I live on a corner home and the street/sidewalk on the right side of my home travels up a slope. The way my yard is currently designed, the right half of the yard follows the same slope, but not the left, almost at no angle at the front of the yard, but at an increasing angle as one goes towards the back of the yard. The pictures probably explain it better than my words.. in any case, what I want to do is add a retaining wall and remove excess soil in order to flatten out the lawn area. Due to the slope, the wall would also need to be sloped. There is a small section of block wall at the highest point of the front yard area, that I could remove if needed (I'd consider some white picket style fencing to ensure nobody "falls" into my front yard from the adjacent sidewalk), but if I didn't have to remove the wall that would be even better. I don't want to cut in from the existing wall as my yard just isn't wide enough for that to make sense in my opinion. Is there a way to build a sloping (not stepped) retaining wall (maybe concrete with some form of decorative facing) so I can have a flat yard (I want to install new sod and sprinklers as the next project eventually.. and yes the palm tree will be going away and I'll be tweaking the fence between the front and side yards too). Any suggestions or ideas would be appreciated. Thanks!
Walls – Retaining wall on a 2-way slope under an existing block wall
slopewalls
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It's really hard to say without being there in person. The wall certainly looks unstable and ready to be taken down, but a lot of concrete walls can look terrible, but still be structurally sound. We owned a house with a concrete block wall reinforced with rebar that had perhaps a 10 degree lean outwards that looked like it'd fall any day, but it took a LOT of sledge hammering, chiseling, jacking, and gas-powered diamond-blade cutting to actually get it out. It likely would have stood for another 50 years on its own.
In your situation, it appears that you've lost all the earth around your footing. At this point, it may be a lost cause and you'd be best taking it out. Ideally, you'd then replace it with a stepped retaining wall using a dry-stacked block. The dry-stacked blocks are a) easier to install and b) when installed properly will allow water to drain through rather than build up behind the wall pushing it out.
All that said, it appears that your neighbor has build a foundation right up along your wall. I don't know where you live, but I'd think in a lot of places that'd be against code (you typically can't build that close to the property line). In addition, it seems risky for them to depend on you to hold up their foundation with your wall. Seems that they should be bearing part of the ownership of whatever is retaining the earth on this property line.
Finally, if that's a down-spout in the lower photo emptying between the two walls, then a) take it up with the city, as that is likely also breaking all sorts of code regulations and b) your neighbor really should be worried about that. You don't want a downspout draining near the footer of your new kitchen's foundation.
I built a retaining wall in a situation very similar to what you described. In my case the wall drops approximately 12" over 40 feet. It has 3 courses of 6" Keystone wall blocks. The first course is mostly buried and the wall is about 12" high over most of it's length. I also put about 4" - 5" inches of drain rock behind it with a landscape fabric barrier.
This was 15 years ago and it seems to be holding up just fine. I would hope that the 4" blocks you want to use will be ok. However, I've worked with that size some doing garden walls and they are definitely less stable than the bigger blocks.
One other consideration here is aesthetics. Make sure looking at a retaining wall that isn't level doesn't bug you! Sometimes I look at mine and wish I had installed it level and stepped it down instead.
In the area where I live we have an assortment of gravity block retaining walls and the ones that follow the slope usually don't look as good in my opinion.
Here is a photo for reference:
Best Answer
What's behind the wooden fence, your back yard? Does the slope get even taller back there? Would you dig out that slope and continue the retaining wall there? You can reasonably build a retaining wall 3-4 feet high without major engineering but when you get to 6-8 feet high it has to retain much more weight (8x as much according to This Old House) and takes more engineering. This may be more than you want to get into.
As Alaska man asked, is the tree next to the sidewalk yours, or is it the city's? What do you plan to do with the brick wall? It would need to be supported or removed also. Would removing the tree or brick wall require city permits or an engineering study? This may also be more trouble than it's worth.
With palm trees and bare dry dirt, I'm guessing you're in a dry area in the south western United States. I'm in the central U.S., where we have thunderstorms 8-10 months out of the year. A good thunderstorm or two would wash that loose dirt slope down against the house and risk toppling the brick wall so I would leave the slope as-is and sod it or put in low ground cover to hold the soil in place. If I used grass I would then have to mow it. I prefer a smooth slope I can just push a lawn mower up, rather than have to pull out a string trimmer for a few square feet of grass on top of a retaining wall. For long-term durability and ease of maintenance, I'd recommend just adding sod or ground cover and leave the slope alone.