ᐅ Filling height: soil, topsoil, compaction, etc.

Hello everyone,

Our foundation slab is in place, and all the excavated soil is currently piled at the back of the property. We want to level the garden and the entire plot to the terrace height and now need to clarify how much soil will be required. Any excess soil would be taken by our neighbors. We roughly estimate about 60 cubic meters (cbm) of excavation material and around 15 cubic meters (cbm) of topsoil available.

Questions:

• Is it common to add about 20cm (8 inches) of topsoil? And 30cm (12 inches) where shrubs will be planted?
• The excavation material would be piled up to the height of the raw foundation slab level, right? Then add 20cm (8 inches) of topsoil, resulting in a level surface to the finished floor height (the floor construction above the slab would be 16cm (6 inches)).
• How much volume loss due to compaction can be expected for the fill soil? Around 15% as a rough estimate?

It would be great if someone with experience could help me with these questions. That way, I can better plan the use of the available soil.

Is there anything important I might have forgotten?

Thank you very much.

allstar83 schrieb:

• You add about 20cm (8 inches) of topsoil? 30cm (12 inches) where shrubs will be planted?

Personally, I think that's too little. We added about 30cm (12 inches) of topsoil and are currently planting a hedge. So the 30cm (12 inches) is basically gone, and the worst debris is visible underneath. I really hope the plants will take root; otherwise, we face a huge challenge.

allstar83 schrieb:

• The excavated soil would be piled up to the rough floor slab level, right? Then add 20cm (8 inches) of topsoil on top, and you'd have a level surface up to the finished floor (which has a 16cm (6 inch) build-up on the slab)

That’s definitely enough for lawn. For other purposes, it might be a bit tight. And don’t fill everything at once, because you might have to remove soil later for a terrace or something similar.

allstar83 schrieb:

• Approximately what percentage of the piled-up soil is lost due to compaction? Around 15% as a rough estimate?

It’s between 20% and 25%.

With a bungalow, you also step up one level from the top edge of the property into the house. Otherwise, after heavy rain, you’ll have a puddle in the living room.

Nida35a schrieb:

With bungalows, you also usually step up one level from the top edge of the plot to enter the house. Otherwise, after heavy rain, you’ll have a puddle in the living room.

Isn’t that what those drainage channels in front of the patio doors are for?

Heavy rain exceeds what the gutter can drain, and the terrace should have a slope; having everything at the same level will not work well for long.

What I want to say is,
don’t dispose of any topsoil until the site preparation is fully completed.
Excavations for the terrace, paths, cistern, and the final ground level need to be correct in the end.
We ended up needing an additional 20 cubic meters of topsoil.