I apologize if this has been discussed, as i am new to here.. but i am planning on using my basement for my shelter, the two placed i do not have protected well are the ceiling and the entrance to my fall out room. what do you recomend i use for the ceiling to protect against fallout and/or cbrne? is lead to heavy for a ceiling? what about my entrance door? should i pile cinder blocks and fill the holes with sand?