300mm sub-base thickness?

[LeadFarmer]

Ive obtained a few quotes to block pave my driveway. Each have specified a different MOT1 sub-base thickness ranging from 100mm to 300mm.

Is there any advantage to having a 300mm base? Can a sub-base be too thick, or is it a case of thicker the bettter? My car is quite heavy at 2500kg.

Thanks

[Dave_L]

A 200mm subase for normal (4x4) traffic on a residential driveway is more than adequate aslong as the ground is firm at the bottom of the dig.

[Carberry]

Wouldn't go any less than 150mm if you have a heavy vehicle.
If you are going above 150 compact it in 2 parts ie: lay and compact 150mm, lay and compact another 150mm to make a total of 300mm.

[lutonlagerlout]

^^ what they said
also using a non woven geotextile is a massive upgrade
this stops any migration between the sub base and the type 1

TBh i have never seen 300mm of sub base on a domestic drive and would question why he has specified it so thick?
LLL

[rab1]

thinking the same thing but with farmer in the op name tag, was thinking what else could run up this drive.

[Big Phil]

subgrade must be really poor if they recommend 300mm for a private drive. on larger jobs you can get away with a capping layer of cheaper material, then top off with subbase but for driveways it may be less mither just to double up.

[haggistini]

Have they broke ground? This would decide the depth required of sub-base.
But I would expect 150mm minimum.

[seanandruby]

if it's just your ''heavy car'' then 150 should be fine, raising it to 225 if your expecting heavier traffic.

[LeadFarmer]

thinking the same thing but with farmer in the op name tag, was thinking what else could run up this drive.

No, im not a farmer.

Work hasnt started yet, my current concrete drive is still in place. But Im on very heavy clay, I dug a test hole in my front garden once and I got 1200mm deep and it was still clay!!

The firm quoting 300mm has done driveways in my area and knows about the clay. Would the clay be a reason for such a thick base?

[lutonlagerlout]

dont really know why they would quote for 300mm
make sure its type 1 crushed limestone they are talking and not "crusher run"
thing is do they mean 300mm dig? then 200mm subbase and 40 mm sand and 60 mm block?
problem with going overly deep is that you tend to start hitting services and sewer pipes
which are expensive to fix
LLL

[haggistini]

I like crusher run if it's good quality size 40mm-dust. Reason being I have had block drives lift last winter ( my mothers!) and the sub base was spot on type 1 and had no problems with the drives I had used crusher run on???

[lutonlagerlout]

hmmm
thing is hagg they all promise you the finest of crush ,then it turns up and its the leftovers from a landscapers skip
had it twice now so never again
thing the drive lifting would have been heave rather than the type 1
LLL

[haggistini]

Thats what I meant , but is it as good or not!