Driveway sub base depth

[dosser]

Hi all I'm looking for some advice, I'm in the process of getting quotes for the replacement of my driveway where we keep our 3750kg rated Rapido A class. Not decided on block or tarmac yet just wondering if anyone has any advice on the depth of sub base / type 1 I should be looking to get laid before the finishing layer.
While contractors should be in the know last thing I want is it sinking inches next couple of years.
Thanks.
Kenny.

 

[Googlebot]

At least 150mm minimum.

Make sure you actually check as well, that’s a lot of soil to remove and a lot of sub base to fill and most contractors will try and scrimp on it.

FAQ for Sub-bases

FAQs covering sub-bases, their construction, their necessity and their use in the construction of pavements, driveways and patios

www.pavingexpert.com

 

[Landy Andy]

A lot will depend on what it is going onto, and then what you are planning on finishing it with.

 

[Geistguy]

Whatever the contractor suggests go for a bit more, we invested in 150 mtr "tarmac" drive which has to take the weight of a central heating oil delivery tanker. After 10 years there are no grooves or dipping.

 

[treetops1]

200mm Sub base.Type 1, lime stone, wackered well down ,100mm TARMAC topping or block paving .Have a test dig down to about 300mm if its solid you should be ok with that ,if its soft you may have to dig it out until you get a firm base then bring it up to 300mm below your finished level .chances are if you are rural it may be a bit soft but if on an estate it should be ok with the above.Enjoy lol.

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[Ivory55]

Also remember the edges, decent depth kerbs to stop the spread as well. Sideways movement is important as deep sub base.

 

[dunnah01]

Nowadays I'd use a reinforcing mesh and reduce the dig rather than remove tons of excess spoil to tip.

 

[ctc]

I used ready mix, about 100mm, on top of 100mm rubble. Nothing happened in 30 years and the last few under a 7.5 ton Hymer.

 

[Ivory55]

I think it also makes a difference where you live, if in the fens on peat with all the sunken roads is different to being where it’s solid chalk or rock.

 

[Wagoneer]

It all depends on the surface geology. Your local council should be able to advise the ground conditions for your location. Or go to your local library and ask to see geologlical maps.

A free draining gravel will need less subbase than say a clay substrate. If it's clay you may need to lay a geotextile, like Terram 1000, at the base of the excavation before laying the Type 1 subbase.

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[dosser]

Thanks all great advice will definitely take it on board.
Thanks again.

 

[pappajohn]

When I put the drive and hardstanding for the garage it got 6" to 10" of type 1 and 4" re-enforce concrete. It was on dry clay soil.
Overkill, but I did expect parking my 7500kg RV on it.

 

[DerryW]

100mm type 1 mot aggregate sub base, 1 layer of A142 mesh finished with 150mm C20 concrete.

 

[BouncyBoatFolk]

Make sure you know where all the services to the property are. Some utilities mandate a certain depth for contractors, but don't comply to their own rulings .
Work out the area to dug, multiply the depth x width x length. Roughly double that volume for the amount you will need to cart off site. Do you need a full depth for area's that your never going to drive, or park on?
Are you likely to need any new services shortly, cable, water ect. Best sort that before laying any future finish?
It should be a permeable top layer to allow water to still seep into the ground aquifer.
A membrane will stop fines from settling out, and allowing podgy soft spots.
A good non permanent softer looking finish can be obtained with plastic grids like shown below, filled with your choice of coloured chippings, but it's only one idea.
Mike

 

[jako999]

I don’t know much about this all I can say is ours was dug down around 30cm hard core then a concrete slab reinforced with steel followed by the blocks, it was done around 15 years ago and has had some pretty big A classes parked on it and it’s never moved

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[MattR]

This might help a bit for soils and geology but local conditions vary with history of use and management of the area to be worked on.

