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plywood for basement subfloor


diy007's Avatar
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03-25-12, 04:10 PM   #1  
plywood for basement subfloor

I am finishing my 1600sqft basement. My basement is dry most of times/yrs. I added a new interior French drain system for 100yrs storm. I didn’t see any water when I dig down for the sump pump basin. The outside surface water was also addressed 2 yrs ago. So I assume the basement is safe for finished floor.

I am planning to put 1” XPS foam boards on top of the concrete floor, then cover them with plywood subfloor and then laminate/wood/ceramic tile (bathroom) floor.

I need your advice on the plywood subfloor first:
1. What’s the thickness I should use, 15/32”, 19/32” or 23/32”?
2. Should I use the sanded plywood or the regular plywood is just fine?
3. I should use the subfloor plywood but not sheathing plywood?
4. At homedepot there is a subfloor plywood called DryPly which has a water-repellent coating. I should use it or avoid it?
5. With the T&G, can I install the plywood as a floating subfloor without Tapcon to fix them with the concrete floor?
6. Where should I leave some gaps for plywood expansion or no need them at all?

thanks,

 
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03-25-12, 05:16 PM   #2  
First, I am not a fan of building up a concrete floor, but since it is done, here's my take:
1. 23/32"
2. Advantech or equivalent
3. Yes
4. SurdiFloor is fine
5. Don't see the advantage of fastening it with Tapcons if it fills the space up. After all you are just poking holes in a good underlayment to do that with.
6. 1/8" on non T&G sides is adequate.
I just finished a basement for a client and installed about 700 sf of snap lock laminate over the red underlaylment with white dots, and it looks and feels great (as great as laminate can feel - not a fan of laminate, either). We also tiled a bathroom in the same area, directly on the concrete. Others will have more to say, so stay tuned.

 
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03-31-12, 07:40 PM   #3  
Chandler has it pretty well covered, the only thing I can add is if you use sturdifloor for an underlay, you may want to use construction adhesive on the joints{tongue and groove} to keep them in place. Also not a fan of laminate, keep the dehumidifier on, just in case.

 
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03-31-12, 08:32 PM   #4  
Laminate is a temporary floorcovering. Putting plywood under it on concrete, makes it more temporary.

 
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04-07-12, 07:16 PM   #5  
10mil ploy + 1" pink foam + 23/32" AdvanTech subfloor + engineered wood floor

will be our basement floor.

The basement wall will be 2" pink foam + 2"x4" frame with fiberglass + 1/2" drywall.

should I build 2"x4" frame on top of the 1" pink foam or on top of the AdvanTech subfloor?

How about bathroom? should I put the tiles, toilet and shower on top of the concrete or on top of the

10mil ploy + 1" pink foam + 23/32" AdvanTech subfloor ?

 
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04-08-12, 04:11 AM   #6  
Wood to wood. Build wall on subfloor. All fixtures should be installed at finished floor height (tile), so extend any drain you have well above your subflooring. You can cut it off later.

 
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04-08-12, 04:24 AM   #7  
I have two floor drains and 3 cleanouts and one toilet rough are at concrete floor level. how can I handle them?

And I have interior french drain around the concrete wall. When i put wall frame plates, it will damage the french drain and also it may cannot hold the Tapcon well because some places the concrete may less than 1".

 
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04-08-12, 04:52 AM   #8  
Seems like this project is getting more complicated as you go. You will have to extend them to finished floor level. My concern is the floor drains. If you don't have primers for them, they will run dry and, if tied to your septic system, cause back up of sewer gasses. Your floor above will be level, so the drains won't serve a purpose above grade, since there is no slope.
Toilet may have to be dug out and extended with vertical capped pipe. You say "roughed" in, which tells me there is no flange, right?? Clean outs have to be raised above finished floor.
Glue your plates to the floor in thinner areas. No need for tapcons.
Why don't you post a few pictures so we can see the full spectrum of this project. There may be more boogers than are coming to light, now. http://www.doityourself.com/forum/el...your-post.html

 
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04-12-12, 09:27 PM   #9  
Plywood over basement concrete, is a real bad idea!!!

I see dew point & dry rot written all over that.

Poking 100's of holes in a moisture barrier is a real bright idea! Think about that, for just a minute.

I'd cap it with self leveling cement, install the carpet and install the tiles, and install a floating engineered wood and cushion, over a double moisture barrier.

 
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05-04-12, 09:24 AM   #10  
Finally I cleanup the site and got few photos here. I am thinking about put subfloor only in the half without cleanout, toilet, and floordrain, and leave another side "as is". any better ideas?

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05-04-12, 08:17 PM   #11  
Can I use this type of flange to avoid redo riser?

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