I am building a deck!! I am just starting to lay the decking-only 8 12' boards done. On the web sites I have been reading instructions from they say to use a 16d nail to make the gaps between the boards. Two neighbors stopped by and were horrified. They say that the treated lumber is wet and there should not be a gap, I should lay the boards side by side and as the wood dries the gaps will get there on their own. Are they right?