Soil: http://www.landis.org.uk/soilscapes/
Geology: https://mapapps.bgs.ac.uk/geologyof...80.1263913819.1616368927-655018794.1616368927

 

[BILL 875]

Planning permission?

 

[Silver-Fox]

Planning permission?

Not with permeable surface

 

[Coastal Cruiser.]

Did the drive in my previous house with 100-125mm of a C40 concrete then block paving on top.
14 years on and still good as new and that had 44ton trucks running over it for 10 months when I was building some houses in the garden

Get the base right and your laughing.

 

[Stoosal]

I would go for 150mm of sub base......if the heaviest vehicle will be under 4ton that should be sufficient.......

As for the surface I would go for crushed gravel. In my experience block paving is a nightmare. Constant weeds and there always seems to be a bit that sinks. Tarmac is good as long as it it not a tight turning circle where you will be doing a lot of manouevering and turning of the front tyres at very low speeds.

Gravel allows water to drain freely whilst with tarmac you will need to consider where rain water will drain to and many local authorities no longer permit hard surface drives etc.

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[Ivory55]

Gravel is a pain. It sticks in shoes and ends up in the car and in the house, cats use as a toilet, weeds love it . I would not have it and I can get it free.

 

[BILL 875]

Block paving as above a nightmare I have it never again.

 

[Stoosal]

Gravel is a pain. It sticks in shoes and ends up in the car and in the house, cats use as a toilet, weeds love it . I would not have it and I can get it free.

Do not know what type of gravel you have but the type I have never sticks in my shoes, never gets in any of my vehicles, as far as I can see is never used as a cat toilet and, apart from the very occasional weed is maintenance free! Maybe it’s a question of the right type of gravel for the purpose it’s being used for....?

 

[BouncyBoatFolk]

Crushed stone is better than gravel, or pea shingle. Stone has odd shaped surfaces that bind to each other, thus holding mostly in place. Gravel and shingle just migrates everywhere, and does invite the local moggies along for a dumping party .
Mike

 

[Ivory55]

Do not know what type of gravel you have but the type I have never sticks in my shoes, never gets in any of my vehicles, as far as I can see is never used as a cat toilet and, apart from the very occasional weed is maintenance free! Maybe it’s a question of the right type of gravel for the purpose it’s being used for....?

I don’t know what type of gravel as we had it replaced by block paving, far more easy to look after.

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[Bessy765]

Not suggesting cutting corners but if you know he approximate area where the van will spend the majority of its time parked, you could alway make that area a bit more robust. Whilst the whole drive should be able to take the weight of the van driving over it. Where it ends up will be the most important area. Ours it 4.5 tons and has sat in the same spot for a long time. Our base where the van is is 150 mm2” to dust compacted topped with 50 mm 803, followed by 150 mm concrete with steel mesh. Over the top but 25 years later unmarked. Remember to allow for the run off of raiiin and where it will go. If you dont drain it away it could undermine one side of your slab.

 

[Ivory55]

Even cars must weigh a bit, because if you look in supermarket car parks the tarmac is always dipped where the wheels go.

 

[Nasus]

Block paving as above a nightmare I have it never again.

Why never again?

 

[BILL 875]

You always get weeds and if you power wash it later you get double weeds. Bill

 

[buzz1]

Some good advice above.
I would depending what you have down on driveway at the moment , dig half driveway up then remove at least 100mm off sub soil,
then back fill with your old driveway material / hardcore .
then do same to the other half of driveway, once all hard core down Wacker plate whole area , then lay geotext free draining type on top of hardcore.
then top off with a good quality type1 (mot) 100mm depth
then Wacker plate down again, making sure you have correct fall away from house to a drain area if possible.
then lay 16mm - 20mm gravel to 40mm depth .
depending on your access wheel barrow all dug out soil to area of front of driveway
then get a grab lorry to remove , much cheaper than skips .
worth doing yourself and cheaper. Get a good matock better than a pick ideal for dig soil.
good luck .