Hi all! My brick walkway just recently started to sag in multiple spots. See where there are some gaps in the brick toward the edge of each step. Any idea what may be causing this? First year in this house so not familiar with all the ins and outs yet. Thank you!
by HollisBrown7
3 Comments
Improper drainiage under the bricks…Water is freezing, expanding, and forcing the bricks out of place.
That sagging is a classic case of base failure and it is almost certainly happening because of water management issues behind those granite risers. When rain or meltwater runs down that slope it hits the back of the solid step and starts eroding the bedding sand underneath the pavers because it has nowhere else to go. Combine that with the freeze-thaw cycle you are obviously dealing with given the snow and the ground heaves up and settles back down unevenly leaving you with those ankle-twisting dips.
You are going to have to pull up the sunken sections to fix this right. Once the bricks are out you need to add crushed stone (not just sand) to bring the grade back up and tamp it down hard until it does not move. I usually recommend using a heavy geotextile fabric under the base in slope situations like this to prevent the soil from migrating further. If you just dump sand in there it will wash out again in six months.
I see this specific failure point on tiered walkways constantly when the installer gets lazy with compaction behind the vertical stone. Gluing the course of pavers directly behind the riser will keep them stable. It is a pain to fix but totally manageable if you are handy.
Though not ideal and technically preventable with proper installation it’s pretty common for pathways with stairs and big stones at the lip. As the water runs down the path it hits the big stones with more resistance and runs across the face of the stone instead of over. That water action starts to erode the base at the edge of the front stone.
Given enough time this happens in most cases of installations like this eventually. The easiest and most practical thing to do is just lift that front layer of pavers and add material underneath every few years.