Joined: July 2004
||Posted: 13 July 2016,09:58
You will have a huge problem trying to place a laying course of 6/3 clean over a Type 3 sub-base. It will just disappear into the ample void space of the Type 3, leaving you with no laying course and a clogged-up sub-base.
There are two solutions:
1 - graduate the laying course, so that you have, say, 50mm of 20/5 over the Type 3 then 25-30mm of the 6/3. Then 20/5 will not settles as far into the Type 3, and then forms a sound layer for the 6/3
2 - use a decent geo-textile (TDP115/Terram/BuildA or similar) over the Type 3 before placing the 6/3
With this form of construction, there simply won't be any "excess water", so no real need for a fall. Constructed properly, there should be no issues with damp, but if you want to adopt a belt'n'braces approach, you could tank the sub-DPC bwk with bitumen or line it with a waffle board.
As for a 'traditional gravel look', that very much depends on where you live. Here in South Lancashire, it would be limestone chips, gritsone chips or Cheshire pink river gravel. In that London, as discussed in another thread this week, it would be that bloody hoggin!
Site Agent - Pavingexpert