The difficult part is making everything "look good" with replacement tiles being dropped into an existing floor. It often looks NASTY. As in it looks WORSE than if it had been left alone.

The other thing that is DIFFICULT for some General Contractors is FINDING the REAL tile professionals who are CAPABLE of doing this sort of job. The GC will find it "difficult" because this level of tiling expert will NOT be part of his regular "guys" upon whom he normally calls. He will actually have to LOOK for a decent tile professional to get this done properly (ie. no complaints from the homeowner about how ugly the replacement tiles look). And then WRITING the cheque for said professional is also going to stick in his craw. That's going to be the most difficult of all.

Pulling up old tile can be stupid-easy or ridiculously hard. It will all depend on how WELL the original install was done. And how much effort it takes to pop off those old tiles. Any amateur with plenty of time and some arm strength can remove old tile. That's not the issue.

The issue the GC is looking at is maintaining the health of the hydronic tubes that are encapsulated in the concrete (I'm assuming the tubes are embedded in a concrete slab). Many builders/flooring professionals will use a jack hammer of some sort to remove old tile. This often damages the surface of the concrete. Without knowing HOW DEEP your hydronic tubing is, no one will know for sure how safe it is to use power tools to jack out those tiles.

Now it comes down to a tile professional digging out tiles AND thinset BY HAND for each and every tile that must be replaced. And then SANDING/GRINDING those areas without damaging ANYTHING ELSE!

Whew! That's a lot of work and a lot of expensive labour and we haven't even gotten to 'replacement' tiling yet. In fact, that's the EASY part.

As a novice you are welcome to pull any tile you feel is necessary. The problems come when you realize you need to dig out the thin-set BY HAND....on your hands and knees for hours and hours and hours without end. That's when paying the professionals what they are worth comes in handy.

If there are many tiles that need to be remedied, you might just want to rid yourself of the entire floor and start again - it might just work out to be the same price. I am not kidding about that.