I have a cement walk that is 2' above my driveway. The builder put a small concrete block retaining wall to cover the transition between the heights.

One of the concrete blocks (I have a total of 4, very small wall) has been damaged, and the soil from underneath the walk is coning out.

If I replace the wall with new concrete blocks, do I need to do anything to prepare the back of the wall? Do concrete blocks need to be sealed or something, or are they safe to have direct contact with soil?

The contractor did not fill the voids in the concrete blocks with cement. Is is s smart idea to fill the blocks with cement to stiffen them?

Thanks for your help. I am new to any masonry work.

Rob Walker

There Is No Need To Seal The Back Of The Wall, However I Would Dig Out From The Back Side Of The Wall So You Don't Have Soil Pushing Against Your New Block, As Far As Pouring The Block Full Of Concrete, You Can Most Don't Because Of Money Reasons. If It Was A Foundation Then It Would Be Code To Do So, But This Application Is More For Looks.
If The Block Wall Was Poured Solid To Begin With You Probably Wouldn't Of Had Any Problems To Begin With. As Far As The Wall Leaning Or Cracks
Hope This Helps , Nichols Trim And Carpentry

Retaining walls can be pretty tricky things and no matter how small they may seem, if they're not built right, you can bet that they will fail eventually. I can't imagine building a retaining wall (other than a landscaped cantilever wall in the garden) without a footing beneath it and solid "grout" in the block cells. Concrete blocks don't usually require any special treatment to seal them but they will erode if they are exposed to moving water on a regular basis (even the rockiest mountains are no match for water). I would consider rebuilding the whole wall to make it stable and help to aviod future trouble with the blocks that aren't currently an issue.