Tore up an old floor in bathroom to have new plumbing installed but realized there is a slight grade heading downhill towards my toilet ,that will soon be installed along with my sink... what can I do besides tearing up my floor to level it out near the toilet and sink?will there be toilet issues if I leave this floor a little crooked?. my level says I need to raise the floor about 1/2 inch... any products out there that can help and how do I use them.. thanks