water,nails, rust and hurricane sandy

Hello, i live in nj. My house was built in 1933 its a balloon frame 600 sq 1 bed room, 1 floor cottage. I had 4 1/2 feet of water during hurricane sandy. the house was gutted quickly. Its sound and inspected. Im replacing the subfloor and using hot dipped galavanized nails with a nail gun.

When i ripped up the old floor I took out all the old nails from the joists. A friend told me i can just cut them off. Do rusty nails damage wood over time. ?

My most important question is do nails continue to rust ?
I am wondering if i should renail the other parts of the house that i can reach that were exposed to water. No one in town seems to know the answer to this. I would hate to have my walls start to weaken over time. thanks tom .

Most metal fasteners are made of iron or steel which rust and expand when exposed to water. Fasteners, such as nails, should not be harmed by immersion in floodwaters, as long as they are allowed to dry soon after the waters subside. If nails are subjected to long-term salty moisture, rust may become severe and the nails may fail. A closer look at the fasteners should be done by pulling some out for inspection.

Rusted or weakened nails may not cause significant structural problems in the lower portion of a building, but why take chances. Renailing some of the lower portions of the framing most likely to be immersed by floodwaters would be easily done. In most cases, such as at the sill plate, the nails hold the wood in position but are not solely responsible for its support.

The exception to this is often porch floor joists. Porches are frequently fastened to the house only with nails which, if they fail, may cause the porch to collapse. I reccomend adding additional fasters and and hangers in these areas. If your porch was submerged, make sure it is well ventilated by removing solid porch skirts and allowing the air to flow freely. Once the moisture is removed, iron nails pose cosmetic problems by causing rust stains on finished surfaces. This problem can be corrected by driving the nails further into the wood, caulking them, and applying a primer paint with topcoat.

Hope this helps. Feel free to contact me if you need any addition advice.