ADDING A SECOND ROOF CAN SOLVE YOUR PROBLEMS
If you’ve got a roof that’s leaking or is in bad shape, or is out of warranty, then adding a second roof over top of it can solve most of your problems. As long as the original roof is structurally sound, this is a good way to get a new system that is under warranty, will have fewer leaks, and will last longer than the old roof.
Adding a second roof requires you to go in over top of the existing roof and install a new system directly over top of the old system. You don’t have to tear off the old roof, you simply install the new roof right over top of it. You will probably have to make some structural changes to make sure the new roof is properly installed and adhered, but you won’t have a huge gaping hole in your roof for any period of time. However, there is one major drawback to the approach of adding a second roof. Let’s check out that drawback right now.

Limited Availability
If you choose to add a second roof on your building, this can only be done once, and then any subsequent roofing will require BOTH original roofs to be removed. Complete tear-off is required of both roofs which can be expensive, but adding a second roof works well for that one time it’s an option. Once you’ve installed two roofs on your building, you are no longer permitted by law to install another roof over top of the existing system. You cannot have three roofs on your building. But, you also can’t just tear off one; you have to go back and tear off both roofs – exposing the inside of your building to the elements – before you can install a new roof. So, this is really just a temporary avoidance of exposing the inside of your building to the elements rather than a solution to the problem.
Conclusion
Adding a second roof is a great way to replace your roof without tearing it off, but is only a great option once. After that one time, you’ll have to remove both roofs and then install a new roof. Instead of adding a second roof to your building, consider a renewable surface, such as spray foam or a restoration coating. These can be re-applied many times without the need for tear off.