Replies

1. 
   FastEddie | Dec 08, 2007 02:36am | #1

   Absolute min is 5/8" but used 3/4" if you have the clearance.  Advantech is a good brand, it's actually an osb product.  Plytanium is similar.

   "Put your creed in your deed."   Emerson

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

1. 
   rick12 | Dec 08, 2007 02:43am | #2

   Does Advantech come in different thicknesses?  Is the advantage of Advantech in that it is more water resistant? Is Advantech better than say a good AC doug fir ply?

1. 
   FastEddie | Dec 08, 2007 04:07am | #3

   Advantech and Plytsanium are moisture resistant and tongue & grooved.  If you go with a plywood, be sure it is rated for use as floor sheathing.  You don't need to spend the money on A-face plywood, you won't see the pretty face after it is installed."Put your creed in your deed."   Emerson

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

1. 
   96summit | Dec 08, 2007 04:27am | #7

   If you can find it, Multiply Flooring Underlayment is a solid product to be used over the subfloor to give a very rigid foundation for any finishing application - ie. 5/8" T&G subfloor with 1/4" Multiply over. Comes in 1/4" and 3/8". Make sure you run the grain of the panel perpendicular to floor joists. Your results will be solid.

2. 
   rick12 | Dec 08, 2007 04:27pm | #12

   "If you go with a plywood, be sure it is rated for use as floor sheathing."

   I wonder what exactly makes it a floor sheathing? Exterior glue, species of wood, number of ply?

   The ply I'm pulling up totally delaminated from bathroom leakage.

1. 
   FastEddie | Dec 08, 2007 04:49pm | #13

   what exactly makes it a floor sheathing?

   I'll give you the smart a$$ answer: the grade stamp that says it's floor rated.  Actually I don't know the specifics."Put your creed in your deed."   Emerson

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

2. 
   BillBrennen | Dec 09, 2007 07:59pm | #19

   Rick,The key difference between plywood rated as combination sheathing/underlayment ( AKA "Sturdifloor") and plywood rated only as sheathing with the same thickness and span rating is this: The layer of veneer under the top face has had its voids plugged so that point loads don't crush through the surface. Also, the Combination product is always T&G.The void issue is not a factor with OSB, only plywood.Bill

2. 
   RedfordHenry | Dec 08, 2007 05:54am | #11

   I'd say that Advantech is superior in several ways.  Besides its moisture resistance, it's usually dead flat (unless it's been stored incorrectly) so no wrestling tongues into the grooves.  Just a couple of taps with a framing hammer and its usually seated.  Comes stamped with layout lines for nailing onto joists, plus it's less expensive (about $23/sheet for 3/4" vs. ~$30/sheet for T&G plywood).

2. 
   renosteinke | Dec 08, 2007 04:19am | #4

   I use only 1 1/8" subfloor grade plywood, as long as the site conditions allow it.

   This material has a tongue-and-groove to the long edge. There is never any bounce or squeak to the floor. You need never worry about the floor being too flexible for any kind of tile.

   The best part is that this material costs the same as 3/4" plywood.

1. 
   jonblakemore | Dec 08, 2007 04:26am | #6

   "The best part is that this material costs the same as 3/4" plywood."Where do you get it from? 

   Jon Blakemore RappahannockINC.com Fredericksburg, VA

1. 
   renosteinke | Dec 08, 2007 04:52am | #8

   Our Home Depot has it in both plywood and OSB versions.

1. 
   redeyedfly | Dec 08, 2007 04:57am | #9

   It seems everyone skipped over the line about the oak floor going over the top. If you're talking about 3/4" t&g oak installed perpendicular to the joists you don't need to add anything. You could just install that directly over the joists and have a solid floor. No diaphragm, but a solid floor to walk on.

1. 
   FastEddie | Dec 08, 2007 05:30am | #10

   I did some repair work in a 1926 house that had oak strip flooring directly over the floor joists over a dirt crawlspace.  I can't imagine new construction or major remodeling being done without a subfloor.  It also had lead toilet drains & k&t wiring, some parts still hot.

