Building piers on top of a wall

[petej42]

Hi.
I'm after a bit of advice on building some brick piers. I have a concrete block wall at the rear of my property. It varies between 3 and 4 foot tall and is 1 block (9 inches) wide.

I want to increase the height to 6 foot all along.

My idea was to build some brick piers on top of the wall and install hit and miss panels in between(it can get quite windy). Would there by any problem with building the piers directly on top of the wall? My thought was either 1 1/2 by 1 brick or 2 by 1 bricks. The existing wall has been up several years and has no sign of movement.

Any advice would be gratefully appreciated

 

[noseall]

Lol. 9" piers with panels between will sail away in the next wind.

 

[Mobo_14]

Done something kind of similar but had to bed 4x4posts in at the back of the piers along the wall.

As has been said strapping it directly to a 9" butt wouldn't bode too well in high winds

 

[petej42]

So to clarify, the problem would be with the panels tearing themselves out of the fixings rather than the piers themselves failing. I am planning on building the panels myself they would be 18 X 95 mm hit and miss boards with 50mm gaps running either side of 25 x 100 mm batons running top and bottom with multiple anchors to the piers. Maximum 900mm in height above the top of the wall and 1.8m in length

Similar to this
https://www.stfencing.co.uk/product/hit-and-miss-windproof-fence-panels-flat/

 

[^woody^]

So to clarify, the problem would be with the panels tearing themselves out of the fixings rather than the piers themselves failing

No the piers fail.

 

[Notch7]

So to clarify, the problem would be with the panels tearing themselves out of the fixings rather than the piers themselves failing. I am planning on building the panels myself they would be 18 X 95 mm hit and miss boards with 50mm gaps running either side of 25 x 100 mm batons running top and bottom with multiple anchors to the piers. Maximum 900mm in height above the top of the wall and 1.8m in length

Similar to this
https://www.stfencing.co.uk/product/hit-and-miss-windproof-fence-panels-flat/

Wind will still exert lots of load on those panels, although the gaps will help release pressure.

Brickwork is strong in tension but has little lateral strength.

 

[tony1851]

Brickwork is strong in tension....!!!!!!!!!!!!!!

 

[Mobo_14]

So to clarify, the problem would be with the panels tearing themselves out of the fixings rather than the piers themselves failing. I am planning on building the panels myself they would be 18 X 95 mm hit and miss boards with 50mm gaps running either side of 25 x 100 mm batons running top and bottom with multiple anchors to the piers. Maximum 900mm in height above the top of the wall and 1.8m in length

Similar to this
https://www.stfencing.co.uk/product/hit-and-miss-windproof-fence-panels-flat/

In the link you sent looks like concrete fence posts being used which would also work

 

[noseall]

The piers in the above image are doing the square root of feckall. They are being held up by the fence.

would be with the panels tearing themselves out of the fixings rather than the piers themselves failing

The piers will fail. Miserably and with consequences if they are adjacent to a footpath.

 

[Mobo_14]

The piers

The piers in the above image are doing the square root of feckall. They are being held up by the fence.


The piers will fail. Miserably and with consequences if they are adjacent to a footpath.

If yer on about the photo I put up I never once claimed the butts were anything but decorative.

 

[Leofric]

Brickwork is strong in tension but has little lateral strength.

bwk is strong in compression but how do you work out bwk is strong in tension ? - what about the mortar joints ! Bwk has little lateral strength

 

[petej42]

Thanks for the advice everyone, been really useful. So now I'm a bit stuck. Brick piers are obviously out of the question (unless there is some way of reinforcing them). Can anyone suggest an alternative that would be more suitable. Ideally I would like the fence to sit on top of the wall as it looks tidier. I have seen examples on the web using thunderbolts and bolt downs for wooden fencing posts on top of the wall and other options which involve fixing wooden posts down the face of the wall and attaching the panels to these - are wooden posts really stronger than brickwork under these conditions?

 

[Charlie George]

Wooden posts will flex in windy conditions, you could use cranked metal posts or extend footing in wall and build bigger pillars tied into existing wall, make pillars at least 1 1/2 brick square, and drill rebar into centre of pillar and concrete.

 

[tony1851]

- are wooden posts really stronger than brickwork under these conditions?

Under high wind, a 1.8m high 215 thick brick wall with no piers will almost certainly fail before a 1.8m high timber fence with 100 x 100 posts @ 1.8m c/s (assuming the posts are well-concreted in).
Why not set timber posts in concrete immediately behind the wall @1.8m c/s without any mechanical fixing to the wall, and put horizontal timber runners between the posts, and fix vertical laths to those. The idea being that the masonry and timber are separate and there is no additional stress being put on the wall.

 

[noseall]

are wooden posts really stronger than brickwork under these conditions?

Yes because they flex before they break.