There are three types of face yarns in the synthetic grass industry. Face yarn refers to the yarn one sees on top, and thus exposed to traffic. These types are texturized, primarily used in indoor gyms and field turfs, or on putting only golf greens. Monofilament is the prettiest yarn and used for landscape applications or areas where aesthetics takes precedence over function. Finally, there is slit film, which is made for high-traffic spaces. Slit film can stand back up and fight gravity better than monofilament.
One may find an NFL field or two using the prettier monofilament yarns, but these get resurfaced much faster than other municipal applications and are only used a few times per year. Almost all sports fields use slit-film and there is no reason why playgrounds should not do the same. If a church or a school wants a beautiful, low-maintenance lawn by the front door, it should install a monofilament landscape product. Lawns around multi-family properties, senior housing facilities, office complexes, or retail outlets where looks trump utility, choose the prettier turf, but for high-traffic playgrounds, it is better to install slit film yarn.
The other consideration when it comes to playgrounds is impact zones. Every playground equipment manufacturing and installation company specifies a safety zone and fall rating based on the size and height of the design. Synthetic grass utilizes padding below the turf to satisfy fall height and safety impact requirements on playgrounds. Many types of padding from many companies exist for this purpose. The fall height testing data from the padding manufacturer combined with the requirements from the playground equipment manufacturer determines the exact product requirements and the exact area to be covered for the safety surface.
Base settling in high traffic areas can create maintenance issues, but can also be addressed during installation. Normally, a 101.6-mm (4-in.) base is installed to provide stability of the lawn. When designing areas under swing sets or at the bottom of a slide or ladder, where children are impacting the surface hundreds of times per day, installing a thicker base, up to 254 mm (10 in.), in these areas can help reduce any settling which may occur. If these areas do settle over time, they can be raised by removing the problem section of turf and padding, adding base material to level the grade, and then replacing the turf and padding. Specifying an extra 18.6 to 27.9 m2 (200 to 300 sf)—just a 1.4 to 1.9 m (15 to 20 ft) roll—of matching turf be set aside and kept on the property is wise, should the need ever arise.
Quick hits on other surfaces
Bocce ball courts need a thicker base—sand-filled turf at least 38 mm (1.5 in.) tall—so if the player ever throws a lob shot, the surface will not be dented. If texturized yarn is specified, the surface may roll too fast if the court is less than regulation length of 27.4 m (90 ft). In this game, if a ball is rolled and hits the far end without touching another ball, it is deemed out of play. Therefore, installing a surface which is too fast will deliver terrible results. The biggest mistake is installing texturized turf rather than monofilament with the proper sand fill if the size of the court is too small.
When it comes to croquet, turf must be based on court size. If the surface is too fast, the players will not use it very often; therefore, proper speed is the goal. A 1417 or 1700 g turf is necessary to provide enough friction to slow down the balls. The amount and size of sand fill will determine the speed of the roll. This sand fill can be altered and adjusted both in the beginning and during the lifecycle to deliver desired speeds. If the surface is too fast for the size of the court, nothing can be done other than replacing the turf. Further, it helps if the base is laser leveled to ensure a proper playing surface. From the author’s experience with the U.S. Croquet Association and its board, having a surface that is too soft and bouncy will not allow for the necessary jump shots that are a strategic part of the game.
Synthetic golf greens
When it comes to surfacing golf greens, the key is knowing if it will be used for putting only or if the player has space (and a desire) to hit a golf shot into the green. Synthetic grass golf greens, not to be confused with putting greens, need to have a slim-fit turf at least 25.4 mm (1 in.) in height, capable of holding 39 kg (8 lb) of sand per 0.09 m2 (1 sf). Installing an impact pad between the turf and the sub-base is necessary so, after four to five, the green will continue to hold a golf ball, just like a natural grass golf green. Properly designed and installed synthetic grass golf greens can be just as good as their natural grass counterparts without all the maintenance, agronomy expertise, and expensive equipment. The weak links include poor design, due to a lack of golf knowledge; a poorly constructed, bumpy base; and choosing a putting-only golf turf when trying to hit a shot into the surface.
Permeability and erosion
Synthetic grass has a high drainage rate, making it the ideal solution for projects in an area or municipality focused on mitigating run off and erosion. Synthetic grass can easily become 100 percent permeable. Typical installs would use 101.6 mm (4 in.) of a crushed stone aggregate compacted to create a very durable sub-surface. On top of the aggregate to create a smooth base is 12.7 mm (0.5 in.) of dust from the aggregate, which is similar to a paver base.
If permeability and the flow of water is of high concern, a different sub-surface can be created from stone such as the size 57 stone. These stones are about 25.4 mm (1 in.) and come in various shapes to create voids for water to flow. Using landscape fabric to separate the 57 stone from the dust layer is one way to keep the layers separate, but not totally necessary. Using 25.4 mm of dust on top of compacted 57 stone is usually all it takes. Water will flow directly through the turf and this porous base into the soil below.
Erosion is a big issue in many locations out west, where dry climates have very loose soils. Lake Tahoe is one example where construction is limited during a large portion of the year to prevent unnecessary erosion, which can cause landslides and problems for many construction sites where land has been disturbed. By installing synthetic grass where a sub-surface of 101.6 mm and then 38 to 50.8 mm (1.5 to 2 in.) tall turf filled partially with infill is installed, erosion concerns can be alleviated. Turf can slow down the flow of water and the compacted sub-surface base is stable. Eliminating weak links on construction sites of run off and erosion both can be solved with proper synthetic grass design and installation.