Concrete driveway over existing potholed and old tar and chip driveway

choppermutt

I need to do something with my tar and chip drive. Its been down 15 years and half the tar has weathered and worn away. Once I've cleaned it up and got rid of all the loose stone can I pour a new concrete drive over the existing tar/chip with no other preparation to the old surface? No really bad potholes.

MarkR

Wouldn't you wind up having a raised driveway then? 10 cm (guess) of concrete on top of the existing tarmac. I'm a computer nerd and know nothing about driveways, but the height would concern me.

choppermutt

4 inch rise.…..doesnt bother me. I can ramp it down at one end.

naughtysmurf

I’ve seen a lot of concrete driveways put in in my area over the last few years including our own & not one of them laid it on top of the old tarmac driveway, all were dug out, must be a reason for it, maybe it is just height, would be a shame if it didn’t work out aesthetically & also from a longevity perspective

monseiur

Concrete will not adhere to tarmacadam and will crack and rise over time. Best to dig it out add tow inches of clause 804 blinding and compact with whacker plate or vibrating roller (depending on area)

893bet

how would the 4 inches of concrete work up towards the house/footpaths?

mickdw

If its a loose stone drive laid over hard-pressed, that should be a suitable base for concreting after a basic scraping back to a reasonably flat surface.

If however you have tar and chip laid on God knows what, take it up before concreting.

The levels are critical though so if you have existing kerbs, gates etc, you are snookered and will need to reduce ground levels. You will need to reduce ground adjacent to house anyway.

Do not allow anyone to attempt to raise path level as an easy way out.

choppermutt

Won't be going as far as house

Thanks for replies. I'll do my sums and go from there