I agree with Dunbar that your builder $%&#ed up and should fix it. I’m not sure how your builder works, but in my area it is usually a plumbing subcontractor who lays out the pipe runs. When I lay out the under-slab DVW pipe, I make sure the runs are as they should be according to the plans and that the risers and stub-outs are vertical. I assume your problem is really due to non-vertical risers and not due to some unlevel concrete placement.
For what it’s worth, I have had to fix the kind of problem you describe, i.e. a non-vertical riser and skewed toilet flange (not originally placed by me…I don’t make that kind of mistake). The way to fix that mistake is to cut the riser below the slab (an internal pipe cutter works well) and then to insert a new flange that rests properly on the slab. It’s a relatively simple job for someone equiped with the right tools, but it might be an expensive and pain-in-the-ass task for a DIYer.
NtP
