Replies

1. GBA Editor
   Martin Holladay | Jan 27, 2015 07:44am | #1

   S.R. Kod,
   So, on another web forum, someone told you that your subfloor assembly needs to be re-done. Did this person tell you why?

   We don't really have enough information to answer your question. Is it possible that your OSB subfloor will rot? Of course, especially if it is installed in a basement with water entry problems.

   But we don't know if your basement has water entry problems. Maybe your basement is bone dry. So, first of all, we need more information about your basement.

   If your basement is damp, you might want to read this article: Fixing a Wet Basement.

   Assuming your basement has no water entry problems, your floor assembly will work. It probably would have been better to make the rigid foam layer a little thicker, but 1 inch of rigid foam is better than nothing.

2. 
   Dana1 | Jan 27, 2015 07:49am | #2

   That stackup works fine as long as the basement isn't prone to flooding.

   It's a good idea to use tongue & groove OSB and TapCon it to the concrete 24" o.c., or a least fasten the corners down with a couple in the middle of each sheet to avoid it from developing "potato chip" curl or waves from normal seasonal moisture cycling.

   In some ways it can be better to put the poly between the foam and OSB rather than the foam & concrete, since any irregularities to the concrete surface would create voids where water could pool on top of the poly and take forever to dry through the foam, but unless you flood or spill tubs of water down there it's of little concern.

   Ideally the poly would extend up the foundation wall 6-12", but if there is no history of liquid water seepage at the walls that's not a big deal either.

   What was the theory behind the rot potential being offered by detractors on that other forum?

   I'm curious what the

3. 
   sxk | Jan 27, 2015 09:05am | #3

   Thanks for the answers. My basement is visibly dry. A small poly sheet taped didn't collect any moisture after few days.poly does extend a few inches on the walls. I nailed down each board with 5 tap cons, 4 in the corners and 1 in the center.

   On the other forum only reasoning they have was that they have ripped a lot of floors that rotted with the way I did and that it will trap moisture.

   May be that being a newbie I am not asking the right way. You need some knowledge to ask the right questions in the first place.

   Thanks

4. 
   Dana1 | Jan 27, 2015 10:50am | #4

   I'm sure moisture-prone basements would have problems with any stackup that included OSB. As long as the finish flooring is at least semi vapor permeable (hardwood or ceramic tile, but not asphalt tile or vinyl) there is no moisture trap here.

5. 
   sxk | Jan 27, 2015 12:13pm | #5

   Ok. Will laminate be ok? Just easier fora diy guy to do. Other wise I can get hard wood
   .
   Thanks

6. 
   iLikeDirt | Jan 27, 2015 03:49pm | #6

   If you're leaning toward laminate, do engineered hardwood instead. A lot of that stuff goes together just like laminate, but of course the top is real wood not a varnished picture of wood.

7. 
   sxk | Jan 27, 2015 04:45pm | #7

   Will do. However on a related note will a carpet be better on this occasion _ more permeable to vapor? Just me thinking. Wife wants laminate or hardwood look. I don't mind any. And the choice of hardwood over laminate- is it for a moisture related reason or because hardwood is a better product in general?

   Thanks

8. 
   sxk | Apr 19, 2015 08:22pm | #8

   Hi there

   Finally getting to floor coverings. I am looking at bamboo or tiling. I like the idea of tiles.

   Can the ceramic tiles be laid on top of the OSB or should I lay the plywood or cement board and lay the tiles on top of that? I mean can I put the thinset on top of the OSB and then embed the tiles in it? I am not sure if OSB will start warping from the moisture in thin set.

   How does bamboo hold up in this stackup I have? Will bamboo trap any moisture in the OSB?

   Thanks

9. GBA Editor
   Martin Holladay | Apr 20, 2015 05:58am | #9

   SR Kod,
   No, you cannot install ceramic tile directly on an OSB subfloor. You need a substantial, sturdy, smooth subfloor / underlayment system under ceramic tile.

   Since this is new to you, I suggest that you Google "ceramic tile + subfloor" and read a few articles. Or consider hiring a flooring contractor.

10. 
    sxk | Apr 20, 2015 08:47am | #10

    OK. Thanks. In that case an underlayment and bamboo over that sound OK? I did read up on the bamboo for basement but can't find any where where they say it is OK below grade. I guess so many other factors come in to play it is hard to give a simple guidance that is full proof for newbies like me. I will steer clear of tiles.

    Thanks

11. 
    user-2890856 | Apr 20, 2015 09:03am | #11

    I would add that the OSB is not secured substantially enough for a tile install . Fastener pattern should be looked at since there may be a very high chance that this will move during normal use . As the subfloor members move you will experience grout lines failing and possible cracking of the tiles . Secure that OSB layer as if it were structural because it will be in your application . Also employ a tile membrane to further lessen the chance of this .

12. 
    sxk | Apr 20, 2015 12:56pm | #12

    I actually went back over the osb and now each board is secured with 12 tapcons - after reading the advise here.

    I am thinking of bamboo. As Mr Holladay,s post, I think tiless are above my skill level.

    Thanks

13. 
    Dana1 | Apr 20, 2015 01:18pm | #13

    Since the subflooris fully supported by foam & slab, assuming the slab was pretty smooth to start with the 1/2" OSB will flex less than 3/4" OSB between 16" o.c. joists would. Tile isn't out of the question- it's a matter of judgment. If it feels like it has any appreciable "give" to it, it's probably not a candidate, but if it feels firm everywhere it'll probably be fine.

14. GBA Editor
    Martin Holladay | Apr 20, 2015 01:53pm | #14

    Just to clarify: I never said that tile was out of the question -- just that tile can't be installed directly over OSB. Tile requires a different underlayment -- for example, plywood underlayment or cement backerboard. Either of these underlayments can be installed on the OSB.

15. 
    sxk | Apr 20, 2015 01:57pm | #15

    Sorry. I did not mean to blame you:-)

    After reading more about it I thought it will be safe for a novice to go with some thing like bamboo. Thanks

16. Expert Member
    MALCOLM TAYLOR | Apr 20, 2015 03:49pm | #16

    John Bridges Tile Forum has useful calculators for joist spans, spacing and depths of underlayment for tile substrates. A good resource for all things tile.