What permeable paving options are available?

Several permeable paving options are available- from inexpensive loose gravel. Grid systems, block paving, porous asphalt , resin bound paving and rubber- resin systems. All have their all have plus and minus points. Although relatively inexpensive, stone can migrate from loose gravel and grid systems and be difficult to walk on in heels. Block paving requires regular maintenance and periodically dressing with sand . Resin bound gravel is installed  over concrete or tarmac. This causes problems when water travels through the permeable 20mm surface and traps between the concrete or tarmac. As water freezes it expands and this can cause cracking and delamination. A period of at least six weeks must be left before resin is installed onto tarmac to allow natural oils to dissipate. A regular resin surface  must be  treated with frost in frosty weather and cleaned immediately afterwards. Asphalt or open textured macadum  is prone to has no flexibility and clogs over time.