Driveway Retaining Wall Above Ground

[LimitedReality]

After almost a year of going back and forth with my township over where and how I could build, we've finally gotten started on my garage build. The only problem is, now that we have the block foundation in, I am starting to wonder if the mason passed on quoting the driveway wall and instead suggested I could do it myself because of the logistics of it. Maybe I'm over thinking it so I'm looking for advice.

The only place that I was allowed to build is on a fairly decent slope (see drawing below). This causes the drive coming up to the garage door to need to be built up about 5" on the right side and 2.5' on the left. From researching online this kind of low retaining wall would normally be either:

1. Dug down one block deeper than ground level and using interlocking retaining wall block to stack up from there.
2. Be dug below the frost line and built on a proper footer like the foundation.

The challenge with either of these ideas is I had to squeeze the drive in between two mature trees that we really don't want to take down (we bought the place for the beautiful trees). So I can't dig down so close to the trees as I'd take out their root system.

I'm wondering if anyone has done a similar retaining wall without a footer? Without digging down? I may be able to drive rebar safely into the ground every other block to pin it in place, but I worry about the longevity of that rusting out and giving way. Again from reading it seems like there won't be a ton of outward pressure on the drive since the majority of the load will be in the center. I plan to keep my motorcycles on the outside edges and a truck in the center.

Thoughts?

 

[Orionrising]

2.5 feet is significant. easiest may be using concrete waste blocks.

 

[theoldwizard1]

I'm wondering if anyone has done a similar retaining wall without a footer? Without digging down?

It will not hold without a footer and for 2-3' high wall, you want to be down t the frost line.

 

[JimR1998]

Depending on how you're disturbing the site, the trees may die or decline just because you're covering their roots with your new driveway and compacting the ground around them.

Easiest is probably a boulder wall, which may still crush the tree roots. There are lots of options. I'd probably get a large load of rip-rap size boulders on the sides and infill with 1" stone to pave on.

 

[machsnell]

You are going.to be filling on the trees roots so close that you dont want to dig down for a proper footing?

Got any pics or plan view?

Filling on root system is not certain death but will push a tree into decline and a slow death.

If you are far enough away then a keystone block wall will be supported by grid tie backs. You still want at least one course of block below grade though.


Layout would help

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[machsnell]

Depending on how you're disturbing the site, the trees may die or decline just because you're covering their roots with your new driveway and compacting the ground around them.

Easiest is probably a boulder wall, which may still crush the tree roots. There are lots of options. I'd probably get a large load of rip-rap size boulders on the sides and infill with 1" stone to pave on.

Great minds.....

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[garagelogician]

If using a concrete modular block, there shouldn't be any need do dig down below the frost line unless you have extremely clayey soils. Are you going to do a concrete driveway or asphalt?

Does the toe slope in front of the wall continue at the same grade you have shown on your sketch (about 7.9 degrees)? Minimum embedment (crudely) at that slope should be at least 8" plus 1" for every foot of wall height. If it gets steeper, you will need additional embedment. The wall will need to sit on a 6" thick aggregate/crushed stone leveling pad, so at a minimum you will have to excavate down at least 17" (or more depending on how deep the topsoil/organics are).

I wouldn't mess with rebar into the ground or anything like that. Its not used for precisely the reasons you mentioned, among others.

Pictures and a plan view layout would be very helpful. Contact a block manufacturer in your area and see if they can give you a preliminary plan and quote for materials. In our office, we'd probably charge about $250 for a prelim and maybe $1250 for a final (though you probably wouldn't need stamped plans for a wall less than 4-ft.)