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Re: Installing Concrete Pavers Over Compacted Gravel or Concrete

From: odyssey2@optonline.net
Category: Concrete
Remote Name: 69.114.19.156
Date: 25 Mar 2006
Time: 06:04 PM

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Question: I live on Long Island NY. What is the proper base for concrete pavers? Should I use a cement (concrete) base or compacted aggregate and sand? I am receiving different opinions on which to use. Thanks, Jeff.

Builders Websource Answer: Typically concrete pavers are set on a base of 1-1/2"+ of washed builders sand (no salt) over a compacted substrate of crushed stone or gravel at least 4" thick. Although the weather in Long Island is more temperate than other parts of New York, in cold climates where the ground may freeze, the stone layer may be as thick as 6" - 8". Always use a filter fabric between the sand and the gravel to help prevent the sand from settling into the gravel. Sometimes we even recommend a filter fabric between the dirt and the gravel to prevent long-term migration of the gravel into the soil. Always compact in lifts a few inches thick using a power tamper. Preparation of the substrate is the single most important insurance to a long-lasting job. However, the drawback to using gravel is that the edge pavers have only the passive side restraint to lock them into place. Many times the edge restraint fails or gets nudged, causing the edge pavers to move out of position which, in turn, causes the other field pavers to begin moving around. This is particularly true on a driveway subject to heavy loads.

However, if you have unstable soil, or you want a rock-solid base, you can also pour a reinforced concrete base. This provides an excellent substrate for adhering all the edge pavers with mortar. Then, the internal pavers are set using sand, just as above. Always set the field (interior) pavers about 1/4" high so that when you vibrate them into place, they will settle to a level consistent with the edge pavers. When we built our home in California, we opted to go with a concrete substrate reinforced with rebar and fiberglass strands for the walkways and patio, and for the driveway edging. This has provided a trouble-free driveway and rear patio/walkway with no settlement in nearly 15 years.  We also compacted thoroughly and used filter fabric to keep the sand and gravel in place. While this method costs more than using only compacted gravel, it will outlast the structure.

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