I just had my foundation walls poured yesterday for my new garage and everything will be backfilled next Friday at the earliest (I insisted they wait 7 days). They plan on backfilling with the original soil, which is heavily clay based and has been sitting in a huge pile in my front yard for 4 weeks. From what I've read, clay soil is the worst backfill to use because it retains moisture and exerts more force on the foundation wall. Should I pay extra to have them use a different soil, or perhaps add something to the existing soil? There will not be a basement or crawlspace on the inside, but rather a structural slab. Is this something a concrete contractor would do, or some other contractor? The builder wants to do it, but I don't have a lot of confidence that they will do it properly.

 

So no basement or crawl space just a slab?

Cant be deep, maybe a foot or two?

Don't think anything that shallow will make a difference what is used to backfill.

 

The deepest part is about 8 feet deep, which is a 10' x 8' area. This will be the mudroom with a structural slab above. The other area (25' x 13') is mostly undisturbed, but needs to be backfilled against the new wall (obviously). My main concern is the mudroom area. I'm sure if I don't say anything, the builder will use their mini-excavator and simply dump all the original soil back and maybe push down on it ever so often with the bucket. I highly doubt they will do it in layers and use a jumping jack.

 

Even after explicitly telling them to backfill in 12" lifts and mechanically tamp the soil, they simply dumped the soil back in the trenches and ran over it with the excavator (as close to the wall as they could get). I'm demanding that they dig the trench back up and do it properly. Is this the norm when having an addition built!?

 

This is a DIY forum, not a question and rant everything the contractor you hired forum!