Tuesday, August 6, 2013

When pouring a concrete patio, how important is it to lay sand on the soil underneath the concrete?

Q. My installer poured a new patio for me. He leveled the ground, meshed re-bar throughout, and then poured the concrete. I live in midwest where it can get quite cold. Will this hurt anything? Shouldn't he have put a layer of sand or pebble underneath? Can you lay concrete on compacted dry soil?

A. The sand or fine gravel is intended to keep the slab from cracking during the freeze thaw process. You see water expands when frozen which could push up from underneath and crack your expensive investment, the sand or gravel provides drainage so no freezing water is sitting under the concrete. Of course this would be less important in areas that never or rarely freeze, but if your investing a lot of time and expense in somthing it is better to do it right.




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