does the irc require pressure treated bottom plates on a slab on grade house?

[Wayne Whitney]

OK, good enough, if that's the standard, I guess I shouldn't mess around trying to figure out if it really is necessary in my case.

Now I need to redo some nailing I already did with standard 8d common nails 4" o.c., between the 1/2" struct one plywood and the PT 2x6 sill plate. Would it be a problem to interleave corrosion resistant 8d common nails, yielding a 2" o.c. straight nailing pattern?

Thanks, Wayne

[Bob Morrison]

Robert:

Thanks for the chuckle! My structural notes do spell out hot-dipped galvanized.

[Bob Morrison]

That's pretty close nail spacing. My inclination would be to recommend that you put one galvanized nail every other space, or that you put the galvanized nail right next to (1/2") the plain nail.

Another option is to add blocking between the studs on top of the existing sill. Fasten the blocking to the PT sill with galvanized nails, then put in a row of plain nails through the sheathing into the untreated blocks. Kinda of a pain in the backside, but it depends on how much work you want to do.

[Wayne Whitney]

OK, thanks, I think I'll do both of these, put two new nails in between two existing nails, at the ends of the space, and then skip a space. So the spacing will be {1/2", 3", 1/2", 4", repeat}.

Cheers, Wayne

[Tom The Great]

I think, the foam padding, used to seal against slab,bottom plate air leakage counts as a moisture barrer too. However, I have to say you are reasonable to belive the use of 'treated' lumber, isn't cost prohibitative.

Sounds like good advice,

tom @