Sources and Methodology

This page lists the main types of source behind our guides and explains how our own models work. Individual guides name the specific standard, agency or document where a claim depends on it.

Standards

Standard	What it covers	Where we use it
ASTM F1292	Impact attenuation of surfacing within playground use zones; defines critical fall height using head injury criterion (HIC) and g-max thresholds	Fall height and shock pads
ASTM F1951	Accessibility of surface systems under and around playground equipment	Turf vs mulch and rubber
ASTM F1936	Impact attenuation (g-max) of turf playing systems as measured in the field, used for American football fields	Sports fields
ASTM F355	Laboratory method for impact attenuation of playing surface systems	Shock pads
FIFA Quality Programme for Football Turf	Lab and field performance and durability testing for football (soccer) surfaces	Sports fields
USGA Stimpmeter procedure	Measuring green speed	Green speed and the Stimpmeter

Government and agency guidance

U.S. Consumer Product Safety Commission (CPSC): the Public Playground Safety Handbook, for use zones, surfacing guidance and loose-fill depths. cpsc.gov
U.S. EPA WaterSense: residential and landscape water use context. epa.gov/watersense
U.S. federal research on recycled tire crumb rubber (EPA, CDC/ATSDR and CPSC): the multi-agency research action plan started in 2016, used for the status of crumb rubber exposure research.
European Union restriction on intentionally added microplastics (Regulation (EU) 2023/2055): including the transition period for granular infill on synthetic sports surfaces.
State and local water agencies and municipalities: for landscape rules, turf replacement programs and restrictions. These change often, so our state guides describe policy at a general level and tell readers what to verify locally.
Utility locating (811): for excavation safety.

Manufacturer and industry documentation

Product specification sheets, installation manuals and warranty documents from turf, infill, shock pad, adhesive and edging manufacturers are our main source for typical specification ranges (face weight, stitch rate, pile height, backing types, drainage rates, recommended infill rates). We use them to establish ranges and norms, not to rank products. Industry association guidance on installation and maintenance practice is used in the same way.

Research literature

For heat, health and environmental questions we rely on peer-reviewed studies and public health reviews, and we describe the overall weight of evidence rather than citing single results in isolation. Where findings are mixed or research is ongoing, guides say so.

Our models

Several pages and all calculators rely on models we built. Each is documented on its own page:

Cost: 2026 turf cost index. Built from typical published material prices (turf, aggregate base, infill, edging, seam supplies), equipment rental rates and labor productivity, with size and regional adjustments. It is a model, not a survey of quotes, and is used by the turf cost calculator.
Water: water savings by city. Annual reference evapotranspiration times a crop coefficient, minus effective rainfall, divided by irrigation efficiency. Inputs are rounded long-term approximations. Used by the water savings calculator.
Total cost of ownership: turf vs grass cost over time. Flat-dollar cumulative cost with replacement, used by the turf vs grass calculator.
Lifespan: lifespan model. A baseline life adjusted by use intensity, UV exposure, fiber, product tier and maintenance.
Heat: surface temperature data. A synthesis of published field measurements, expressed as typical ranges.

How we keep figures current

Cost figures and state guides are reviewed most often, because prices and local rules change fastest. Technical guides are reviewed when standards or common product specifications change. Each page shows its last update date, and substantive corrections are logged on our corrections page.