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Some lintel advice needed for an admirer and a newbie

Discussion in 'Building' started by gasgas249uk, 10 Aug 2010.

  1. gasgas249uk

    gasgas249uk

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    This is my first post so please be gentle with me. Ive done some searches but cant find the advice i need ...so here goes .

    Clay tiled roof - custom roof being cut in in 2 weeks so im preparing.

    Ive been building this single storey extention.It has a hipped roof over the main section and a flat roof over the hall nearest me(when i took the photo)

    As you an see on the main room the right hand corner is rounded. The hip comes down on this side and has nowhere to rest. The architect has come up with a 3 section wooden lintel (supported by mullions)above the curved window to the right of the pillar(chippies are sorting this)
    To the left of the pillar a also need to support the hip at plate level. The span is 2750mm.

    My questions are.

    1--Do i need a 4x2" plate on top of the wooden lintel or will the lintel do?
    2--Whats code of the box lintel to use on the 2750 span?
    3-- On this 2750 span will it need a 4x2" plate on top and if so how do i attach it to the box lintel (mortar? )please?

    Thank you for your help with this. Im working on this night an day in between work and some things im working out , but this i need help with.
    Thanks again.

    Cheers
     
  2. JoeMar

    JoeMar

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    surely this is one for your structural engineer to answer.
     
  3. jeds

    jeds

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    1--Do i need a 4x2" plate on top of the wooden lintel or will the lintel do?

    Fit one if you need to adjust levels otherwise not.

    2--Whats code of the box lintel to use on the 2750 span?

    There are so many to choose from. Try the Catnic lintel selector (Google)and choose one that best does the job. If it is taking roof load only the working load will about 2.5kN for every metre of roof span/2. If your span is 4m then it will be 4x2.5/2=5kN/m. If the span is 2.7 then the total working load is 2.7x5=13.5kN.

    3-- On this 2750 span will it need a 4x2" plate on top and if so how do i attach it to the box lintel (mortar? )please?

    Mortar bed.
     
  4. gasgas249uk

    gasgas249uk

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    Jeds,

    Thats for the reply.

    I used the catnic product delector and it came up with found a box lintel ----http://www.catnic.com/lintels/CN55A.aspx

    Ive got cavity walls so this must sit on top of the inner skin???

    They only supply these up to 2700 !!
     
  5. Static

    Static

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    Try phoning them..
     
  6. gasgas249uk

    gasgas249uk

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    No , they dont do any eaves lintels over 2700. Why do these lintels have a 75 flap sticking out on them?

    Ill have to get the Architect to give me some guidence. Trouble is ----hes not the easiest to get in touch with.
     
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  8. Static

    Static

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    Well then its a steel beam..
     
  9. jeds

    jeds

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    Unless I'm missing something I can't see why you wouldn't use a standard open back cavity lintel? CG 70/100 (or other depending on your cavity width)
     
  10. theoldun

    theoldun

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    You have got the wrong lintel You want a heavy duty box CN6XC or CN66XC. Page 42. They go up to 4800 long.
    Muck bed, when hard fix plate with 1mmx20mm pre holed galvanised strap banding. Nail on to plate, wrap round lintel and nail back on to plate.
    Blockwork is a credit to who ever rattled it up.
    oldun ;)
     
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  11. Static

    Static

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    Eaves lintels are deliberately shallow to avoid clashes with the rafters.. if there is no depth issues then a deeper box lintel would be sufficient.. as stated above..
    But normally with no depth issues you then provide external brickwork, so need a tophat lintel.. work out your makeup of wall above the lintel and height restrictions..

    CN6XC and CN66XC are both 219mm high..
     
  12. theoldun

    theoldun

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    Closed eaves lintels, whether they be open back with a 60mm front flange or box with a 75mm front flange, are only manufactured up to a length of 2700.
    Over this length you have to tackle the problem a different way. Am fully aware that a CN6 or CN66 is 219mm deep, but the depth of lintel in this instance has nothing what so ever to do with roof timbers whether she is a cut roof or trussed.
    Nine times out of ten, storey height is 2400, top of frame is 2100. Depth of lintel 219mm, 6mm tight bed and 75x100 plate gives you 300mm above top of frame.
    If you want to seal cavity with lintel stick a CN81B, for 225mm external walls, 219mm deep with 195mm soffit.
    oldun ;)
     
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    DIYnot Local

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