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Counter batten requirement on dormer

Discussion in 'Building Regulations and Planning Permission' started by Bowlzi, 15 Aug 2017.

  1. Bowlzi

    Bowlzi

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    Hi, building inspector said that they "like" to see counter battens for newly clad dormers in case of moisture on the battens...
    It's messed all my measurements up on tiling but can't find anything that says it is a legal requirement?
    What's the deal. Local, national or just inspectors requirement?
    Cheers
     
  2. tony1851

    tony1851

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    There's no 'national' or 'local' requirement in the Building Regs - it's just a case of what's suitable and there are many ways of skinning a cat.
    But good practice is to use vertical counter-battens first, then felt, then tiling battens.
     
  3. Bowlzi

    Bowlzi

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    Thanks ,
    I may have made a mistake already then by putting membrane then vertical battens ... It's on a dormer with sheathing ply
     
  4. freddiemercurystwin

    freddiemercurystwin

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    With vertical battens against the membrane any rain that penetrates the tiles will have a path to run down rather than sitting on the horizontal battens. It's good practice.
     
  5. tony1851

    tony1851

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    ?
    On that basis, what happens on a normal pitched roof, where we put the felt on top of the rafters, and immediately below the tile battens?
    Surely it's cladding/vertical counter battens/felt/horizontal battens/tiles?
    Or have I misunderstood your post?
     
  6. Bowlzi

    Bowlzi

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    I think on a normal pitched roof the membrane hangs loose and creates a valley so that there should be passage for water.
    Difference on the vertical dormer is that the battens and membrane are tight against the sheathing so water would have to go over the horizontal batten and not behind.
    I think then that I should be ok with the way I have done it... :-/
     
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  7. tony1851

    tony1851

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    You could well be right - prob. won't make much difference either way.
     
  8. freddiemercurystwin

    freddiemercurystwin

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    No its board/membrane/vertical counter battens/horizontal battens/tiles. As mentioned on a pitched roof the membrane should sag (hence the minimum 25mm gap required between insulation and top of rafters when a breathable membrane is used) allowing any rain to run down the gap formed by the sag.
     
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