Anyone added a retainer wall to their backyard?

[oldpops]

Hi all! Not sure how to ask this question but here goes: Our housing tract is build in the hills, with a home above us (and below) - which is pretty common here in southern CA. Anyway, the hillside between our home and the one above is nothing but a place for weeds to grow (no-one can afford to water their grass/lawns in California anymore, and using too much water (in the governments eyes) will get you fined. So we're constantly having to pay gardeners to cut down all the weeds & dig out the roots. Unfortunately, the weeds apparently don't need any water and keep coming back.

My wife saw some pictures of what some other homeowners with a similar situation have done: Basically they got a mini-excavator and dug out most of the hill above the retaining wall, (leaving a foot or so). Then they had retaining walls built to hold back the dirt from the house above. Doing this gave them a lot of additional useable space. I am attaching pictures of our little hillside, plus the ones my wife saw - that she would like to do to our hillside.

Not knowing anything about retaining walls, or how much they can hold back (dirt weight-wise), or what is the tallest a retaining wall can be, I thought I would ask you folks her in hopes someone here an offer info, advice, and suggestions. The first 2 pictures are of our little hill, the last 2 pictures is what my wife would like to do.

As always, and and all advice, suggestions, and help are appreciated!

 

[Zeke]

In CA earthquake country (I'm here too and a contractor) you are looking at a massive job anything over 30". Engineering is an absolute must from footing to drainage. There are tons of force on something like a 5 foot wall. Literally tons and not just a couple.

 

[tarmy]

^^^^ What he said.

the soil needs to be examined as well for various features that will determine the wall type, footings, drainage solution, compaction and whatever surface drainage needs to be addressed. You are undermining a neighbor’s property so proceed properly and avoid legal issues as well. I have seen a lot of ******* attempts at retaining earth without proper design…always ends badly.

Also, most jurisdictions around here require an overbuild of upper pads that include about 1-3’ of stabilized (flat) area near the fence line to keep the top of slope from sluffing off and taking the fence with it.

 

[Kurt4440]

A retaining wall of this height will require room behind the face of the wall for either geogrid or a footer.

 

[theoldwizard1]

In CA earthquake country (I'm here too and a contractor) you are looking at a massive job anything over 30". Engineering is an absolute must from footing to drainage. There are tons of force on something like a 5 foot wall. Literally tons and not just a couple.

The 2 most common causes of failures of retaining walls. I will add missing/incorrect tie-backs.

 

[duneslider]

Yes, it can be done but like said, requires engineering and has to be done right. It is NOT cheap to do, not sure what you are thinking budget wise but it can be pretty costly. Might be cheaper to do a shorter tier and still gain some flat space up there?

In my area we can go 4' up without engineering, basically create tiers on a 4'x4' step, anything more than 4' requires engineering. Which is essentially a 45degree slope, which is the max they want to see with just dirt.

 

[oldpops]

Wow, Thanks everybody! Being disabled and on a pretty fixed income, the descriptions of what must be done is no doubt waaaaay beyond our current financial situation. Think we'll just cover the hillside with weed fabric and some gravel stone. But thanks to everyone who offered help!!

 

[FordTruckWench]

A wall of this style might be built with the footer extending back under the hill nearly as far as the wall is tall. This uses the weight of the retained material to keep the wall from tipping over. The OP's existing wall might be built like this - and the setback from the property line is so that the footer doesn't cross the line.