Backyard swing sets provide children with an enjoyable outdoor activity, but responsible parents will embed a soft, cushioning material under the play structure for safety. This material can protect children from from scrapes, bruises and other injuries when they jump or fall from the equipment. If you visit nearby public parks, you will see that the most commonly used ground-level materials in playground areas are rubber mats, mulch, sand and gravel.
Rubber mats designed for use under swing sets are semi-soft and will not compress, even after years of use. Look for permeable rubber mats to minimize puddling on rainy days, and to keep the surface from becoming slippery. Interlocking rubber mats quickly clip together to enable you to make your play space as large, or small, as necessary. Rubber mats are available in many different colors, which will define the play area.
Natural or Rubber Mulch
A 7 to 11 inch deep bed of mulch can provide a safe, soft landing zone under a swing set. Most local nurseries offer a choice of wood chips or shredded bark mulch in several natural colors. Recycled rubber mulch will last much longer than natural mulch, and is supplied through home improvement centers in a wide variety of colors.
Sand offers a soft cushion if children jump or fall off the swing. For safety sake, you should use fine sand at a depth of 5 and 9 inches. You will need to contain the sand using a border such as lawn edging or timbers. One problem with sand is that it can blow around in strong wind conditions. There's also the lesser risk that kids might come home dirty if they decide to play in the sand. Sand will need to be sifted or raked periodically to remove debris.
Pea gravel in another option for use under swing sets, but only for school-aged children who are no longer tempted to put small items in their mouths. The gravel will allow the water to drain away from the play area, and it will not attract bugs. You should use at least 4 inches of pea gravel to cover the play area.