correctly installing lintel?

Discussion in 'Builders' Talk' started by legepe, Nov 9, 2018 at 5:16 PM.

  1. legepe

    legepe Member

    Hi all
    I want to place a 210 x 100 x 1800 concrete lintel above fire place, only 100mm will actually sit inside the wall the the rest will be on the outside creating a mantel piece
    My query is should this lintel only be installed with the high side (210mm) sitting vertically? or am I wrong thinking this?
    Can anyone advise
    Thanks
    legepe
     
  2. sospan

    sospan Well-Known Member

    With most chimneys the bulk of the weight is supported by the cheeks of the fireplace and it is then "corbeled" as the height rises. The front of the fireplace, is normally a single skin for the first 8 feet and then is tied in and gets thicker as it rises.

    Normally a 100mm wide lintel is good enough to support the face of the chimney breast but it depends on the construction and the strength of the sides. The strongest dimension would be with 210 vertical.

    Of the ones I have done recently, I have done two methods - one with a face screwed onto the lintel and then with a top fixed at 90 degrees and corbels to hide the screws. The other style was just a rustic beam which had keyhole brackets on the back which just slotted over screws in the lintel
     
  3. legepe

    legepe Member

    Thanks sospan
    I would really like to post some pictures but this site will not allow it..! it just keeps telling me theyre too large?
    I completed about 6 months ago a different fireplace in an old terraced house using the method that I want to do again with this one. that one hasnt fallen down but I was unaware then that the lintel was supposed to go in sitting upright.
    I didn't have to touch any of the corbles in the terraced house because the original builders opening was big enough, however with this one the property was build tin 1968 and the corbles are much lower down so for me to make sufficient opening i will have to break/remove the corbles and like youve already pointed out they are load bearing.
    How do I get around this?
    legepe
     
  4. dobbie

    dobbie Well-Known Member

    The lintel is not supposed to go in upright and is not designed for that.That is bad advice you have been given.

    The lintel would have been designed to lie flat and have the stress calculated to be installed that way.
     
  5. sospan

    sospan Well-Known Member

    Most of the fireplaces, I work on are made out of stone, so you can never tell how strong the wall is. I tend to brace the alcoves and then put in a acrow props with a strongboy head quite often this is just belt and braces.

    If you each end of the lintel, removing stonework towards the centre, you will see how it is supported, quite often the bricks or stones will be at 90 degrees to the ones removed and will support the ones above.
     
  6. sospan

    sospan Well-Known Member

    There are no calcs, it is an off the peg lintel.
     
  7. dobbie

    dobbie Well-Known Member

    Which the lintel in question is designed to be installed flat,not upright.
     
  8. Richard_

    Richard_ Active Member

    Incorrect.

    Many standard concrete lintels have a single prestressed bar in the centre. The bar is in the centre to enable the lintel to work upright or on its side. Upright would be stronger but horizontal would be strong enough for this application.

    Other lintels have bars in the bottom, they can only be used in the orientation with the bars at the bottom.
     
    Last edited: Nov 10, 2018 at 8:55 PM
  9. stuart44

    stuart44 Active Member

    Composite concrete lintels have the bar in the centre, as the 3 courses of brickwork above form part of the lintel. The rough concrete should really go at the top to form a key for the brickwork.
    Non composite lintels that can directly take a point loading will have steel at the bottom and maybe the top as well.
     
    Richard_ likes this.
  10. Richard_

    Richard_ Active Member

    Not forgetting to prop lintels over 1200 long until the mortar had cured.
     

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