U.S. baseline
The U.S. Access Board's ADA guidance states that accessible floor and ground surfaces must be stable, firm and slip resistant.
Carpet
ADA standards also include provisions for carpet or carpet tile on accessible routes, including secure attachment and pile requirements.
Changes in level
Thresholds and changes in level are regulated separately from general surface characteristics.
International projects
Other countries use their own accessibility legislation and standards, so U.S. ADA rules should not be exported as universal requirements.
Commercial flooring decisions depend on the actual substrate, moisture conditions, traffic, cleaning regime, accessibility requirements, fire/building rules, manufacturer instructions and local code. This site is for planning and comparison, not installation instructions.