We are reclaiming a flower bed and extending our existing patio. After a gully washer I am now concerned about drainage for this 5ft by 36ft impervious surface we are adding. We are also adding a stair case in the middle to access the upper yard over a brick retaining wall. The stair case will be 2 risers and end where the retaining wall brick drops off 4 feet wide stairs. For relation each existing concrete square is 2ft by 2ft enter image description here

So my question is how would you drain? Can I run pvc pipe under the stair case to allow draining under the stairs? Should I drin towards retaining wall and away from house and existing patio? Should I drain towards existing patio and add a channel? The next problem is what to do with the water once it gets to the end of the patio? enter image description here Just add a French drain along the length of new concrete and funnel to flower bed? Any help would be great. Mainly wondering about the possibility of running pvc under stair case to allow drainage and not ruin concrete integrity. Thanks in advance.

  • 2
    All that really comes down to where you want the water to go. Why is that a question for the internet? You might want to revise to ask something more specific, such as about technique, rather than location. It's very hard to say without having a neighborhood site diagram.
    – isherwood
    Mar 29, 2021 at 13:54

1 Answer 1


The direction of drain should be from the house toward the end of patio. I'll consider to provide French drain along the retaining wall, then discharge to storm water system, or a sandy pit in your own yard.

  • Ok how about the pvc pipe under the concrete staircase to allow for drainage. Any issues with that?? Mar 29, 2021 at 16:53
  • I don't see problem there, if the PVC pipe is surrounded by well compacted soil, that is capable of supporting the concrete steps without excessive settlement. Note, if the pipe is much deeper that the bottom of the stair, you should place 2"-3" sand over it. Another way is place the PVC pipe in a trench (a few inches wider and deeper than the pipe) and wrap the pipe with concrete. I'll use X-strong pipe under the stair though.
    – r13
    Mar 29, 2021 at 17:45
  • One more precaution - watch out for frost heave. For live in the cold region, you should consult with a gardener/contractor, who is experienced on lawn sprinkler installation
    – r13
    Mar 29, 2021 at 20:17
  • Thank you. I shall proceed as planned. Mar 29, 2021 at 23:38
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    @AdamJenkins if you'll take the tour, you'll note that the proper way to say "thank you" is not with a comment, but by clicking the up arrow next to an answer that helps you, and the check mark next to the answer that helps you the most. That also helps others to know that a particular question has a good answer that resolved it.
    – FreeMan
    Apr 28, 2021 at 15:12

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