Astroturf. is mot type 1 permeable?

[KAMIKAZEE DIY]

Thinking of installing a small area of astroturf. Area is flat. Concerned about the recommendations to lay astroturf on compacted sharp sand above compacted type 1. Can water drain through this?

[dig dug dan]

No. Best lay on crushed, blind it with grano dust. Not sand
Or dont lay the stuff at all, consider the environment!,

[Tony McC]

Comp[acted TRype 1 is just about permeable. It all depends on where the line is drawn between what we consider 'permeable enough' and not sufficiently permeable. For something like placky grass, compacted type 1 is regarded as 'permeable enough' because it's coefficient of permeability is similar to that of many soils.

However, for a dedicated permable surfacing, notably concrete block permeable paving (CBPP) and some permeable macadams and resin bound surfaces, a Type 3 agregate sub-base is required to ensure there is no flooding at times of storm conditions.

This issue of "how permeable does it need to be" is becoming an ever-bigger problem because of the growth in popularity of resin bound surfaces. many installers (and too many suppliers) are claiming a Type 1 sub-base will be adequate, but the top installers/suppliers are increasingly opting for a Type 3 aggregate sub-base to ensure adequate permeability.