Replies

1. 
   SamT | Feb 13, 2005 07:12pm | #1

   CB,

   Expanding wood will split rock, I don't think 300 nails will stop it.

   BTW, the maunfacturer has no clue what onsite conditions are, the floor may still be in a shrinking mode when you lay his product, pulling it all together.

   As to the filler, that may have something to do with acclimatization. Certainly is counter intuitive though.

   SamT

1. 
   zendo | Feb 13, 2005 10:05pm | #3

   I think you also have to think of the wood as expanding on the fiber or cellular level, not as one unit.  adding 300 nails will just make it expand further to compensate the width of the shanks.

   Ive never seen anyone fill the gap on a subfloor unless they were putting down ceramic tile.

   -zen

2. 
   cleanwater | Feb 13, 2005 08:13pm | #2

   I have seen a crew sanding down the seems of all the decks in a new house in an effort remove the hump made by expansion/moisture and it looks like a real pain.  I wouldn't even wanna think of dealing with the roof deck.  I think it is alot easeir to read the specs and follow the reccomended procedure for spacing as well as orientation.  It may be of intrest that some of the stuff on the market these days has different expansion properties.  Check out last issue of fhb #169 page 94. 

    

3. 
   DanH | Feb 13, 2005 11:35pm | #4

   Keep in mind that they also want you to allow for the fact that the sheets are 1/16" undersized. Those sixteenths add up when you make hundreds of thousands of sheets.

1. 
   cb900 | Feb 14, 2005 12:17am | #5

   I'm not sure how those hundred thousand sheets are going to add up on my floor, Dan. I understand that the wood has to expand, and I plan to follow the man. directions. I am installing ceramic tile so the gaps are suppose to be filled. I guess I just don't understand how filling the gaps won't have a negative affect on allowing the expansion of the panels. This is a small room I'm working on so I'm not at all worried about this particular floor. But if I was doing a ballroom what would be the consequences? Actually, bad example. Who wants to dance on ceramic tile!

1. 
   zendo | Feb 14, 2005 01:37am | #6

   For your tile, backer board would be a better solution.

   -zen

2. 
   Lawrence | Feb 14, 2005 04:45am | #7

   Plywood expands and contracts with the weather. Filling the joints with solid material will cause the sheets to buckle. Don't fill the gaps-just trowel over with your thin set. That cement has a bit of give to it... and it will crush for the little bit you get in the joint. They are worried about buckling between joists enough to crack the tile or make them come loose.

   The high end guys normally go over the sub floor with 3/4" of dry set for reno work... portland and sand with very little moisture... they use a 3/4" piece of copper near each end of the room and screed it level with those. Of course this is atop a layer of mesh.

   Hope this helps...

   L

   ( I didn't always just do pretty stuff)GardenStructure.com~Build for the Art of it!

4. 
   jrnbj | Feb 14, 2005 07:31am | #8

   IMHO, the expansion joint spacing is for the one inevitable soaking that every new house deck gets before the roof is on....if you are 100% sure the plywood will never ger wet, butt it up just kissing together, otherwise follow the 12 penny sinker spacing....