Excavation for concrete slab

[Faz786]

Hi all,

started scraping/excavating, but for: 3m x 4.5m concrete slab with Type 1 MOT, A142 mesh, DPM and 100mm concrete slab is this enough excavation?

 

[Wayners]

200mm down from finishing level.
100mm of type 1 and 100mm of concrete.

Is that what you are thinking?

 

[Tigercubrider]

Don’t you need sand as a blinder before the dpm?

 

[Faz786]

Not sure

 

[Tigercubrider]

I always thought (am a DIY) that the MOT needs compacting, then about 50mm of compacted sand. The DPM sits on the sand or the MOT will puncture it.
Could be wrong!

 

[stevie888]

You want to remove all the topsoil. Top of slab wants to be above ground if you're putting a shed on it. Type 1 should be compacted but you only need a thin sprinkle of sand to protect the DPM. You may need more type 1. Crushed concrete is a good alternative and you can often get it as type 1 graded. Type 1 compacts better a bit damp.