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Dangerous discovery? Inadequate support for floor?

Discussion in 'Building' started by piggoy, 24 Feb 2015.

  1. piggoy

    piggoy

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    Hi guys,

    We own a terraced house where the staircase from the ground floor to the basement has been historically moved from the centre to the front of the house. The central wall in the basement has been knocked thru to create an open plan environment and RSJs installed.

    The joists of the ground floor above are supported on the RSJ at one end, but at the other end of the room where the stair case run down it appears that the whole floor is only supported on 5 out of 10 original joists See diagram. None of these joists have been doubled up with "sisters" and there is no additional support provided by vertical posts or load bearing stud around stairs. To make matters worse two of these joists have been notched from underneath for central heating pipes!

    http://media.diynot.com/213000_212570_90495_25237018_thumb.jpg


    I'm no builder or structural engineer but to me this looks very dodgy indeed, although we have lived at the house of 3 years and never noticed sagging or movement, even when we've had parties with many people standing on the floor.

    I intend to get a builder or structural engineer to take a look but I thought I'd share it with the community first. Am I being paranoid? Interestingly there is no record of any building control inspection for this work and it was not revealed/commented by our survey.

    [/img]
     
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  3. piggoy

    piggoy

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    Furthermore the cut joists are only attached to a single piece of perpendicular timber, not a double header. They are also just screwed together, no joist hangers have been used.

    It seems a miracle that this floor is still in place :eek:
     
  4. ree

    ree

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    Given your concerns, perhaps you would post pics of the details you've mentioned above.
     
  5. piggoy

    piggoy

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    Thanks Ree. I'll try to post some pics this evening.
     
  6. theprinceofdarkness

    theprinceofdarkness

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    I would think that two yule posts, floor to ceiling at each end of the cut out and stairs would make a nice strengthening feature.
    Frank
     
  7. tony1851

    tony1851

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    Not Christmas yet, is it? :LOL:
     
  8. piggoy

    piggoy

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    Yule post? Do you mean newel post?
     
  9. piggoy

    piggoy

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    OK, I've uploaded some images. I've picture the left hand side from the perpective of looking at the stairs in the basement.

    You can see that the 5/10 cut joists are simply screwed into a single header which is screwed into the joists at the sides. No hangers, brackets or bolts are used. You can see that the structural integrity of the full length joists is compromised by underside notches and cable channels.

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  11. ree

    ree

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    Thanks for the pics.

    1. The wall string doesn't appear to be fixed to the framing or the wall.

    2. i dont see a single pipe clip.

    3. pipes appear to be in contact with each other.

    4. burnt solder joints. All very amateurish.

    5. Bitumen on the walls indicates past water penetration difficulties.

    Dont go BCO - get a local joiner in. Its a pretty straightforward job to put it all more or less right. At least to make it safe, which its not at the moment. You are right to be concerned.
    Have whoever comes in to look at the trimming joists around this stairwell. And it would be worth having them check the other stairs to the first floor.

    FWIW: ignore user name "theprinceofdarkness" i dont think that he knows what he is talking about.
     
  12. piggoy

    piggoy

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    Thanks Ree. Please could you explain point 1? I agree everything is very amateurish and we seem to be discovering stuff like this all over the house. I fear the past owner was a bit of a cowboy DIY disaster. I won't be getting BCO involved but I will definitely take your advice about a joiner. What about 4x4 vertical posts to provide extra support hidden in a stud wall?
     
  13. ree

    ree

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    The string nearest to the wall doesn't appear to be fixed sideways into the stud framework or the brick wall.

    Dont prescribe for yourself - let a professional do the suggesting from now on.
     
  14. jeds

    jeds

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    Good description!

    Very wise.

    As a minimum you should add joist hangers to the cut joists against the stair trimmer. As you say it's hard to see how that is holding up at all - possibly bolted through from the back side?

    I would also add some bracing to the notches. The vulnerable part is the underside of the joist which is in tension so a reasonable way of dealing with that would be to set a 30mm ms strap into the underside of the joist extending about 600 or700mm either side. Fairly easy to do except you'll have to take a bit more ceiling down to get at it.

    After that it's down to how far you want to go and how much you want to expose. If it were me I'd take the ceiling down and have a good look at the whole lot, but are you up for that sort of work? Bearing in mind you don't know what you are going to find?
     
  15. piggoy

    piggoy

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    Thanks John. The cut joists are connected to the stair trimmer by two screws (at least on the cut joists that I have exposed by the hole I have cut in the ceiling). How large or how deep these screws penetrate into the joist is unknown.

    With regards to strengthening the dangerously notched joists - I was considering bolting 2x4 C16 to the underside with construction adhesive and coach screws. According to the following reference (http://www.diychatroom.com/f5/osb-stronger-than-plywood-23523/) it provides an amazing amount of strength by behaving like an I beam. This part of the ceiling will be inside our new understairs cupboard so it is perfectly fine for the ceiling height to be reduced by the 2x4's. Would it also benefit from adding a 4x4 post within the stud wall of the new cupboard?
     
  16. jeds

    jeds

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    If you can hide a post it certainly wouldn't do any harm. Make sure the post is founded on something solid.
     
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