How to repair a concrete void under a garage?

[kalvinder_bains]

Hiya, We have a concrete void that is running down two sides of my garage, as the soil has erodes over the years.  I'm after some advice on a DIY repair please?  Please let me know if I need to get professionals in to undertake this repair too, if its too complex for a DIY repair.  Much appreciated. concrete voidconcrete void whole length of garage on two sides

[kalvinder_bains]

Hi AlanM52, thank you for your forensic investigation. The evidence you provide is pretty compelling!  I would not be surprised if most of the built wasn't to spec, as I have lost trust in the building industry and certifiers. In my experience the certifier does the bare minimum to pass the various stages of the build.  They are not interested in quality and I can personally attest to this :).  We've been in the house for about 10 years and the garage was there before we came, so I'm not sure whether the garage sits on clay. 

Thank you for your thoughts

Kalvinder