"Real world" sub base depth for tarmac footpath
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Joined: Thu Sep 23, 2021 9:34 am

"Real world" sub base depth for tarmac footpath

by joeka101 » Thu Sep 23, 2021 9:45 am

Hi guys and gals,

I'm replacing a foot path around my house (25m2) which is currently stone slabs (irregular) laid direct on soil. Appears to have been there for minimum 30 (likely 60+) years on well drained, very compacted (no 'give' to feet or spade) medium heavy clay based soil. No significant signs of subsidence, break up of grouting mortar etc.

Bounded by house wall and a garden wall. Will only be for foot traffic. Intend for 40mm binder and 25mm wearing layer tarmac (to be done by a contractor) with soldier course of concrete haunched paving blocks at edges.

I've read a lot of guidance (including excellent pavingexpert.com) which suggests anything from 75-150mm of compacted sub base for this purpose. I appreciate the logic for minimum depth (twice the size of largest rock particle) but this all seems like overkill on such a compacted sub grade for foot traffic only! I am considering 50mm well compacted (wacker plate) type 1 MOT.

I don't want to 'bodge' anything, but in the 'real world', what would people suggest is adequate?

I'd much rather lay on top of current sub grade (there is enough gap to DPC) than excavate by hand!

Cheers for any advice.


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