Advice for sloped driveway

[benson]

Hi all. Some expert advice would be much appreciated. Quite similar to the recent post but it looks like ours is a fair bit more sloped in parts.

We are having a driveway constructed, with the following picture hopefully illustrating what we are having done, and the slope. At it's steepest it is around 1:5, possibly a bit more.

[img]https://i.postimg.cc/ygTyxVr....mg]

We had been quoted for permeable marshalls (priora) paving, albeit standard paving of the same style is now being recommended due to appreciating costs but also due to it suggested that it would be advisable to set them rigidly.

We do have drainage in place in between the crossover and start of the driveway, and also at the back retaining wall. A drainage gulley extends all across the back and feeds into 3 soakaway pits under the driveway surface.

Primarily the contractor is concerned about costs. I'd just rather get it done right and I can negotiate if they want a bit extra. Advice would be much appreciated as to what would be best. Drainage and maintenance are our main concerns.

[Tony McC]

Permeable would be more expensive because of the additional excavation and aggregate build-up. However, as a 1:5 gradient, permeable paving would need special provisions to keep it functioning properly, and these would most likely boost costs even more.

You could go for a rigid option, but that, too, is relatively expensive (not as pricey as the permeable, mind) and needs a very high degree of skill to make it look good. There is far more of a challenge in rigid-laying block paving than in putting down a conventional build-up. If you choose this option, make sure you see the same type of work done by your selected contractor previously. I've looked at a few rigid-laid block pavements over the last couple of years and they've been a mess, because the contractor over-reached themselves. I would want to se a fully spec'ed job before giving the go-ahead.

The simplest choice is to rely on intermediate restraining courses, as mentioned in another thread a few days back. These are bands of kerb or blocks laid on concrete and haunched with same running transversely across the pavement to minimise creep down the slope and keep everything in place. There is a little additional cost, but nothing in the scale of your other two options. That would be my preferred option.

[benson]

Thanks Tony. I really appreciate your advice. The intermediate restraining courses make sense. It transpires that I misunderstood what exactly they were proposing to do- they are in fact proposing a concrete sub base and then laying blocks traditionally i.e. not fixed, on top. These proposals will obviously also impact upon drainage. There are 3 soakaway crates installed underneath the drive and my other slight concern is if this is the only drainage solution, there will be debris infill over time as there is no silt trap or similar, as well as the soakaways themselves being inaccessible without digging up most of the drive.

I think we will ask them to stick to the permeable option