I'd really like some advice on how to design a new driveway on a steep site - see diagrams.
The drive is 25% nearest the road, then changes to 15% in line with the corner of the garage for the rest of the site, sloping down to the house. There is a french drain across the base of the slope and further drainage to be put in at the front of the house (aco drain). There will also be new guttering on the garage.
Site plan:
https://drive.google.com/file/d/1aaErMm ... drive_link
Photo 1
https://drive.google.com/file/d/1aFARU- ... drive_link
Photo 2
https://drive.google.com/file/d/1EZbu1O ... drive_link
I've been looking at this product:
Core 75-30 - gravel stabiliser
https://www.corelp.co.uk/product/core-c ... tabiliser/
However, in the FAQs it says:
"Can CORE COMMERCIAL be use on areas that are sloped?
Yes! CORE COMMERCIAL grids can be used on driveways that have up to a 20% gradient, which is equivalent to an 11-degree angle or a 1 in 5 fall. If you are planning to use CORE COMMERCIAL on an area that has a steep gradient (15-20%) and it is likely that your vehicle will come to a complete stop whilst still on the gradient it would be prudent to install ‘traction strips’ to allow your vehicle to accelerate on the slope without wheel-spinning and damaging the grid."
I'm now contemplating using this in the 15% gradient area and having an alternative surface at the edge of the road where it's 25%. Vehicles will be coming to a halt in this steeper area because at the boundary between the two gradients I hope to install an automatic gate (hinged both sides, opening down slope), and in order to pull out onto the road.
The area is all on a hill and there can be a lot of surface and ground water, though this doesn't usually spill down the drive except exceptionally we still put in 160mm pipe to take the water away to the nearby river. It is in an area likely to get frozen occasionally in the winter, though I do own snow socks for all the vehicles. The vehicles parking there will be a high top short wheelbase van converted to a camper - weight probably about 2T and a corsa D.
I'd appreciate advice on what options I have here as a surface since significant regrading isn't really possible. Pros and cons would help. The existing concrete on the upper drive is old and not that great- originally I was going to overlay the gravel grids on this. I'm hoping to avoid concrete. I am not sure how to choose between granite cobbles, resin bound, tarmac, block paving. I need to consider cost, but longevity is also important to me. The gravel grids sound like the cheapest way to do the lower drive but I'm reluctant to try to use them outside their spec. The current drive is compacted hardcore to allow site access while we're having our building work done, but I'm converting to a definitive driveway around the summer.