Is my lawn (grass) ok as a safety surface?
Most climbing frame customers assemble their frame on grass. The impact absorption of grass depends on the soil, and how compact it is. The weather itself will have an effect on the ground ability to absorb impacts.
Officially, according to ROSPA, grass an impact absorbing safety surfacing is considered more than enough for home playground surfaces. RoSPA says that for fall heights under 1500mm (1.5m) grass is a suitable material for use under play equipment.
However, if continued scuffing takes place or a very high traffic area causing soil compaction then alternative surface should potentially be considered. This situation is assuming a minimum 150mm of subsoil, in a temperate climate such as that in the UK where grass grows well will provide a satisfactory level of impact absorption.
Grass Is Cheaper
Yes, as most people already have grass laid in their garden and comparatively with other surfaces buying seed isn't expensive. Maintenance, if you're expecting a lot of use from a frame then a little care may be required this tho is a time thing not maybe a few more seeds to replant an area although left to its own devices grass tends to grow back on its own.
One possibility for areas that are subject to continued scuffing is grass rubber matting that allows grass to grow through it protecting roots stopping the area from going bare and compacting creating a hard area. This matting can be easily fitted with grass growing through in a couple of weeks in season dependent on grass type and conditions.
This article draws heavily on information from an article from ROSPA and the original article can be found here