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RSJ - 203mm (8inch) RSJ sitting on original 4inch wall

Discussion in 'Building' started by dbtrenovations, 28 Jan 2014.

  1. dbtrenovations

    dbtrenovations

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    Hi, hope someone can help me!!! urgently ;)

    Long story but I have been working on a house refurb for over a year as my business partner turned out to be a con man and basically destroyed a house. Long story, but basically I have been working free of charge for 6 months correcting serious issues and starting over again with the work.

    My latest discovery I need some advice on.

    The integral garage was converted to livable space. In doing so a steel was inserted across a load bearing wall to open the kitchen up.

    This is the problem. The steel was massive at 203mm x 203 mm and approx 20 foot long.

    On on end it is supported on a 440 x 220 padstone - all correct and good

    The other end is sitting on top of the existing 4inch wall with foundation. Another wall made from thermalite block, tied to the existing brickwork, and was built off the existing 6 inch concrete that was the garage floor.?????

    Now as i see it the steel is half sitting on a solid load bearing wall and the other half on the breeze block wall. My concern is the weight is equal on both existing brick work and thermalite wall, and this means the existing 6 inch slab isn't man enough?

    A basic drawing is attached showing the end view so you can see the walls and layout.

    If that makes sense can anyone advise???
     
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  3. pinenot

    pinenot

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    Hello there, very nice to see a man with morals and a willingness to put right. Hopefully you have the original receipts and can verify the newton rating of these Thermolite/Aerolite blocks, as some are indeed load bearing, by my guess you are looking at a 3.6 N/kg block, because at least half the load is on the concrete block wall etc. Thermolite are normally sold as 3.6 N/kg so no problem there.
    The six in concrete garage floor, you would have to guess at it's C rating, if for instance it's C 30 then I would say it has all the strength ness., but if your still worried by cutting out/core drilling a large enough access through the concrete floor at both ends of the load bearing walls i.e. under the padstone locations and continue an excavation as far as you deem suitable, then pour in some C30 or even C45 concrete to beef up that section of concrete, all should be well. A couple of props on 1 metre timber spreader footings should take care of the load meantime...hopefully that will help...pinenot :)
     
  4. Static

    Static

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    Maybe its me but i found the above reply confusing and potentially miss leading..
    If the construction of the wall and slab is as you show then assuming there are no wall ties between the two skins, the block side will settle and then original will take all of the load (if not an eccentric loading)..

    If this is not built to your building regs plans then either contact them for an inspection or get a structural engineer out to give you remedial options.
     
  5. pinenot

    pinenot

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    Which part did you not understand, the Newton resistance associated with building materials/blocks, the under pinning of the (load bearing aerated block wall ends with a substantial load bearing capacity, or is there something else. If I've missed something, please explain, I do agree an S/E's rubber stamp on these issues would be welcome but not essential.

    Just to clarify my position - It's my opinion that, I don't think the O.P. needs to worry about the load bearing capacity of Thermoblocks (if the original invoices/delivery notes are available to qualify the weight bearing (N/kg) properties of the blocks used, all to the better). However, Thermoblocks were/are sold in various load bearing capacity and as far as I know never less than 3.6 N/kg2 I've not come upon any Thermoblock walls that have settled disproportionately to their un aerated counterparts, but stand to be corrected. As a conscientious working builder what's, dbtrenovations, your opinion? ...pinenot :)
     
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  7. Static

    Static

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    Well first off its N/mm2.. Thermalite turbo blocks are 2.9N/mm2, only the Thermalite shield blocks are 3.6 the rest vary upto 10N..

    Personally i do not know what load the beam is carrying so would be unable to comment on the suitability of the blocks, irrelevant of their strength..

    What was asked was about the garage floor slab taking the loading.. which is where the settlement may occur.. Just adding some extra concrete on top of some adjacent foundations is not underpinning..
    If this is really an issue, the best solution would be a new engineering brick pier at the end of the wall (so under the beam end) and new foundations under that pier..
     
  8. pinenot

    pinenot

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    Not hat I want to an online argument, but I answered to Thormoblocks not Thermalight blocks. But on the subject of the later here's your starter for ten ;) - https://environment7.uwe.ac.uk/resources/constructionsample/Conweb/walls/blocks/print.htm ..I'm pleased you came back at me on that, as a good debate should bring about a good answer for the O/P, I must admit I am probably leaning towards his situation, rather than the correct procedure though.
    On the under slinging/pouring concrete at the floor slab where it's carrying the load (as per you don't know how much the load is) this I've done before when in charge of sites (all with engineers approval) and have used this to good effect on retaining walls, suspect foundation edges and a host of other situations where digging up to put in a square sided pad like affair was uneconomical, both financially and timelessly. What' wrong a sprawled mass of concrete v a prissy block, surely it's the mass that counts...pinenot :)
     
  9. dbtrenovations

    dbtrenovations

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    Hi, thanks for the replies both Pinenot and Static. I really appreciate your time to reply and find the points raised very interesting.

    My initial thought was 'ffs this is gonna be a real pain' the wall is built, plastered etc. The garage floor although no big deal has been liquid DPM'd and to top it off the floating floor installed, including 100mm Xtratherm/Kingspan. Ok this is no big deal to remove, but with time being precious was hoping i could get around knocking down the wall (or at least part of it) removing all 6 x 2 joists etc, cracking the floor, digging a footing and rebuilding an engineering block pier.

    My first step was to dig an inspection hole through the original garage floor to determine the depth of slab, foundation of existing wall behind and decide whether i could indeed just dig down and under sling to support the block work.

    The blocks are double shields so assume 3.6N or above.

    I was surprised at the 150mm depth of the slab even though it is of course towards the edge. I was expecting 100mm. Which led me to question whether its adequate to just leave?

    The steel actually sits on these 2 skins by almost a metre with 2x 440x215 padstones on each skin

    My opinion is shields, tied to existing wall with a 150mm slab should be adequate. BUT fear the correct thing to do is remove and rebuild a pier with a correct footing and BC approval/sign off.

    Thanks once again to the pair of you and please feel free to reply as Im starting to lose the will to live on this job, but at least i can sleep at night.
     
  10. Static

    Static

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    Doesn't sound, least the walls are tied together..

    Still you should get confirmation from your SE, your paying for his insurance and advice you may as well get full use of his services.
     
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