Why do nails start to work their way up on an outside deck after a while?

[raccoon]

Or is it the wood shrinking away from the nail? :shrug:

[closeupready]

1. That is the wood seeking equilibrium.

Also, just as temperature changes expand and contract concrete, same goes with wood (and every other material).

[Cronus Protagonist]

2. Pressure from walking on them and the warp of weather damage

n/t

[PetrusMonsFormicarum]

3. Expansion and contraction

is my guess. My neighbors have a deck made of the wood composite planks and this doesn't seem to be an issue, 4 years after they had it built.

[Viva_La_Revolution]

4. The shrinking and expanding of the wood does that...

just get yer hammer and go bang em back down every few months. :)

[GodlessBiker]

5. That's what nails are paid to do.

[jberryhill]

15. ...and if they are two-penny nails, they do it cheaper /nt

[Richard Steele]

6. The natural expansion/contraction cycle of the wood slowly forces them out.

Occasionally, boards will actually WARP upwards, lifting the nail,
and then relax back down again, leaving it standing proud.

[coriolis]

7. The wood does shrink some when it cools and so does the nail but not as much!

Each time the temperature rises, the wood which has a lower coefficient of thermal expansion gives the nail a tiny "push" which is toward the 'outside', or the path of least resistance. Over years, a nail can actually get pushed all the way out! We fight the problem with our deck...hammering the nails back in is a very temporary solution because the hole is already there and so the wood hasn't much ability to grab the nail. :-)

[Win]

8. They're proud.

[xchrom]

9. because it really is personal for nails -- they ARE out to get you. nt

[OnceUponTimeOnTheNet]

10. Is it possible to replace them with screws?

My FIL tried this solution, he got several more years use out of that deck.

[raccoon]

12. Good idea. nt

[TheMadMonk]

13. Use zinc galvanised screws. Esp if the wood is treated.

Cadmium plated screws will rust out in no time flat in treated timbers.

Screws are definitely the go if installing a new deck.

In an existing deck, pull each nail as it stands proud and replace with a screw.

[Tesha]

16. Some decking now uses concealed clips rather than face-screwing/face-nailing. (NT)

[eppur_se_muova]

11. Probably just a case of slow "slip-stick" motion. nt

[struggle4progress]

14. Cuz some idiot built it using straight new nail instead of old bent ones

Straight new nails go in easy and come right back out easy, too

It takes more skill to hammer in an old bent nail, but it will stay in place