If you're lucky, the two separate layers will stick together for a while, but there's always the possibility of the two separating and peeling apart, especially if water works its way in between.Light sanding prior to a second repair coat, as Ryan says, helps rough up the older cured coat and gives it some "tooth" for the new coat to grab onto, but the two coats will never fuse together as one, such as occurs with lacquer or shellac.

This will almost always eliminate financed offers masking as cash offers, and even if it doesn't, the 20% is plenty of remuneration for a buyer who lies and then can't get his financing.Btw, I pay all-cash for many of my properties and borrow the money for many of my properties.

DIY kits are very likley to peel do to insuffecient surface prep and week or no primer system.

We I walk other comps in the area, the refinished tile sticks out like a sore thumb and often is already peeling around the edges.  

AND WEAR A MASK OR RESPIRATOR!

While the 20-25% cap rate properties look appealing, it masks the problems associated with buying a property so cheaply (Unforeseen maintenance costs, tenant turn over, and etc).

I would suggest you to get good masks if you are going to do DIY renovation in this condition.

You don't have to peel the existing roof off first. 

The house next door has a ton of peeling paint.  

Nope, jumpsuits, dust masks, safety glasses, put the stuff in trash bags, into the back of an old pick up, off they went.