Sand

Sharp sand — also called concrete sand or bedding sand — has angular grains of mixed size. Those angles lock together under load, which is what makes it the correct bedding layer under pavers, flagstone and above-ground pools.

Mason sand is finer and more uniform, with rounded grains. It mixes smoothly into mortar, sweeps nicely into paver joints and makes a comfortable base for a sandbox or a volleyball court. Use it under pavers and the surface will rut, because rounded grains roll past each other rather than interlocking.

If you are unsure, tell us the job rather than the product name and we will load the right one.

A paver bedding layer should be one inch of sharp sand, screeded level, over a compacted base of crushed concrete or limestone. More sand is not better: a thick bedding layer behaves like a cushion and lets pavers migrate.

Screed with two lengths of one inch conduit as rails and a straight two-by-four as the strike board. Pull the rails as you go and fill the channels by hand. Do not walk on a screeded bed.

Washed sharp sand is a good drainage medium because the silt has been rinsed out. Silty sand packs into something close to concrete when it dries, which is why bank-run material is a poor substitute in French drains and dry wells.

For heavy clay yards that pond, a sand-and-loam blend worked into the top four inches will do more for infiltration than sand alone laid on top.