How to replace timber screening fence over brick wall?

Question

Hello,

I am replacing a timber screen which is on top of a brick wall. The brick wall is I am guessing 60 years old.

I want to install 100 x 100 H4 hardwood posts at approximately 2.4m centres at 2.7m high on top of the brick wall.

What fixings do I need to secure the posts and is the timber I have chosen the right one or is it too heavy? Would I need to brace the structure at this height?

The existing structure is anchored to the wall at the galvanised gate and to the house at the far end.

Thank you.

Grant

R4addZ · Answer

Hi @Grant_C

Fixing the posts directly to the wall is probably not the way to go as any fixing is going to rely on individual brick adhesion (how strong the mortar joint is). This is why the existing fence is constructed the way it is, the base of the fence is (I'm guessing based on the pictures) a single length of 150 x 100 and this will probably be bolted down at multiple points along it's length.

MitchellMc · Answer

Welcome to the Bunnings Workshop community @Grant_C. It's terrific to have you join us and many thanks for your question on fence construction.

The most effective way to recreate the screen will likely be using a similar method to the original structure, so I’d suggest first verifying exactly how the existing posts and frame are attached before dismantling it.

Generally, it’s quite difficult to securely attach a fence directly to the top of an older brick wall, as there’s usually no great structural method of fixing posts to brickwork alone. I suspect a lot of the rigidity in the current structure comes from its attachment to the house, the galvanised fence/gate, and possibly even the deck framing below. Once you start removing the existing screen, you may find the posts are tied into the deck structure or other framing elements.

Regarding your proposed materials, the 100 x 100mm H4 hardwood posts should be suitable for the application and height. You could potentially use bolt-down post anchors such as the Pryda Heavy Duty Bolt Down Post Anchor to secure the posts to the brickwork:

https://www.bunnings.com.au/pryda-100mm-m10-heavy-duty-bolt-down-post-anchor_p0503054

That said, when using bolt-down post supports on top of a wall, it’s essential that the screen structure is also connected to stable adjoining structures, such as the house or existing fence, to prevent movement and reduce stress on the brick wall. At 2.7m high, some bracing or rigid framing will almost certainly be required to prevent sway, particularly in windy conditions.

Let me tag @Remarka6le, @jasonlee, @BriefObsessions, and @trippple, to see if they have any thoughts.

Please let me know if you have any questions.

Mitchell