1.   In both cases you may have to cut about half an inch off the bottom of the door to accommodate the extra thickness.

2.   The high-density composition increases the R-values of the batts without adding extra thickness.

3.   Trace the outline of the old door onto the new one, using your notes as a guide to add extra thickness where necessary.

4.   When you reinstall the toilet, the plumber will have to put an attachment on it to make up for this extra thickness.