Let's read about shelter, shall we? We may take it for granted that we'll always be able to head for home, but what if home is too far away, flooded out, or worse, surrounded by the Living Dead? Ugghh. Such a hassle.
The link below is for the chapter on Shelter from the Army's Field Manual called Survival.
http://www.equipped.com/21-76/ch5.pdf
If you don't have an Army Navy Surplus store near your home, and you'd like to order a copy for your emergency library, I'm including a link for you to buy it.