Mortar bed depth..

[johnc86]

Hi. I am extending a double skin garden wall and want to cut the new bricks into the existing wall. I want the first course of the new part of the wall to be 1 course lower than the original wall as it will be easier to keep the footings bellow the soil level.
Basically I've pored a concrete footing into a channel at a depth of about 600mm deep by 400mm wide. I've measured up and the footing isn't quite high enough.
I'm wondering whether to add more concrete to raise it up or whether I can just lay a thicker bed of mortar for the first course and raise it that way. It would make the first course 25mm give or take a few mm.
Is this too thick for a mortar bed or would it be ok?

 

[Alastairreid]

Just make your mix a bit stiffer to level out your 1st course and it will be fine.

 

[johnc86]

Cheers. When you say stiffer do you mean more cement in the mix? would you go thicker than 25mm if needed or is that about the limit?
If its more Im thinking I can always make the second course a little bit thicker as well to get it bang on

Cheers.

 

[Alastairreid]

Less water in the mix to make it less runny otherwise your brick will go out of level on a heavy bed.

 

[johnc86]

That makes sense. I suppose you'd have to get the mortar fairly level before placing the bricks down onto it as its going to be less easily compressed once there sat in place?
Was also just wondering about shimming it up? Is that possible? I've seen slate used in old walls. Or, maybe lay the first course of bricks on their sides to give the extra height?

 

[Alastairreid]

Youre overthinking it...lay your bed of mortar a little stiffer to required thickness, lay the brick and level out to align with existing course.