Help with blockwork retaining wall

[bhwh]

Hello to all! This is my first post so go gentle!

Seems like a popular question this and I have spent a great deal of time reading previous posts and info on pavingexpert.com. However, the more I read the more I get confused and doubt myself. Oh dear.

Anyhow, I am constructing a garden retaining wall that will also act as a raised bed, made from heavy concrete blocks to be eventually rendered/painted. The height of the wall is approx. 2.5 - 3ft and is approx 18ft in length (although this does include two protruding 'bays' and a recessed area between them i.e. the wall is not simply a straight line).

1. So far my trenches are 600mm wide and will allow for 150mm depth footings with 150mm of blockwork underground (frost protection). Is this sufficient?

2. I want to use a double skin concrete block wall at the base and then reduce this to single blocks higher up. What bond do I use to lay the double skin or do I just tie the two layers together somehow? Fill the cavity with more concrete? Or just lay the bottom block on flat edge and then go single blocks? Any suggestions?

Everything else I'm fairly happy with unless you have any suggestions!

Many thanks in advance.

Ben

 

[The-brickie]

1. So far my trenches are 600mm wide and will allow for 150mm depth footings with 150mm of blockwork underground (frost protection). Is this sufficient?

Yes

Or just lay the bottom block on flat edge and then go single blocks?

Yes, its the strongest way.

Are you going to treat in side of the wall with a waterproof membrane?

 

[bhwh]

Yep - membrane, perforated pipe and type A gravel all sorted (topped with hardcore backfill).

So basically, with those footings I'm doing the right thing. That's good news.

With regards the base blockwork, http://www.pavingexpert.com/featur03.htm shows a diagram of a thicker lower section. But you reckon just one block face down will suffice?

Thanks for your help and reassurance!

 

[The-brickie]

You could do a few more block on face courses, the more the better really and maybe just the top course laid 'normal' to make it as strong as possible.

 

[bhwh]

Nice one. Hadn't thought of that.

I'll do three or four face down courses then revert back to normal.

Thanks for the help.