Sand over/near French drain?

Old 11-05-22, 09:14 AM
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Sand over/near French drain?

Hi all. I wrote earlier in this week about an uneven brick patio that seemed to have 3/4" gravel under the bricks.

I did some digging and learned that there is a French drain under my patio...hence the gravel. The rest is sand over gravel as it should be.

The brick pavers use a running pattern parallel to the perforated black flex drain pipe.

I presume perforated pipe French drains hate sand (true?) and I know brick patios love sand.

Question 1: Can I get the sand any closer to the drain to make the brick leveling easier? I think the gravel bed is about 16-20" wide.

Question 2: The point of greatest subsidence was over that drain inlet. Is that supposed to be over a very slightly angled bowl in the bricks? Wondering if that makes a difference. It does seem, after 25 years, that there is not much of a bowl leading down toward it.


You can see the perforated drain pipe, with a cleanout/drain at the lower center.

Last edited by debeze; 11-05-22 at 09:16 AM. Reason: edits for clarity
Old 11-05-22, 10:32 AM
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1. I would put down landscape fabric between the compacted gravel and sand layer. It will still allow water to penetrate while holding the sand in place.

2. If there was not an intake grate/drain on the surface I doubt they did it intentionally. The dip you have is more likely a mini sink hole. Sand, dirt may have been washed away over time causing the area to sink. If the drain in your photo is in the area they might have tried sloping toward the drain and didn't do a good job. If you want to do that I'd go out as far as you can/want and set up guides to screed your sand with a slope towards the drain.
debeze voted this post useful.

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