ᐅ Earthworks for Preparing the Terrace and Driveway

Hello,

For those in a hurry, here is the short version; more details follow below: Regarding earthworks for preparing the terrace and driveway: Does the topsoil need to be completely removed here (and replaced with crushed stone), or can crushed stone be applied directly on (possibly compacted) topsoil?

Long version: Construction is about to start soon, and we want to prepare for our meeting with the earthworks contractor. The site looks almost level but slopes down like a bowl a few meters in, about 50cm (20 inches) below street level. The house will be built 25cm (10 inches) above street level; here, we will simply follow the structural engineer’s recommendations and the soil report, but that is not the main point here. According to the soil report, we have 40cm (16 inches) of topsoil, followed by sand and silt. Does the entire topsoil layer in the area of the driveway and terrace need to be removed? After removing the topsoil, we would be nearly 1m (39 inches) below street level and would then need to build up about 80-100cm (31-39 inches) of crushed stone up to the surface layer. Or can crushed stone be applied directly on the existing topsoil, resulting in around a 50cm (20 inches) crushed stone layer? If the soil may remain, does the ground need to be treated or compacted?

I look forward to your opinions and experiences.

Remove the topsoil. You won’t be able to compact it enough to completely avoid the risk of your driveway becoming uneven over time.

Topsoil removed down to the natural subsoil. Then refill half of the area with recycled material and cover the last 20cm (8 inches) with proper crushed stone! Make sure to compact everything thoroughly in between!