Building against a retaining wall (nothing special)

[Mercutio]

My garden drops off pretty significantly downhill so is tiered.
The drop from the top to the first tier is about... 2 metres.

The retaining wall is brick with weep holes along the base of it.

If I was to build something up against this wall would I be best:

1) Leaving at least the weep holes free
2) Leaving a small air-gap and putting another skin of wall down so any moisture behind the retaining wall can't wick onto the new stuff I'm building
3) Putting some form of coating on the wall/some form of insulation between the existing wall and the new bits I want to build.

Basically... nothing fancy but I want to stick a decent brick built bbq against this retaining wall. Wondering if I can build against it (would still put a back on the BBQ not using the existing wall on the back) or if I need to leave a gap and use a bit of slate/similar on the back wall of the bbq to neatly cap the space to the retaining wall.

Suggestions/etc most welcome.

 

[Shaz]sigh[]

The weep holes aren’t about moisture on the bricks but more ensuring your foundations aren’t saturated and wont start shifting. If you want to build against it you could drill out the weep hole, build then drill through both skins and piping or conduit to allow the drainage? This is all based on the fact I assume the weep holes are max of say a foot up and your bbq will have a space at the bottom to drain