1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Advice and comments on doorway and concrete lintel needed.

Discussion in 'Building' started by adamex, 29 May 2017.

  1. adamex

    adamex

    Joined:
    8 Feb 2015
    Messages:
    21
    Thanks Received:
    0
    Location:
    Manchester
    Country:
    United Kingdom
    Hi all,

    I just completed my doorway extension, original door was 80cm and had 10x6.5 120cm lintel.
    I have made this opening wider 140cm installing 10x10 180cm concrete lintel. Advised by manufacturer this lintel is twice as strong as the old one so in my head seems overkill for the job.

    I would like to ask your opinion on the job before I demolish the rest of the wall.
    DSC06805.JPG DSC06807.JPG DSC06808.JPG DSC06809.JPG DSC06810.JPG DSC06811.JPG DSC06812.JPG
    Thanks
     
  2. Sponsored Links
  3. tony1851

    tony1851

    Joined:
    23 Feb 2012
    Messages:
    9,427
    Thanks Received:
    1,408
    Location:
    Manchester
    Country:
    United Kingdom
    "twice as strong" is meaningless.
     
  4. ^woody^

    ^woody^

    Joined:
    3 Sep 2006
    Messages:
    27,785
    Thanks Received:
    3,490
    Location:
    West Mids
    Country:
    United Kingdom
    Looks like a nice job and should be ok.

    Try not to bash it about too much when you cut the one side for the opening. If you are not sawing, a single sharp tap with the bolster both sides and starting at the bottom to crack it. Then once the blocks are removed, trim by hitting downward at the end of the blocks and not hitting sideways.
     
  5. tony1851

    tony1851

    Joined:
    23 Feb 2012
    Messages:
    9,427
    Thanks Received:
    1,408
    Location:
    Manchester
    Country:
    United Kingdom
    It could collapse at any minute...........
     
  6. tomfe

    tomfe

    Joined:
    27 Aug 2014
    Messages:
    1,262
    Thanks Received:
    160
    Country:
    United Kingdom
    It could turn into a monkey and run around the room.....
     
  7. adamex

    adamex

    Joined:
    8 Feb 2015
    Messages:
    21
    Thanks Received:
    0
    Location:
    Manchester
    Country:
    United Kingdom
    Thank You,

    Here is the lintel I used:
    lintel.jpg

    I have done calculations myself, this lintel can work with loads up to 10 kn/m in my case as opening is 140cm
    This lintel will carry weight from 6x joists (3x going to kitchen and 3 going to living room). Upstairs there is only partition wall and no masonry, + marginal load from the roof. House is modern 15 years old.

    Thank you for the tips with the wall, I was planning to score remaining blocks with diamond blade on both sides or use drill.

    One more question about this lintel, there is no marks on it saying where the top is, does it matter which way it goes? I am planning to ring Naylors tomorrow but maybe you now? Cheers
     
  8. John D v2.0

    John D v2.0

    Joined:
    26 Aug 2016
    Messages:
    6,233
    Thanks Received:
    864
    Country:
    United Kingdom
    For the quoted loadings it needs to have the rebar towards the bottom as that's where the tension is. Steel is good in tension, concrete not so much.
     
  9. ^woody^

    ^woody^

    Joined:
    3 Sep 2006
    Messages:
    27,785
    Thanks Received:
    3,490
    Location:
    West Mids
    Country:
    United Kingdom
    Gone are the days when concrete lintels had "top" stamped in them or were noticeably cambered.

    Nowadays, they all seem to have the steel in the middle, so it does not matter which way up they go. You should be able to see the steel at each end of the lintel, but probably not now! :rolleyes:
     
  10. Sponsored Links
  11. John D v2.0

    John D v2.0

    Joined:
    26 Aug 2016
    Messages:
    6,233
    Thanks Received:
    864
    Country:
    United Kingdom
    Not according to the diagram on the data sheet he posted! Putting the rebar it in the middle would bea bit less useful because that's the dead zone where there's no tension, so it would only really help with the shear.
     