   "Put your creed in your deed."   Emerson

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

   Edited 12/7/2007 9:31 pm ET by FastEddie

2. 
   Piffin | Dec 09, 2007 04:31am | #15

   You need to have something to nail it too 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

3. 
   redeyedfly | Dec 09, 2007 04:38am | #16

   joists.I'm just saying if he has a floor height problem and he's using solid 3/4" oak flooring perpendicular to the joists, replacing the 1/2" with 1/2" will be fine.

   Edited 12/8/2007 8:39 pm ET by redeyedfly

4. 
   Piffin | Dec 09, 2007 05:01am | #17

   I was gettiung at the fact that 1/2" does not hold nails well 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

2. 
   jonblakemore | Dec 09, 2007 01:31am | #14

   I'll have to look again. I'm pretty sure we don't have 1-1/8". I would buy it in a heartbeat if the $/SF was the same. 

   Jon Blakemore RappahannockINC.com Fredericksburg, VA

3. 
   JDRHI | Dec 08, 2007 04:22am | #5

   Kick it up to 3/4".

   You won't be sorry.

   J. D. Reynolds
   Home Improvements

    

    

   
   

4. 
   Parch | Dec 09, 2007 07:23pm | #18

   Not sure where you are building, but according to the Residential Code of NYS Table R503.1 Minimum Thickness of Lumber Floor Sheathing for 16" Joist Spacing requires a net min thickness of 5/8". I always use 3/4" T&G. If it is existing and doesn't need replacement (doesn't show any signs of failing) and you are re-installing 3/4" thick Oak T&G Wood Flooring over it...it's not great but it will do. If you can, I would replace it since it would be a better job and that means no call backs.

5. 
   jpshadowrider | Jan 18, 2015 05:24pm | #20

   subfloor thickness

   I'm pulling up damaged plywood.  I'm getting 1/2 plywood for free.  Can I put 2 layers of 1/2 OSB over the joists and if I did, should I glue them together.  I'm not worried about the height.  

6. 
   renosteinke | Jan 20, 2015 01:51pm | #21

   Just Do It Right

   I that so much to ask?

   All plywood is not NOT the same. That's the first thing to recognize.

   A bit harder is to recognize that in every field there are professinals, who know from experience just what they need. In a fancy form, this shows as the various codes and standards that pros follow.

   There are specific standards for subfloor material.While other materials might 'work,' might even be 'better,' your best way to be sure you're using the right stuff is to buy the product specifically made for the use.

   Probably the biggest requirement is that it all flex together.This means  tongue & groove connections between plates - or solid support under the joints. It also means that the 'grain' of the pieces all goes in the same direction. Fail to do this, and you just might cause the finish floor to fail.

   Rated sub-floor material is NOT expensive,or hard to find. It's worth finding a real lumberyard; my local box store 'pro' had never heard of sub-floor ratings in "all his 14 years." 

   Standard sub-flooring is availablein 3/4"and 1-1/8" thicknesses. The latter matches the older '5/4' lumber used forsubfloors.

   You mentioned you were repairing a bathroom leak. This suggests two other things you need to address with the floor framing. First, there is probably damage to some of the joists;you'll need to 'sister' blocks to the damaged joists so that the tops are all even.

   Second, it's very possible the floor is not properly framed. Very often when the plumber comes in to run his drains, he finds a joist in the way -and out comes the big saw. HE cares not at all about the weak spot he has now made in the floor- setting the stage for failed tile, leaks, rot, and eventual replacement.  Now is the time to fix the framing.

   REMOVE old nails if you can. Lay down the right adhesive. Nail the new stuff according to the nailing schedule.

    And .... it probably wouldn't hurt to seal the wood and  punch tiny 'weep' holes in any areas where water is likely to show up in the future.    These are the areas around the toilet and along the edge of the bathtub / shower. I'd also extend the 'finish' floor under these areas .... why give water a way in?