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I will be installing a concrete paver patio in the near future, and recently dug 6 post holes in the area of the patio and discovered there is about 6" of topsoil/organic material, then a natural sand layer down almost 4 feet.

I am wondering if this sand layer which will be my sub-base (see cross-section below) will cause any issues with the pavers in the long-run, or if it is actually a good thing due to the drainage capacity of sand.

I plan to install the pavers based on this cross-section.

  1. Concrete paver ~2" (50mm)
  2. Polymeric joint sand
  3. Bedding sand 1" (25mm)
  4. Gravel base extended 6" (150mm) past paver extents
  5. Grass
  6. Plastic retaining edge
  7. Landscaping spike
  8. Geotextile
  9. 3/4" crusher run with stone dust
  10. Sand sub-base (pink area) and topsoil above

Installation X-section

I was unable to find any relevant information on the installation of pavers over top a natural sand sub-base, many of the searches returned discuss the bedding sand (3) in the figure above.

Any information would be greatly appreciated.

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Don't use sand for the third layer, ants love it. A new home close to the surface but protected. Use stone dust which is crushed gravel and commonly available at outdoor supply stores.

You can't easily do anything about the sub surface sand layer. A general rule of thumb is that the more effort you put into having a firm compacted base the better the result in the long run. To do this you would:

  • use the biggest heaviest compactor you can get
  • run it multiple times on layers 8, 9 and 10
  • if possible wet the layers or let them get rained on between compaction runs. Water is great for finding less compacted areas
  • compactors are hard to use near the edges, particularly if you are laying this next to any concrete slabs. The extension of the compacted gravel (layer 4) is essential.
  • although a challenge to do having a very slight slope from the centre to the sides so that water runs off is excellent

In addition I recommend the polymeric sand you have in the diagram. Once you use it you will never go back. Keep some on hand to top up areas in the spring.

Observe the current drainage of water. If you have water that is concentrated in the form of rain from swales or runoff from gutters this will remove the polymeric sand and, in the long term, start washing away the base.

Although this is not mentioned in your question be aware that ground continues to subside next to a house foundation even fifty years after it was build. Anywhere the pavers meet the perimeter of a house or concrete slab needs extra compaction and attention to grading.

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  • Thank you for your response, this is all helpful. My follow-up is regarding your first comment about stone dust, I've done a bit of reading and I am finding the opposite opinion (contractor.unilock.com/blog/…). Would you be able to provide a source that shows the pros of stone dust over sand as a bedding layer?
    – rgmrtn
    Apr 20 at 19:00
  • @rgmrtn excellent question, I found all sorts of sites that fell into two categories: stone and gravel suppliers recommend stone dust and interlock manufacturers specify a high grade sand. Some landscapers such as this ardron.ca/2017/12/07/it-is-all-about-the-base recommend sand as the bedding layer and a geotextile under the base if you are on clay. Could you ask whether sand or stone dust is better as a new question?
    – kevinskio
    Apr 21 at 11:53

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