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Cavity wall thickness

  • 29-12-2020 3:20pm
    #1
    ij2000
    Registered Users, Registered Users 2 Posts: 7 ✭


    Hello, I am wondering does the inner leaf of a cavity wall which the end of a hollow core precast concrete slab rests on have to be 215mm (block laid on its flat) or can it be 100mm?
    I seen an article on the selfbuild website which states it is to be 215mm


Comments

  • #2
    Biker1
    Registered Users, Registered Users 2 Posts: 400 ✭✭Biker1


    It's at the discretion of your structural engineer. You will find that in most cases it will be 215mm whether it is required or not.


  • #3
    Gumbo
    Moderators, Society & Culture Moderators Posts: 40,340 Mod ✭✭✭✭Gumbo


    ij2000 wrote: »
    Hello, I am wondering does the inner leaf of a cavity wall which the end of a hollow core precast concrete slab rests on have to be 215mm (block laid on its flat) or can it be 100mm?
    I seen an article on the selfbuild website which states it is to be 215mm

    Your engineer will make the decision on bearing but it will most likely be substantially more than 100mm.

    100mm wouldn’t be enough bearing to comply with the basic requirements of the Building Regulations, Part A.


  • #4
    Biker1
    Registered Users, Registered Users 2 Posts: 400 ✭✭Biker1


    Gumbo wrote: »
    Your engineer will make the decision on bearing but it will most likely be substantially more than 100mm.

    100mm wouldn’t be enough bearing to comply with the basic requirements of the Building Regulations, Part A.

    If an engineer calculates the loads and declares that 100mm blocks are sufficient then they are. Most add in such a high safety factor which makes the use of 215mm blocks necessary.


  • #5
    Calahonda52
    Registered Users, Registered Users 2 Posts: 12,883 ✭✭✭✭Calahonda52


    Biker1 wrote: »
    If an engineer calculates the loads and declares that 100mm blocks are sufficient then they are. Most add in such a high safety factor which makes the use of 215mm blocks necessary.

    Its not a loading issue, its a bearing issue, and the safety factor which you so readily ridicule and disparage has more to do with achieving actual bearings on site, as opposed to theoretical bearings on a screen.
    Anyone who has worked on site and in precast factories will tell that.

    “I can’t pay my staff or mortgage with instagram likes”.



  • #6
    Biker1
    Registered Users, Registered Users 2 Posts: 400 ✭✭Biker1


    Calahonda52 wrote: »
    Its not a loading issue, its a bearing issue, and the safety factor which you so readily ridicule and disparage has more to do with achieving actual bearings on site, as opposed to theoretical bearings on a screen.
    Anyone who has worked on site and in precast factories will tell that.

    It was not my intention to ridicule or disparage anyone and if you seen it that way my apologies.


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