Installing small fence on top of block wall with future proofing for lean to?

Discussion in 'Landscaping and Outdoors' started by Spooon, Dec 31, 2020.

  1. Spooon

    Spooon New Member

    Hi,

    Pretty much as the title says. I need to install a small fence on top of an existing block wall... Our dog has realised it can jump the wall and head straight over the road into the woods. The run is about 14m in total and the wall currently is 1.2m at its highest point. Will not need raising by more than another 1.2 at any point. I'd like to leave myself the option of installing a lean-to on a section of the wall/fence at a later date. The wall is sound and solid.

    Can I fix 4x4 timbers straight into top of block (via concealed galvanised brackets, or U-shape) which are drilled/bolted/chem-fixed down and them build fence on that. Leaving the 4x4s longer in the area which I eventually want to build a covered walkway/lean-to.

    Or, as I suspect, will this compromise wall structure and I'm going to have to attach posts along the side of the wall?? Can I at least notch the 4x4s so I dont have a full 4 inch of timber sticking out from the wall? Alternatively, should fix a timber horizontally along the length of the fence and essentially create 'stud-work frame for fence and lean-to?

    Any help/advice/links to relevant hardware greatly appreciated... I've got pics to add to post once I've figured out how to resize :D

    Cheers :)

    E2a pic -
     

    Attached Files:

    Last edited: Dec 31, 2020
  2. Spooon

    Spooon New Member

    Couple more pics. Hope that makes sense of it
     

    Attached Files:

  3. spannerw

    spannerw Screwfix Select

    As you say drilling into the wall will weaken it, best bet is to dig down beside it and put your notched posts in the ground.
     
    Abrickie and Spooon like this.
  4. Spooon

    Spooon New Member

    On my side is solid patio and concrete so digging down would be a pain that I'd rather avoid. Can't fix to the outside, it's a field entrance which isn't a mine.

    Would I be able to pin notched posts to the wall face, or is thar just going to still weaken it?

    Also, how much notch can i get away with? If I notched out a 4x4 by half, would the 2inch be enough to pin to the wall, if it was say at least 3ft long (or as close to ground as possible without digging in
     
  5. spannerw

    spannerw Screwfix Select

    Personally if it was mine I would be getting a breaker out and digging holes,( that’s what I used to do for a living so no big problems). However you could drill right through the wall and use 3x3 posts and long bolts or threaded rod, that way you are not putting too much pressure on the wall, which you would if you used some sort of rawl bolt.
     
    stevie22 and Spooon like this.
  6. chillimonster

    chillimonster Screwfix Select

    +1 to spannerw, I still do it for a living, did a run of 11 posts two weeks ago.
    Not a welcome option if you dont do it. I would go for the 3x3 posts and screw
    through them into the wall . As its an outside wall I assume they didn't use
    those lightweight indoor blocks ? So the blocks should stand up to it. I use
    masonry bolts for this situation.
    ps I would fit fence panels in this situation not the heavier featherboard and
    arris rail method. My opinion.
    I'm a dog owner too.
     
  7. spannerw

    spannerw Screwfix Select

    Or if it gets windy in your area chainlink might be a better option.
     
  8. Spooon

    Spooon New Member

    OK, thanks for the advice. What I might do... To save time and my patio, is only dig in the posts that will form the uprights for the lean to, then I can frame off from the side of the house to those. Might use 4 inch posts for those.

    The rest of the run I might do in 3x3s and bolt through as suggested. I was possibly going to do horizontal boards with a space, to still allow some light to filter through and I thought perhaps it might ease the pressure from any wind?

    Am I right in thinking 1.8m for my post spacing? Bolts every 400?
     
  9. spannerw

    spannerw Screwfix Select

    Yes for post spacing,s and bolts. Show us some pics when finished.
     

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