Flat roof fall

Discussion in 'Carpenters' Talk' started by Bilaal, Sep 30, 2020.

  1. Bilaal

    Bilaal New Member

    Hi Guys,

    So just needed some help with my firrings basically ive got a 6m long flat roof that leads to 1 gutter in the parapet and i need to work out the firrings ratio im doing a warm roof and wanted to know the ideal ratio/slope needed for the 6 meter fall any help would be apreciated. roof is having a lantern fitted


    Thanks

    Give me a call if you can so i can explain it all a little better if needed.
     
  2. Abrickie

    Abrickie Screwfix Select

    Tapered insulation boards ? ;)
     
  3. Severntrent

    Severntrent Screwfix Select

    Road drainage has a camber of 1 in 40, minimum slope for sewerage pipes 1 in 80, rainwater off roof 1 in 120. i.e. 50mm in 6m
     
  4. rogerk101

    rogerk101 Screwfix Select

    If your ceiling 'follows the fall' if the warm roof above it you wouldn't even notice the drop of 50mm over 6m.
     
  5. stevie22

    stevie22 Screwfix Select

    Standard fall for a flat roof is 1 in 80 but we usually adopt 1 in 60 to avoid the risk of hollows if the roof deflection is on the high side. This equates to 1 degree. You need 100mm fall.

    Use firrings and keep ceiling flat you will see it and it will wind you up. (Daughters rear extension done like this so voice of experience)
     

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