Paving layer depth - 60 -70mm deep

[clintpm]

My neighbour and I are in the process of building adjoining drives. Total area 100 sq metres.

We are using 50 mm block paviers (already bought).

The sub-base is down and compacted (using a bl**dy big Whacker) and the edge courses (includes one which separates the 2 drives) are concreted in.

We have just measusured the distance from the edging tops to the sub-base (110 to 120mm) and have realised we got the depths messed up. Should be 100mm max.
This will give us a finished sharp sand laying depth of 60 to 70mm.

I have read through the forum and have come across comments about desasterous drives which were laid on sharp sand thicknesses of 100mm upwards.

We are only just over 50mm and I am hoping we will get away with it, knowing we have maximum sub-base compaction and if we ensure total compaction of the sharp sand. We really dont want to add more type 1, level and re-compact.

Opinions please!!!!

[Bob_A]

Hiya mate sorry I can't give any real answers as I'm here to learn as well but I'm curious why you don't want to add more type1. If you're not sure about sand thickness wouldn't it be better not taking chances on a thick layer of sand.
I think I'm right in saying that after reading one of Tony's, posts that after years of experience the trade has come to the conclusion that the preferred layer of sharp sand has been reduced to something like 25-40mm.
Perhaps someone could correct me if I'm wrong on that.


Edit
Found on this post
http://ext.pavingexpert.com/cgi-bin....ony+mcc
We've 30 years of experience using flexible block paving in this country as of this year. Over those three decades, we've gradually refined the laying advice in the light of experience and extensive research: the 2005 update saw the recommended laying course depth reduced from 35-50mm to 25-40mm because it had been shown that a slightly thinner laying course resulted in less settlement. This is research prompted by experience on site and then validated by extensive professional and accredited testing at dedicated research facilities. The result of all this is that we have, in Britain, probably the best laying advice of any nation.

[clintpm]

Thanks Bob
I was just trying to avoid a lot of work.
Sounds like there's no way of getting away from it.

[lutonlagerlout]

add more stone and recompact
70mm is way too much sand
btw your link is down
LLL

[Rich H]

Works for me but none of the pictures are actually on the site (perhaps on a pc instead).