Steel Lintel or Concrete?

Discussion in 'Engineers' Talk' started by Alec_Ch, Sep 17, 2018.

  1. Alec_Ch

    Alec_Ch New Member

    Hello, I would like to demolish part of load bearing wall to have open kitchen and living space. There is an existing door on the wall and the new opening would be about 2.6m

    I think we need a lintel for supporting upper floor structure (mid terrace house small house). This could be a RSJ steel lintel or concrete lintel. Anyone could help to explain their advantages and dis vantages.

    I also see on some lintel' manufacture website, they could also do simple structural calculation to identify the size of lintel. Is it sufficient for building control?

    Many thanks.
     
  2. KIAB

    KIAB Well-Known Member

    RSJ every time for that span, & you need proper calculations done, & not worked out on the reverse of a f ag packet.
     
    Last edited: Sep 17, 2018
  3. Dam0n

    Dam0n Active Member

    For a 2.6m span you'll need a steel for sure.

    As to what steel, I'd be getting a structural engineer to spec it for you. Don't just stick any old thing up.
     
  4. Alec_Ch

    Alec_Ch New Member

    Thank you for your feedback

    I believe that I do need 2 padstone on both edge of steelworks. I can see some calculator online to identify the size of beam. Could I trust it?

    be most grateful if someone could help. I have done the plan by myself.
     
  5. KIAB

    KIAB Well-Known Member

    The rsj needs a minimum of 150mm bearing each end on concrete padstones.

    Ideally need proper calculations done.
     
  6. sospan

    sospan Well-Known Member

    You have to engage with your local building control office to get permission to undertake the work. They will require some calculations from a structural engineer to accept an RSJ. There are a lot of things to consider alongside putting in pad stones. The BCO/ SE/ Architect will advise you
     
  7. Jord86

    Jord86 Well-Known Member

    This post surely must be a wind up.
     
  8. sospan

    sospan Well-Known Member

    beginning to think there are few on here tonight - narrowing windows on a bungalow is another one
     
  9. Richard_

    Richard_ Active Member

    Talking of building control, I have just finished an identical job. I'm a structural engineer used to rather large projects with complex analysis so I threw myself into inordinate calculations, about 10 pages for one beam *&*%& ! Mind you its been 20 years since I've done the calcs by hand so I was starting from first principles, also it was for timber and EC5 is a total pain for hand calcs.

    Anyway, I happen to have a rather hefty glulam beam at home so I decided to use that. It was oversized something like 600x200 and I needed 250 x 150. I cut down the depth and lost the will to reduce the width.

    So building control pop round and I'm about to regale my battles with EC5 and it's unending modification factors. I also know the pedigree of the timber as it came from a site I was working on a few years ago. Polish larch as it happens, a fine material and so much better than UK larch. Planted in the mid-1920's so roughly the same age as the house, there's serendipity for you. Imagine what that tree must have witnessed from WW2 to the cold war, and to come to such an non-descript end propping up a bathroom floor in the UK.

    Knock on the door, chap flashes an ID card "building control, you've got a beam in the kitchen?" and charges though before I can say a word. He says "I've never seen that before ... I'll email the certificate"

    "What about the calcs?"

    "No need, that's not going anywhere"

    Door slams behind him, certificate appears in my email 2 mins later.

    The moral of the story is to install a whopping glulam beam.

    ....

    (Please don't take that as my professional advice)
     
    Dam0n and Jord86 like this.
  10. Alec_Ch

    Alec_Ch New Member

    That sounds a little bit complex to me. If I just additional door in load bearing wall, do I still need to specify RSJ and notify Building control?
     
  11. sospan

    sospan Well-Known Member

    If you are widening an opening in a load bearing wall Yes. Really if it sounds complex you shouldn't be doing things with load bearing walls. Even very experienced people can get things wrong with load bearing walls
     
    KIAB likes this.
  12. Greentram

    Greentram New Member

    Just to add to the above, it's not just a question of the beam being strong enough, but ensuring that the brickwork supporting the beam is adequate. Definitely needs an engineer's appraisal.
     
  13. Richard_

    Richard_ Active Member

    Yes, because gravity.
     
    Jord86 likes this.
  14. Richard_

    Richard_ Active Member

    Sorry, my reply was facetious.

    You're asking "how long is a piece of string". If you were putting in a single door then a normal lintel would normally be OK ... as long as there are no unusual concentrated loads from above such as post or column above, or a trimmer beam. If you are demolishing an entire wall then a steel beam (or glulam if you have one ;) ) would be needed ... or perhaps not if it is a partition (ie non load bearing depending on what is above).

    So the answer ranges from needing a steel beam for a single door, to nothing for taking down a wall, and everything in between.

    This can be rather dangerous if you get it wrong so there is a requirement to contact building control to demonstrate you have taken reasonable measures (ie calculations where needed). Note BC only verify that you have demonstrated that you have taken reasonable measures (incl. calcs as required) what you have done. This is an important legal point, the legal liability remains with you, they won't do the calcs for you.

    Contacting BC isn't complex, it's a 5 min form and a 5 min site visit.
     
  15. Dam0n

    Dam0n Active Member

    You can also get the beam calcs done by online by structural engineers without a site visit. I've used them before and although I fell out with them for being monkeys and not providing what I'd asked for I'm sure they would be fine for simple projects.

    Bco approved docs supplied!
     

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