Soil movement as a sub-base Post your questions and get answers regarding all areas of drives, pathways and patios

[Sue Self Build]

I am raising the level of extension with existing house floors with paving area raised to same level. I will need to fill up a depth of 40cms for raised paving encased in a single brick wall surround.
I have lots of extra soil that I could use but worried about settlement. Type 1 should be no more that 20cms I've read compacted every 5cms. Should I order type 2 filling or use broken bricks and slab bits. I have some but don't know how that works having gaps in between them and will they move?
It also worries me that I had to move the manhole from within the new extension site to outside the perimeter. I dug the channel redirected it and filled the channel back up with soil. Would that sink as well?

Thank you very much for any advice. Sue.

[stoneyboy]

Hi sue self build.
Use you hardcore first and break it up into smaller pieces and capacity it as you go. Once this is nearly up to the level you require top off with something like pea shingle to fill the gaps. This should give you a stable solid base.
Your extended drain run should have been enclosed in pea shingle, it’s probably worth removing your soil fill and replacing it.
Regards S

[Sue Self Build]

Thank you, Stoneyboy,
Yes, that makes perfect sense - the pea single will then fill the gaps in the bigger stones and then I can use the wacker plate to compact down before using the type 1 on top.
As for the new drain extension I encased the pipe in pea single all the way around I think about 10cms then filled back up with soil. That was some months ago so hopefully the soil has compacted back down by now. This is where the extension floor will be so ready to start laying type 1, sharp sand, DPM, insulation, DPM, concrete and screed. I intended to hire the wacker plate and do that and the patio base at the same time. Thank you, very much for your advice. Sue.

[stoneyboy]

Hi sue self build,
Thanks for the feedback, hire a small wacker which will be easier to manoeuvre and will compress the base better.
Regards S

[Sue Self Build]

Thank you, Stoneyboy - will do.