A photo would help a lot here.

Hi, thanks for the photo.
This is a bit of a grey area in my opinion. So did he goof on the height of the drain line?... yes. I'm not sure why that happened - if it was because the bottom of the cabinet is higher or what exactly happened. The trap will barely fit in that space and you can see it's not sitting squarely.

The next question: Is the requested fix reasonable?

That depends:

If the drain line can be re-configured in the cabinet so that the bottom of the trap isn't hitting the floor of the cabinet then yes the requested fix is reasonable. The cost would be a different waste kit or parts thereof(cheap) and perhaps an hour of time. That looks like it could be do-able. Here's a rough (very) drawing of what it could look like: Note the trap goes on the other side.

If the fix required removing the sink base cabinet (which would probably require removing the sink and possibly the counter top). That, in my opinion, is completely unreasonable.

Just a note about these kinds of issues - What he did isn't prohibited by code, it's not even particularly poor workmanship and there's nothing that says, "Homeowner must be able to clean under the trap and/or put shelf paper under it". I've seen plumbers do things that were "Unacceptable" and this isn't that. You may get further taking the approach that you both are going to give a little to get the results that you both want.

Thanks for the full response. I do not need a huge gap just enough so I can slide something underneath and through to keep clean. I have significant allergies so cleanliness is my health. There is no way to start from scatch and removed counter and cabinet. I have been in remodel hell for 5 months and not willing to relive that nor would the other contractor eat the costs for the remodel demo and replacement and I certainly do not have the money. I have fought my way thru this remodel with low quality and performance and overcome a lot only to end up with this final screw up by a "diamond" rated plumber who asks for high rates for their skills. Makes me ill.

I get it that you are frustrated. I don't know that this was entirely the plumber's fault (it might have been). If the floor was raised up (tile and tile backer, for example) and that wasn't planned for then this issue might not be all on him.

That said, I think that the drain line can be reconfigured in that space. I hope that he can take the suggestion without stonewalling.

The thing is once things become combative between contractor and homeowner, it's hard to get people to budge on either side.

What i know is that these kinds of projects are complex and expensive and the two sides may have very different ideas about how it's going to go together. Once it gets into very expensive finishes like counter top, contractors can be very defensive ( they don't want to eat a $10k countertop, for example).

My guess is that things like allergies weren't discussed in the beginning (or what that would mean for the job).

Point taken - common sense is not trainable. Floor was not raised. Plumber had access to all information including cabinet with kick space height and the wall was completely open for viewing and measure as plumbing was done before the cabinet was moved into place. I just did not think I had to stand over the person to tell them what to measure as they were the professional. Allergies aside common sense about ability to keep a space clean should be a factor in how to do an installation of anything in a space with potential for contamination and again I know that is my value system and others may not care about dirt and mold in their food areas. Sounds like I will probably have to pay another plumber to come in and make the changes - another cost. This will be 3 plumbers to do one job because the current plumber had to fix the mess the first plumber made when they put in wrong pipe and did not seal connections. Thanks for your input - enjoy life!

The proper fix is to pull out the cabinets, tear out the sheetrock on the wall, raise the plumbing to a more workable height, fix the wall, and reinstall the cabinet. Is that what you want him to do?

dchall_san_antonio, yeah, that's not going to happen. You forgot about the sink and the counter top as well. And if I was the plumber I'd say, "this has been properly plumbed - and if you want to pursue this legally, fine... but you will lose".

Reworking the drain in the cabinet is the realistic solution and is still a proper fix.

The proper fix is just like 3 other plumbers have done. Fire the client.