Retaining wall foundations

[cmulley]

Hi.

I have started a DIY project to level my sloping law into two flat tiers with a retaining wall and have very little landscaping experience (but have been doing a lot of research) . I think I am mostly understood on the drainage requirements behind the wall but I have been reading mixed things about the footing requirements.

The wall is holding back about 600mm of earth, we have a heavy clay soil, and I am planning to build using a single layer of 7N bricks (so that the wall is 225mm thick).

Where I am at currently with the base requirements is that I think I need to dig a trench around 300m deep and 450mm wide. Then pour C20 mix concrete to 150mm thickness, then add courses of 7N bricks on top. I'd appreciate any advice on whether the depth and the thickness of the footing is reasonable and also whether I need to add a sub base to the footing or whether pouring on top if the heavy clay is sufficient?


Thanks in advance!
Chris

 

[freddiemercurystwin]

Sounds reasonable to me, I wouldn't bother with a sub-base, go deep enough to bear your concrete onto solid undisturbed ground. Consider how you will finish the wall and if you need drainage or a barrier behind, or drainage through the wall and how you want to finish the face of the wall, walls that get wet seldom look pretty long term if rendered. Plenty of other threads on the forum to search with regards to finishes of retaining walls etc ....

 

[cmulley]

Awesome thanks for the advice and good to have some peace of mind before I crack on! I was planning to put landscape fabric over the earth behind and a waterproof membrane behind the wall, perforated pipe at the bottom, a few weep holes, and backfill with gravel just behind. Plan was to render and paint but might go back to the drawing board on the finishing. Does render usually look poor due cracking as a result of the damp?