1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Hole size for masonry screws into Victorian brickwork?

Discussion in 'Tools and Materials' started by PaulUszak, 8 Apr 2016.

Tags:
  1. PaulUszak

    PaulUszak

    Joined:
    7 Jun 2015
    Messages:
    230
    Thanks Received:
    6
    Location:
    Staffordshire
    Country:
    United Kingdom
    I'm looking to install a key safe onto the side of a house built circa 1900. The manufacturer suggests a 5 mm hole for a 6 mm masonry screw. That seems a general guide, and I know that these types of fixings are sensitive to hole sizes.

    The house is made of bricks so hard that they ring when you whack them with a hammer. They might be engineering bricks. I'm concerned that the key safe provider is thinking of modern houses made of modern (effectively mud) bricks. What would the appropriate hole size be so I don't mess up?
     
  2. Sponsored Links
  3. Burnerman

    Burnerman

    Joined:
    7 Feb 2008
    Messages:
    21,919
    Thanks Received:
    4,239
    Location:
    Northumberland
    Country:
    United Kingdom
    Why not use 6mm plastic plugs? If the wall is soft, go for a 5mm hole first before increasing to 6mm.
    John :)
     
  4. foxhole

    foxhole

    Joined:
    14 Mar 2006
    Messages:
    16,402
    Thanks Received:
    1,837
    Location:
    Kent
    Country:
    United Kingdom
    The construction has little bearing on the hole size.

    You said
    That seems a general guide, and I know that these types of fixings are sensitive to hole sizes.
    Care to explain?
     
  5. catlad

    catlad

    Joined:
    29 Jul 2011
    Messages:
    4,214
    Thanks Received:
    581
    Location:
    Lancashire
    Country:
    United Kingdom
    Start off small and widen if necessary with 0.5 mm increments, I would also splay the screws slightly.
     
  6. PaulUszak

    PaulUszak

    Joined:
    7 Jun 2015
    Messages:
    230
    Thanks Received:
    6
    Location:
    Staffordshire
    Country:
    United Kingdom
    Firstly, "...house is made of bricks so hard that they ring when you whack them with a hammer..."

    Secondly, there is no choice. You have to use the supplied masonry screws in order to maintain the Police accreditation and manufacturer's warranty.
     
  7. Sponsored Links
  8. PaulUszak

    PaulUszak

    Joined:
    7 Jun 2015
    Messages:
    230
    Thanks Received:
    6
    Location:
    Staffordshire
    Country:
    United Kingdom
    I don't understand how this might work. How would I know when it's necessary to widen without having driven the screws in? If they go in, fine. But if they don't and there is a problem, then the substrate might be messed up or the screw sheared off. Then it might be necessary to widen the hole by several millimetres and use larger screws. I've never used masonry screws, but I'm under the impression they are a one shot type of fixing.

    I'm also not sure how you widen a hole in 0.5 mm increments. Doesn't that just cause the drill bit to screw itself into the hole?
     
  9. PaulUszak

    PaulUszak

    Joined:
    7 Jun 2015
    Messages:
    230
    Thanks Received:
    6
    Location:
    Staffordshire
    Country:
    United Kingdom
    Well they're not like a fibre /plastic plug /expanding bolt that expands. That allows some latitude in the hole diameter and the fixing still works (albeit perhaps with varying effectiveness). With a non expanding threaded screw going into non yielding brick they can only be a little overlap for the screw to work effectively. I would have though that it would be extremely difficult to drive home a 5 mm masonry screw into a 6 mm hole in a solid steel plate. I think that the house is made of steel bricks. Therefore the construction must matter?
     
  10. Burnerman

    Burnerman

    Joined:
    7 Feb 2008
    Messages:
    21,919
    Thanks Received:
    4,239
    Location:
    Northumberland
    Country:
    United Kingdom
    Ok, I was unaware of any Police accreditation requirements.
    Why not do a test drilling, 5mm, in the area which will be covered by the key safe? It doesn't matter how hard the bricks are, a quality SDS drill and bit will get through. Test that drilling with a spare screw.
    John :)
     
  11. foxhole

    foxhole

    Joined:
    14 Mar 2006
    Messages:
    16,402
    Thanks Received:
    1,837
    Location:
    Kent
    Country:
    United Kingdom
    No, its a simple job.
    No chance of snapping a masonry screw, they should be hardened.
     
  12. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
Loading...

Share This Page