What is the best way to do this? Our lawn is mainly crabgrass and foxtails. We would like to replace it with sod. Should we spray roundup to kill the whole thing and then dig it up? What about using a sod cutter - the ground is pretty hard and actual grass is sparse so I am not sure that would work? Or should we dig up the lawn (weeds) first and then spray roundup?

I know once we dig out the weeds, etc. we need to do a soils test and all that but I just want to know the best way to get rid of the old ugly stuff so we don't end up with a weed patch and/or doing more work than necessary!

Thanks.