  12. adamex

    adamex

    Joined:
    8 Feb 2015
    Messages:
    21
    Thanks Received:
    0
    Location:
    Manchester
    Country:
    United Kingdom
    Hi, yes I can still see the metal rods, unfortunately I will have to turn it by 90 degree, One side is a bit rough and I think that's the bottom side.

    I have done some more detailed calculation and I question myself now, here it is what I came up with:

    Kitchen: 10m2
    10m2 x (dead + live load) 2.25 KN/M2 = 22.5Kn/m2 There is 10 joist in the ceiling, therefore 20 load bearings
    22.5Kn/m2 Divided by 20 Bearings = 1.125Kn/m2 x 3 Joist above beam = 3.375Kn/m2

    Living Room : 12m2
    12m2 x 2.25 Kn/m2 = 27 Kn/m2 There is 10 joists in the ceiling therefore 20 load bearings
    27 Kn/m2 Divided by 20 Bearings = 1.35Kn/m2 x 3 Joist above beam = 4.05Kn/m2

    So worst case scenario 7.5Kn/m2 is the load of the floor

    That S4 Lintel for 1400 will allow for 10 Kn/m

    There is some weight of partition walls upstairs and probably some weight of ceiling + loft, so not sure if this lintel is up for a job, any thoughts? Thanks
     
  13. ^woody^

    ^woody^

    Joined:
    3 Sep 2006
    Messages:
    27,785
    Thanks Received:
    3,490
    Location:
    West Mids
    Country:
    United Kingdom
    First floor is 2.15 kN/m2 live and dead load

    Clear lintel span is what, 1.5m?

    1.5 x half span of kitchen is .....?
    1.5 x half span of living room is ....?

    to give an UDL of ......kN/m?
     
  14. adamex

    adamex

    Joined:
    8 Feb 2015
    Messages:
    21
    Thanks Received:
    0
    Location:
    Manchester
    Country:
    United Kingdom
    Thanks Woody, sorry I don't follow your way of thinking :)
    the lintel spam is 1400 with 200 resting on each side, not sure what you mean by "half span of kitchen is?" Please explain in more detail and again thank you for your time, I really appreciate this.
     
  15. John D v2.0

    John D v2.0

    Joined:
    26 Aug 2016
    Messages:
    6,233
    Thanks Received:
    864
    Country:
    United Kingdom
    Basically he's saying how to calculate the number of square metres sorted by the beam.
    It's 1.4m the span, multiplied by half the depth of the room above in metres, to get the amount supported.
    Of course any joists, half the weight is supported by each end.
     
  16. ^woody^

    ^woody^

    Joined:
    3 Sep 2006
    Messages:
    27,785
    Thanks Received:
    3,490
    Location:
    West Mids
    Country:
    United Kingdom
    When you calculate loading, the lintel is said to be only supporting half the span of the floor(s) resting on it.

    So you need to work out how much floor the lintel is actually holding up, so its 1.4m x half the span of the kitchen and lounge ceiling joists that rest on it.

    This gives a total loading in m2, and then you convert this to the UDL on the lintel

    The way you worked it out seems to give too large a loading
     
  17. adamex

    adamex

    Joined:
    8 Feb 2015
    Messages:
    21
    Thanks Received:
    0
    Location:
    Manchester
    Country:
    United Kingdom
    Ok this make sense, I thought that full room needs to be calculated and divided by each load bearings anyway this is my situation:

    Kitchen : 1/2 Depth = 1.25 Meters
    Living Room : 1/2 Depth = 2 Meters

    1.4 x 1.25 = 1.75 m2
    1.4 x 2 = 2.8m2

    1.75+2.8= 4.55m2

    2.15 x 4.55 = 9.7 Kn/m2 ???

    Is this right?
     
Sponsored Links
Loading...

Share This Page