I just bought them and a friend called them fiberglass, but I didn't choose them for that reason. Whatever the shell, the doors are interior hollow core 6 panel doors that are completely finished. My problem was the process for shortening them requires using wood glue when replacing the plug. If these are not fiberglass I don't know what that material is,
if it isn't wood and isn't porous, should I use another type of glue to make sure it is adhered well. I got them at Lowe's. I'm in SE Texas, near Galv Island. Thank you, hope you can help.