Brick crumble

[DIYspanner]

Its a double skin boundary wall with a fence standing on it. The level on the inside is a couple of inches below the coach bolt heads which I've put all the way through the wall with fence rails on the other side so the wall is clamped so to speak.

A number of bricks surfaces have crumbled. Is rendering the wall with mortar or applying brick slips the best way to tidy the wall's appearance?

 

[matlob]

If the ground height over the wall is up to the coach bolts it may be that there is no drainage on the other side or insufficient drainage paths through the wall. It looks like you may have drain holes but could just be blown mortar

What is the build up of ground on the other side?

It's usual to have engineering bricks on top of a wall or an overhang to allow water to run off easier.

Ideally need to work out why it's crumbling before covering it up as it will just blow again

 

[DIYspanner]

The ground height on the other side is one course down from the bolts. Its a path along the side of the property's garage side wall. The path is a single row of flagstone with gravel borders on both sides.

As the photo shows, there are what looks like drain holes in the lower brick course so perhaps I need them clean out. I don't know what type of brick was used to build the wall. The property is a 2003/04 build.