clay bricks.

    The strength of the brick sounds about right. They are effectively a pressed concrete brick (without the coarse aggregate) and as with concrete gain strength as they get older and again as with concrete shrink in size, hence the shrinkage cracks.

    Of course I am probably barking up the wrong tree but it was the first thing I thought when I saw the photos.
     
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