I'm building a 3'-4' retaining wall in my backyard and I'm in the process of choosing block. One of the blocks I like isn't engineered with any kind of lip or interlocking feature. Is this necessary for a wall that size? Or is this type of block meant more for a freestanding wall or a small garden wall with only 2-4 courses?
Concrete – Should a 3′-4′ retaining wall have interlocking blocks
concrete-blocklandscapingretaining-wall
Related Solutions
The engineering on such a wall may prove difficult. We recently built a 6' retaining wall and a couple of 5' retaining walls. The 6' wall was 32 MPA concrete spray using our pool as the footing, the 5' walls are steel reinforced, core-filled besser blocks with footings 600mm deep and 1000m wide. In both cases, using steel and concrete, the engineering was complex. We rendered both walls. We constructed our walls this way to minimise the foot print (the walls are 200mm thick).
Using something like boulders could prove tricky unless you have a 45 degree angle of repose - this would simplify things but also eat up a lot of your back yard.
My neighbour has just build a shorter retaining wall with besser blocks then added a rock finish afterwards - looks rather nice.
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:
Related Topic
- Retaining wall: footing or no footing
- How to finish retaining wall for a paver patio on a sloping ground
- Can solid offset blocks be used to build a retaining wall in excess of 5′
- Walls – fill cinder blocks with soil/dirt
- Concrete – Should I build a segmental retaining wall on top of a grade beam with piles
- How to properly allow for drainage for a backyard retaining wall
- Electrical – run conduit through a retaining wall
- Walls – Footing required for a low garden wall
Best Answer
The blocks you linked to are more for decorative purposes; one or two courses around flowerbeds or trees. What you're going to need for 3'-4' of retaining wall is something like this:
This is engineered block from http://www.anchorwall.com (I'm not affiliated; it was the first thing that came up when I Googled "Retaining wall blocks"). As you can see, they (and most other providers) can put that "hand-chiseled" look on just about any type of manufactured stone, and color it to your liking, so you should be able to get pretty close.
Understand that a wall like the one in the picture will probably run you between 15 and 20 grand, installed. On top of the blocks and the labor, there is a LOT of prep work that goes into building a wall like this. You have to consider grade on both sides of the finished wall, water drainage (water will sink into the soil and collect behind the wall), as well as build a proper foundation beneath grade (this particular wall represents maybe about 20 TONS of stone, so it needs a very solid base of compacted crushed gravel to prevent shifting and sinking). And yes, you need all of this, because if this wall moves, the soil behind it moves, and then whatever that soil is supporting (like your house) will move.