Screw Size for SP101 over old floorboards

Discussion in 'Subfloor Preparation' started by Discoeye, Sep 22, 2022.

  1. Discoeye

    Discoeye New Member

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    Hi all,
    Looking for recommendations on screw size for laying sp101 over old floorboards. [email protected](5.5) and using the equation of 18mm floorboards +6mm sp101 gives me 24mm rounded down to 20mm so I don't go bursting any pipes or making the electrics spark makes sense.

    My overall concern is there is a mix of old and new(ish) floorboards and the house being over a hundred years old i'm worried about pushing my luck with 20mm 3.5 spax screws, could I drop down to 16mm 3.5 spax or are these going to be a little short.

    Any advice will be much appreciated.
    By the way the area is 13 sq metres so 5 sheets @8x4 feather joints then tackifier and Karndean looselay.
     
  2. dazlight

    dazlight Super Moderator

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    I use 19mm ring nails and they only go in a bit so 16mm screws would be ok.
     
  3. Discoeye

    Discoeye New Member

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    Thanks Dazlight I appreciate your help.
     

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