Best way to put up garden fence?

[HannibalSmith100]

I currently have breeze block (party) walls on either side of my rectangular garden - one side is 3ft high and the other is 4ft high. I’d like to increase privacy by putting up some fencing panels to take the overall height up to about 6ft all around the garden. I have therefore already bought enough 6x3ft panels to go around and supplement the wall height.

With there already being a fairly solid wall in place around the garden, I was hoping to avoid having to sink 8ft fence posts into the ground and instead would prefer to bolt 6ft fence posts to the walls using masonry bolts, with the fence panels then being attached to the posts (not directly to the wall themselves). My original plan was to raise the fence posts off the ground by an inch or so (to avoid ground water rising up through them) but this would mean that the total weight of all posts with adjoining panels (along with any wind force) will have to be borne by the walls entirely. One of the walls is 37ft long requiring 7 posts and 6 panels, the shorter wall (a concrete shed in the corner of the garden separates this from a non-party back wall) is 32ft long and will also require 7 posts and 5 (and a bit) panels.Having felt the weight of the panels and posts I’m starting to think it might be quite heavy for everything to be bolted to the walls, although it’s possible that the posts at either end of the walls could also be bolted onto the house and/or concrete shed for added support.

The walls are a single breeze block wide (just under 4 inches) but are supported lower down by buttresses every 10ft or so along, which more than doubles the width at those points. The walls are in good order and I’m confident they can easily support the total weight of the fence, I’m just worried about the added wind force on top of this possibly having a detrimental effect on their integrity over time. The attached photo shows the wall positions and width, with both walls coming back the full length of the garden on either side of the conservatory.

The garden is fairly well sheltered but is at a right angle to the prevailing wind direction so in stormy conditions the fencing could take a battering. By the way, the fence panels are the overlap type so unlikely to allow wind to pass through very easily, although they will be positioned away from the wall slightly to leave a small gap in-between.

Would my original plan to bolt everything to the walls be sufficient or would I need to provide additional support, either by adding bolts through the end posts into surrounding structures or by sinking a few 8ft fence posts into the ground with concrete to help distribute the weight? Would really appreciate some feedback on this before I go ahead with anything. Thank you.

 

[Ric2013]

I don't think your walls have any architectural merit, so the only thing you're risking is that the foundations are not sufficient and they start to lean, or that they snap off at the base and then you get the opportunity to start from scratch anyway. But, given that on one side you'll only be raising it 2', I think it's fairly unlikely to be a problem. That said, a trellis would allow more wind through and you could plant a clematis or similar, and achieve privacy and decoration at the same time.

If you say they are party walls, though, you can't just use them to support a further 2'-3' without the other owner's agreement. I assume you know that and that's why you're keen to get it right.

 

[r896neo]

Your concern about weight is irrelevant. The walls are super strong in compression.

Your problem is the wind loading. A single skin wall has almost no strength against an overturning force and adding a sail on top is a bad idea. The panels will probably pull the wall over in windy conditions if you attach them to it. A 9" wall at these sort of heights might be ok but a 4" wall is a big risk.

I would put in posts about
30mm from the wall and keep the two separate.

 

[HannibalSmith100]

Thanks very much for your replies Ric2013 and r896neo – not what I was hoping to hear but glad I did before I started bolting the fence posts to the walls! You’re right Ric, with these being party walls I want to make sure I do everything properly and it’s now clear that I just need to leave them alone! We’re hoping to move in a few years' time and I certainly don’t want any party wall issues to complicate things. Plus getting the neighbour's agreement on any work would be difficult as they're both rented out - I haven't even met the owner of one side in six years of living here.

Having already bought some 6ft posts and masonry bolts I’ll use what I can to attach any end posts to my property alone, but the rest of the posts will be 8ft ones which will be concreted into the ground away from the walls instead. I’ll feel better knowing everything is on my property then and not having to worry when it gets windy!

Appreciate your input on this and helping me to make a decision.

 

[Ric2013]

Hannibal,

Your neighbours, by law, will have contact details for the owner of the property, even if just the address. So contacting the owners could be an option.

That said, I know where you are coming from. Party anything can very well be a PITA. I made the mistake of allowing a neighbour to replace a 4" gutter on my porch with a 3" one when he built the walls of his porch and realised he hadn't allowed enough clearance (red flag?) for his roof. 3" was more than adequate for the job, but he did the work in an arse-about-face way that means maintenance or replacement of my gutter will now be next to impossible. I'm sure he thinks it's fine.

Now he's asked me if he can externally clad the outer wall of his extension (because he built it as single skin and now it has condensation issues, surprise surprise) such that he'd be prepared to buy a strip of land off me to do it. Since this means his cladding would then be overlapping the rear elevation of my house (which, itself, has structural issues because the previous owner of my house dropped a lot of rubble down the cavity), and since I don't trust him to do it properly anyway, I have a short answer for him - shorter than a yes anyway!

Just make sure you don't end up relinquishing your right to the remaining gap between the walls and your new fence - could you store, say, bean sticks or canes between the two so you are obviously still using the land, or label the outside of the new fence 'Boundary extends x inches in front'?

 

[Tigercubrider]

Did you keep the receipt?

Trellis might be a solution

 

[HannibalSmith100]

Thanks for letting me know about contacting the owners Ric, that could come in handy later on a few issues involving our shared porchway and guttering. Hope you get to the bottom of the problem you're having, sounds like it's getting a bit awkward!

I'm hoping there won't be any boundary issues once the fence is up. It's pretty obvious that the wall is the boundary line and I think it'd be unlikely that the neighbours would want to encroach on that. I have a clear view on the other side of the fence from the road so will know if anything has been added/altered at least.

I definitely want a fence rather than trellis as it'll provide instant privacy and means I don't need to wait for plants to grow. The idea is to then fill the garden with a few pot plants to break the lines up a bit. I've already started painting the panels with preserver before I put them up anyway so taking them back is no longer an option. I was able to get the 6ft posts refunded and bought the 8ft posts at a cheaper clearance price so the extra money has helped towards getting the bags of postcrete. All in all I should just about break even compared to my original idea.