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Problems with roof structure

Discussion in 'Roofing and Guttering' started by xdrive, 13 Apr 2019.

  1. xdrive

    xdrive

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    Hi.

    I've had a survey done on a 3 bed semi 1930s

    The roof was relaid with concrete tiles about 2&half years ago. Due to this they have produced an extra load. Which has caused "dishing". Also he noted the roof triangulation is not adequate. The ridge and hip tiles need rebedding.

    He has recommended to tie the rafters to ceiling joists to strengthen roof.

    Would anyone know how one would sort out the triangular shape and dishing or can it just be stopped from getting worse?

    I'm concerned the inadequacy in shape may lead to excessive pressure on one wall which may lead to deflection.

    Any ideas on rough cost? Would you renegotiate price?

    Cheers
     
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  3. noseall

    noseall

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    Big lol. Ask him what he means and what is going to stop the ceiling joists from deflecting and the ceilings cracking every time the wind blows.

    Your roof needs strengthening with purlins or deeper rafters etc. You are unlikely to remove the sag unless you remove the tiles and carry out the remedial work with zero weight on the roof.

    Ask the vendors to forfiet £6.5k for starters.
     
  4. tony1851

    tony1851

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    It's unlikely you will be able to remove the 'dishing' as timber tends to take up a permanent deflected shape under long term loading.
    It's possible that either the rafters, or purlins, or both were slightly undersized when built.
    Don't see how 'tying rafters to ceiling joists' will help much, unless the original fixings have failed by rusting.
     
  5. Harry Bloomfield

    Harry Bloomfield

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    No point in bracing roof timbers to the ceiling joists, they are far too weak to help. If the sag is between the eaves and the apex and the apex is straight and level, you could maybe have the roof timber at one side braced against the opposite side - to form an A. Or maybe a reinforcing V sat down from the roof timbers to a structural wall in the middle, if there is one. I doubt anything useful could be done with the weight upon it.

    It is all the roofing companies problem to sort out, rather than your problem. What was on the roof before they used concrete tiles?
     
  6. xdrive

    xdrive

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    not quite sure what roof was before but I've attached a few pics (not great). Can get better ones tomorrow. IMG_20190413_201519.jpg IMG_20190413_202532.jpg IMG_20190413_202221.jpg IMG_20190413_202446.jpg
     
  7. noseall

    noseall

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    Err... has the loft been converted?
     
  8. xdrive

    xdrive

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    No the loft isn't converted.
     
  9. Harry Bloomfield

    Harry Bloomfield

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    There is a Velux.
     
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  11. xdrive

    xdrive

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    Yes however it's not converted.
     
  12. ^woody^

    ^woody^

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    Is the surveyor qualified to actually specify that work? Normally surveyors are not, and should not be making such statements in surveys, as if they are acting outside of their expertise, then that raises questions on the accuracy of their diagnosis and the suitability (and viability) of their suggested action.
     
  13. Notch7

    Notch7

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    Why would a velux be fitted if loft hasnt been converted?

    Is it to give your suitcases a suntan?

    Is there a room of sorts in the loft, even if not officially converted?
     
  14. Harry Bloomfield

    Harry Bloomfield

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    Both halves of the semi seem to have a Velux.
     
  15. xdrive

    xdrive

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    It was a home buyers survey. I know the person does structural surveys and building surveys so would assume it's something he is qualified to say?

    I have done a bit of reading and what he suggested to tie rafters to ceiling joists would be to prevent roof spread which could potentially happen because of the extra load of concrete tiles. But it wouldn't stop further dishing? (Is this right?)

    So would need strengthing with purlins or struts?

    Also am I right in that triangular shape of roof will remain inadequate even after strengthening unless all tiles are removed and remedial work carried out. ( Sounds expensive)

    I'm guessing both roofs were done at same time and velux was added for light or maybe future plan to use as store or convert. Currently no room or boarding. Can see joists, rafters, etc.

    I'll try to get better pics of roof tomorrow.
     
  16. Notch7

    Notch7

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    Yes, I thought thst.

    Weird
     
  17. Don't see how anybody on here can guess what needs doing without knowing the details of the roof construction . Only a proper 'structural ' survey and report would tell you what needs doing to make the roof structurally stable.
     
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