Retaining Wall Drainage: Weep Holes, Backfill and Why Walls Fail
Ask me what kills more retaining walls than anything else and I won't say bad brickwork or the wrong material. I'll say water, specifically water that's been given nowhere to go. In the guide to garden retaining walls I wrote for this site, I said drainage is the single biggest cause of failure, by some distance. This is the piece that explains exactly how proper drainage is done, because it's the part almost nobody sees and almost everybody underestimates.
None of what follows is complicated in principle. It's a handful of components working together: an opening in the face of the wall, a layer of stone behind it, a pipe at the base, and a fabric that keeps the two apart. Skip any one of them and the system stops working, often quietly, for years, before it doesn't.
Below, I'll cover what each part does, why the layer nobody sees matters more than the wall itself, why Kent clay makes the job harder on both counts, and what to do if you suspect an existing wall's drainage has already failed.














































































































