Securing a Fence post ontop of a Patio

Discussion in 'Builders' Talk' started by Andrew Humphries, Apr 8, 2020.

  1. Andrew Humphries

    Andrew Humphries New Member

    Hi all, I want to Secure a 4ft Fence post ontop of a patio. I was planning on securing a Bolt Down post Support, Drilling through The Paving slab, then either use 150 mm Thunderbolts, or drill as far as I can and Drive a threaded rod into the hole, and secure using that.
    I'm note sure how deep I'll have to drill to get through the base Layers of the patio.

    It will form part of a larger fence, and will be the only Fence post not Secured to a Wall.

    The fence itself will be made of decking boards - and will be no higher than 4ft.

    Question is, will this work - will it be strong enough? I have some Vinylester Mortar that I was considering putting in the Drill holes to make it as strong as possible, But I've never secured on top of a patio before, so unsure they best way to do it!

    Any help would be much appreciated.

    thank you
  2. cleggie

    cleggie Active Member

    instead of securing on top of the slab iw ould remove the slab then dig out a couple of feet into ground put in the post and fill in with postcrete.Then with the slab i would mark out and remove the piece for the post so i could lower it over the post.
    Jord86 likes this.
  3. ramseyman

    ramseyman Screwfix Select

    Cleggie’s reply would be a much better option
  4. Kas228

    Kas228 Screwfix Select

    Definitely right thing to do but will depend on what tools and equipment you have in order to cut the paving slab to the correct shape. Also if the post sits within a complete slab could be a pig to cut out a central square.
  5. Kas228

    Kas228 Screwfix Select

    Alternatively you can buy post holders that affix to slab
  6. robertpstubbs

    robertpstubbs Screwfix Select

    Could make a round hole with a core drill. Diameter of hole would need to be 1.414 times the side of the post.
  7. Jord86

    Jord86 Screwfix Select

    Use an angle grinder to remove the square from the slab.
  8. Andrew Humphries

    Andrew Humphries New Member

    Thank you very much for all your Replies!
    I have further questions though..

    At this moment, I am unsure if I can remove the paving slab - it's a relatively new patio so I'm expecting it'll be difficult to dislodge and would like this as last resort.

    Kas228, What post holders would you recommend? and how would you fix them?

    robertpstubbs, If I made a large hole with a core drill, What would you then use to Fix the post - a support with a drive in spike ?
    Or would you still recommend excavating using an auger and filling with postcrete? .
    I am favouring this idea at the moment, and think that it would be the best fixing with what I have available.

    sorry for my ignorance, but as I say, I'm new to this type of work!

    Many thanks again
  9. Andrew Humphries

    Andrew Humphries New Member

    I thought of this, but then fix the post how, using a drive in spike post support?
  10. Jord86

    Jord86 Screwfix Select

    No, cleggies advice was the way to go in post two. Mark on the slab where the post is to go using a thick pencil or whatever, Remove the slab, use the angle grinder to cut the joints out if needs be, dig out a hole underneath for the post, fill with postcrete and gravel, plop the post in, strut it plumb and leave it to go off. Cut out the marks on the slab you took up with angle grinder, then relay with 4:1 sand and cement, slide it over the top of the post. Point it up when mortar has gone off.
    stevie22 likes this.
  11. robertpstubbs

    robertpstubbs Screwfix Select

    I had assumed drilling a hole in the slab whilst removed just big enough to fit round the post.

    Thinking more about it, you could actually drill the hole with the slab in situ. In that case you would need to make sure the hole was big enough for tools and hands.

    I would excavate a hole and use postcrete.

    A round hole in a slab is less likely to cause cracks than a square hole, especially if there is overcutting with an angle grinder.

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