Fastening wooden fence posts on top of brick wall that is capped with stone slabs

[NY]

I want to fasten a couple of wooden fence posts, about 1.5 m high, with a fence panel fastened between the posts, on top of a brick wall that is capped with stone slabs. The brick wall appears to be made of two bricks laid side by side - I can't be certain without removing a cap-stone, and they are firmly mortared in place. However the width of the slabs is 270 mm, which suggests two courses of brick side by side. The slabs are 25 mm thick.

Sketch:

The main problem will be the amount of sideways leverage that there would be on the posts if a wind like Storm Ciara/Dennis blows on the panel.

I have seen mounting brackets such as

which have four holes.

What is the best way of drilling through a stone slab without it cracking? I presume the best way to anchor the bolts is to use expanding metal bolts. Is it best to try to make the fixing expand into the brick, and not also to expand into the stone for fear of cracking it.

It would be possible to drill a couple of holes horizontally through the wooden post, sideways into ends of bricks that make up piers at the end of the wall, to provide additional fixing for the posts, though these bolts would only be 1 brick above the level of the slabs.

[Tim+]

Attaching a big sail to the top of a brick wall sounds to me like a good way of breaking the wall. Mortar really isn?t that strong in tension!

It would be better to plant two long 4x4? poles behind the wall and then maybe use another bit of 4x4 fixed to the face of the poles to bring the fence line ?forward? to where you want it.

Tim

[newshound]

Agreed. With the caveat that the OP does not say how high the brick wall is (the drawing suggests about six courses). If it really is a small dwarf wall, maybe 18 inches high, then how about drilling a couple of 3 inch holes right down through the capstones and the wall and through the wall footings (assuming it has footings), and setting in place a couple of scaffold poles, ideally hammered down to a couple of feet below ground level. The visible parts of the poles could be concealed with a couple of lengths of 4x2, sandwiching the fence panel in position.

[Jeff Layman]

That's what I would have thought, but I happened to be walking round a new estate being build near here a few days after "Ciara" to see if there had been any damage to fences. There wasn't, surprisingly enough, but as much of the estate is on slopes, I was amazed at the number of 2m fences on top of brick walls ranging from 50 - 150 cm in height. The fence posts were taken down 30 - 50 cm or so below the top of the wall and screwed into the side of it.

[tabbypurr]

that is a classic no-no. Cement mortar has low tensile strength which over time normally falls to zero.

think again

NT