Advice on driveway

[nabby68]

Hello
I would like some advice on my front garden.
I plan to open up my existing garden to make onto a driveway for two cars.
How deep would my sub base have to be because I've read conflicting advice. Some say 100-150mm others say 200-230mm?
Also any ideas for a suitable finish. Ive tried to attach an image of the existing garden but I'm not sure its worked1
Many Thanks

[doobin]

A lot depends upon your underlying soil and drainage conditions. If you are dry and sandy, towards the lower end of the scale. Wet and cly, then more sub base.

Don't underestimate the importance of a membrane also- its gotta be worth at least 50mm of sub base in my book. Think of how they lay roads through peat bogs for giant cranes- just tonnes of stone on top of a heavy duty membrane.

[Tony McC]

The required depth of a sub-base is determined by the load bearing capability of the ground beneath, the sub-grade. This is known as the CBR - California Bearing Ratio. This is a number that can then be used to calculate the *minimum* depth of a sub-base required to carry a known type/quantity of traffic.

For the vast majority (but NOT all) driveways in Britain and Ireland, it will be somewhere in the region of 100-150mm *minimum* compacted depth.

200mm is great. 230mm is even better, but there comes a point where you are just wasting money and aggregates. For most driveways, that point is around 125mm.

[nabby68]

Thanks Tony, great reply. I was also looking for some advice on what to have as a finish. I like some block paving, mainly the larger sizes such as 100x100 squares but im a bit put off by how much maintenance it would take to keep weed free. Ive also seen a driveway with just basic 600x600 concrete slabs with a block decorative border. Am I right on saying it would be preferable to lay the flags on a wet bed and the block on a screened bed?
Thanks

[Tony McC]

It's up to the installer - some would do as you suggest; other will lay everything on a screeded bed of semi-dry; some will lay everything on wet mortar.

It's not that one method is better than another - it's a matter of what works best for the installer to achieve the perfect result.

[Tony McC]

Forgot to mention..... properly maintained block paving is no more difficult to manage than any other surface. The problems arise when block paving is denied the essential maintenance, and, due to the amount of jointage per square metre, it can start to look far worse than an equivalent square metre of, say, flags, blacktop, resin or whatever, even though the required maintenace for al those surfaces is essentially identical.

I have 90-odd square metres of block paving to my driveway. I spend around 20 minutes per year on maintenance - https://www.pavingexpert.com/maintain_04 - and it looks as good as it did when first laid 20...errr....26 years ago, it is now!

[nabby68]

Thanks again Tony for the reply. I think I've decided to go with basic 600x600 concrete flags also framing it some way with setts or cobbles.
Any advice on do's and don'ts with concrete flags appreciated. Also is there a top end and lower end of concrete flag or are they broadly the same quality?
Thanks

[Tony McC]

The BS flags (council flags) are all manufactured to a standard (hence the name!) and there's little to choose between them. None are manufactured for their good looks - they are purely functional.

More here: - https://www.pavingexpert.com/pccflag1

[nabby68]

Thanks again Tony. Can you recommend a stockist of these that will maybe have a good selection and variety of sizes to look at. Im in Rainhill, not far from Warrington if that helps?
Thanks

[dig dug dan]

Any decent builders merchants will stock these, they are an industry standard item

[Tony McC]

Chris, at Landscape World in Widnes - you'll struggle to find a more helpful stockist - https://www.pavingexpert.com/landscapeworld_01

[nabby68]

Hi, just another quick question on the sub base for my driveway. Am I correct in saying the sub base should consist of compacted Type 1 MOT then a concrete base and then the finish level laid on a full mortar bed?
Also, is recycled mot ok for a driveway?
Thanks

[Tony McC]

A sub-base should be a Type 1 aggregate, either primary agg or recycled, as long as it's a Type 1 (the correct name for "MOT" since 1972!)

A concrete base is a ....well, a base, not a sub-base, and it may require a sub-base beneath it.

There's nothing structurally wrong in laying over a concrete bed using a mortar bed, if that's what you want, but it's more costly and can take a bit longer.