New Tarmac over existing old tarmac

[McD1978]

Hi All,

I'm getting new tarmac put down over existing tarmac. The old tarmac driveway has been in place for about 20 years and is in a bad state.
I've brushed and powerwashed the old driveway a number of times but I still have small bit of stubburn moss that I can't get out. Also have a small bit of fine dust thats lying on the old surface thats doesn't seem to want to move despite the powerwashing and brushing.
Will it be okay to put the new tarmac over this or will the fact that there's a small bit of moss and dust on the old surface cause a problem?

 

[Sue Ellen]

You could try having a read of www.pavingexpert.com to see if that can give you any advice.

Would have thought though that the old faulty driveway would need to be removed and start with a perfect blank canvas.