Wall and fence

JackMN

Two questions:
1. Is there much of a risk in attaching a light fence to a brick wall? My concern is that it's only a 4inch thick wall and is mortar not cement? The fence would be about 3 feet above the wall and attached by battons. The wall itself is about 4 foot tall. A few people have looked at it and one of them said that in a gale the fence could pull the wall down...?

2. Separately: how much foundation does a wooden post need if it is to be 2.3 meters above the ground? Should it be another meter below the ground?

sydthebeat

Please explain "mortar not cement"?

"mortar" is a mix of sand and cement.... Usually called concrete

sydthebeat

Also, a fence 2.3 m above ground requires planning permission

looksee

Approximately 12 to 15 inches of ivy growing along the top of a 4" wall pulled down the entire wall in a quite minor gale. I'd say a well fastened fence (ie the fence isn't going to give) would bring down a 4" wall no problem.

JackMN

Wow. That sounds like I'll have to put up a fence independent of the wall.
Just to be sure: the wall that was pulled down was a 4 inch thick wall?

Lumen

What you're describing is called a half brick wall.

There's a handy table of maximum recommended heights here:

https://www.gov.uk/guidance/your-garden-walls-better-to-be-safe

Apols for the Brit links but bricks are more common in the UK for various interesting reasons so the guidance is easier to find.

https://www.brick.org.uk/admin/resources/s-free-standing-walls.pdf

You can see that the maximum recommended height varies by location (roughly correlated with wind exposure), and that your half brick wall should be no taller than about 400mm, although piers will increase the "effective depth" of the wall.

The height you're describing requires 300mm block with piers depending on length, and foundations double that width.

It's complicated by the fact that you're attaching fence rather than just building a tall wall, but basically what you're proposing is unsafe and illegal.