I would want to fix the leak before repairing the cabinet.

There is no leak. The stain is due to water splashes according to the contractor. There is no water on the inside of the cabinet. The stain is only on the outside.

There is zero way that your contractor is in your bathroom being careless splashing water about. Get the kids to take better care of nice things and your problem is solved. If they don’t, then you’ll get to replace that in short order.

I think you misunderstood me. The contractor did not splash any water. He said the stain was due to us splashing water, however this sink is used by my husband and there is little splashing. There are no kids in the house. I think the trim was not properly caulked, so a minor amount of splash caused the stain

Do you have a photo? I am confused as to where the stain is located, and what it is that should have been caulked. Or how it could be covered up with granite?

I thought I attached a photo. I will try again

Too close to the sink. The ends of the box are going to wick up water. No amount of caulk or splash will stop that.

That is poor design. Who designed that? There’s insufficient clearance to the sink. It really needs to get removed. It’s far too overbearing and bulky as well.

To the counter hutches should be much more shallow, and give you at least 12” to the sink. And preferably rest on a stone riser even then. In general, they are a bad idea in a small bathroom.

If storage is needed that badly, a single sink with a linen tower should have been done.

with the sink that close to the cabinet I think it's impossible to factually state that there's been no splash/the counter hasn't gotten wet/etc. ever. As others have said it needs to be reworked to expect that it will get wet during normal usage.

Other than reworking the design, is there anything I can do to mitigate further damage that will not be too expensive?

I'm not a decorator, far from it, but if that were my bathroom that cabinet would be gone yesterday. It adds too much mass and breaks up the space.

Besides, as others have said, you can't put wood in a place like that and expect it to stay dry and attractive.

Seriously, I'd rip it out. It just unbalances the room. If you need the storage, put it on another wall or something. Maybe you can tuck it in a corner where the damaged bottom edge doesn't show.

"Other than reworking the design, is there anything I can do to mitigate further damage that will not be too expensive?"

No, either remove it or do not use either sink. Poor design as mentioned above.

I don't think it's the contractor's responsibility to fix that...but he should have warned you that an installation like this was not prudent, specifically because this problem is predictable.

Thanks for all the feedback. Will a granite strip be a good idea to cover the damage and prevent further staining? I can't afford an expensive remodel.

May work as a bandaid but the only way to stop the issue entirely is removal.

> the only way to stop the issue entirely is removal.

'Fraid so. That cabinet is just in the wrong place. There's no way to keep it dry.