Retaining Wall slope

**BjornMiller** · 14th January 2008, 07:14 PM

I am installing an ironbark (hardwood) sleeper wall. It varies in height between 600 to 800mm high and has posts on the outside of the wall.
I have done a lot of investigation and found the best information source provided by Timber QLD. Timber Garden Walls

From previous postings on this forum and this tech sheet it advises that the wall should be on a 10 degree slope to handle the backfill presure. I am happy to do this however am unsure what to do with the corners. I have 4 90 degree corners and am wondering how each side will join without gaps appearing at the bottom.

As per the illustration in the tech sheet I have 2 posts on either side of the corner (right on the edge).

Two ways I can think of is to cut the posts to allow them to butt together allowing for the 10 degree slope of the adjoining wall. Or the second is to move the posts back from the corner and cut the wales (horizontals) to meet without gaps.

I hope this makes sense as it is very hard to describe an idea in writing

Cheers
Bjorn

**joe greiner** · 14th January 2008, 11:15 PM

As I understand it, you want to have intersecting batters at the corners. I suggest placing the SECOND post from each corner at the allowable wale length from the corner. Connect the full-length intersecting wales with compound miter or butt joints according to your taste as they show for garden edges. Place the FIRST post from each corner at about one-fourth the distance to the second post. This would provide pretty much the optimum balance of stress in the wales. Cutting the end posts according to your first concept would likely weaken them too much.

Joe

**Tubby2** · 15th January 2008, 02:06 PM

Originally Posted by BjornMiller

.....this tech sheet advises that the wall should be on a 10 degree slope to handle the backfill presure.

I think a 1 in 10 slope as the article suggests is different from a 10 deg pitch

**Edit I see that it mentions 1 in 10 batter for walls over 400mm which is a tad short of 6deg. It does show 1 in 6 batter in the diagram for the ground level above and below the wall which is close enough to 10deg but the actual retaining wall doesnt need to be 10deg.

Going back to Year 10 Trigonometry 1:10 batter equals a 5.7deg.

**BjornMiller** · 15th January 2008, 09:05 PM

Thanks guys for the reply - I assumed as much with the corners so someone else thinking along the same line is much appreciated.

And thanks for being precise Tubby.

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