I am in the process of installing cement fiber siding (not Hardee brand
tho) also. I am using nails specifically made for that purpose-- don't
know if that is what you are referrring to, but I am predrilling my
siding also. As for the foam you are talking about and keeping rats out,
don't count on it. They can and will gnaw through it with no trouble at
all. It is like candy to them. Use galvanized flashing where you have
any areas that rats and other rodents can enter. Larry