But if it comes out in pieces, it's still better to have a broken tile to show the tile guy than no tile at all.The part im trying to fix is in the shower under the window to the right you can see that they have covered it with silver tape and plastic.

One of mine is being rented by a plastic surgeon who is taking over a local practice.  

For quite a few years now those "screws" (bolts actually) have generally been made of a nylon or plastic material, with large thumb type wing nuts to secure them from the bottom while the head is held with a large straight blade screwdriver.

For example, if you needed surgery, would you start medical school?

If you own the house you could either install one or attach plastic to front opening for one rain storm and see if the problem persists. 

I understand leverage and utilized about $15k in plastic to remodel my current primary last year. 

[Case Study: Our bubble bath loving tenant who burned tea candles in the soap dish of a plastic tub surround and burned a hole through it.

I have a day job in the health care field, and do real estate in my spare time.Landlording is not easy, but it's not brain surgery.

If you put foam board in, make sure you peel of the sheet plastic, you'll get condensation that may run down dripping off in the wall cavity causing problems.The much better solution would be a metal roof over the old.

An effective way to check for moisture in the slab is to tape down a 2' square piece of plastic on the slab and leave it for a day or so.