treated vs non-treated plywood

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  #1  
Old 03-26-09, 09:45 PM
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treated vs non-treated plywood

Hello,

I've read many of the forums, and found great answers to most of my questions. Thanks to all the previous posters!
What I did not see, and may seem obvious, is should I use treated or non treated plywood for a bathroom subfloor install?

Here's the current specifics:
small room, 5 x 6 ft.
100 year old house, oak 2x8 joists on 16 in center
tongue-n-groove 1x4 floor
may be plywood or osb layer
then vinyl

my plan is to remove the vinyl, add 5/8 plywood, then SunTouch Warmwire for electric floor heat , unmodified thinset, ditra, unmodified thinset, and porcelain tile.

Thanks
 
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Old 03-26-09, 09:55 PM
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correction, I think the 2x8 joists are oak, but do not really know for sure. This house is older than me grandpappy, kinda hard to tell.
 
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Old 03-27-09, 03:30 PM
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Hi!

You will want at least the 5/8" exterior grade AC or BC plywood. You do not want "pressure treated."

What are the unsupported span of those joists? That basically means how long are the joists before they are supported by a post/foundation/wall, etc? If this span is less then 12', you should be good to install ceramic/porcelain.

Your plan seems sound, just don't use Home Depots unmodified. Head to Lowes or a flooring store for better stuff.
 
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Old 03-27-09, 07:14 PM
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I do NOT agree with your plans.

1. Chances are the vinyl is glued to 1/4" thick something or another. If so, this 1/4" wood should be removed along with the vinyl in one operation.

2. If you use unmodified thinset to stick Ditra to the subfloor you will be re-doing the entire job within weeks.

Also, people should stop calling warming mats floor or radiant "heat". It will not heat the room, it will only warm the floor.

Edit: On the joists, If they are oak the span should be under 10' max, if in perfect condition and installed perfectly....good luck with that.

Jaz
 
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Old 03-27-09, 08:53 PM
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Thanks both for the answers,

HotinOKC,

Thanks for clarifying on the plywood, I'd head to Lowes and get the right plywood, and thinset also.

As for the Ditra, I'll be doing it exactly per the instructions on the package. It calls for FlexBond or Versabond underneath the ditra, and PremiumPlus/MasterBlend/CustomBlend on top.

The span is less than 12 ft. I'll put a tape to it tomorrow.

Jaz,

Whats under the vinyl, if it needs to come up, I'll remove it also,just do not know what it is yet.

I am aware the warmwire is not primary heat source. In case there's nomenclature concern this is from the SunTouch website, even the manufacture calls it 'radiant heat'.

" WarmWire™ floor heat cable is an economical way to utilize a radiant heat flooring system as a means of warming floors. This floor warming system offers underfloor heat that helps keep bathrooms, kitchens, and entry ways dry and safe."
 
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Old 03-27-09, 10:06 PM
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Yes right about the thinset. You can use either of those under Ditra. I believe Custom does not make Master or Premium Plus anymore. They only make Custom Blend, probably because HD wants the cheapest product for their shelves. No one here will recommend using Custom Blend, it is not so good.

Go to a real tile shop for a high quality unmod, It would be nice if you could find Ditra Set near you. Lowes carries a better unmod if there's no Ditra Set available.

As for the span, we'll also need to know the species and grade, otherwise we guess.

Jaz
 
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Old 03-28-09, 07:42 AM
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As an alternative to your method, consider using self leveling compound. You will get a dead flat floor which is what you need to install the ditra. Trying to scread the thinset flat enough to install ditra is no easy task imo. Your bathroom is small, so the cost of slc wont be all that much.

What ever method you use, stay away from the cheap thinsets available at HD. Since you are doing this yourself, you can afford to get good quality setting materials.

As Jaz mentioned, you can get good setting materials at a real tile store. With thinset, you generally get what you pay for.
 
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Old 04-06-09, 07:28 PM
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In a jam

Well, I made a BooBoo ( with capital B's)

I ripped up all the old floor, 1 layer of vinyl and and 1 of laminate hardwood.
Laid down 3/4 plywood, and laid the warming wire.
On close examination I found to floor to be unlevel, by about 3/4 to 1 inch, in a 5 foot span.
SO, I took Johnny's advice, got myself some SLC ( other advice from this link : SLC & Radiant Heat Flooring where consumers & DIYers come for answers and flooring professionals help each other ) and poured a new floor. I used plastic lathe, roofing nails ( lots of em) and primer)
All went well, until I realized I poured too much SLC. It wasn't clear until I poured the stuff just how unlevel to floor was. So, I removed as much as I felt I could before it set up.
NOW, it's all set, and the SLC is 1/4 deep on the thin side, 1.5 inch on the thick side.

I got two problems:

1) the floor is too think, and the warm wire will heat unevenly. one side will be warmer than the other. I called the manufacturer of the wire, they say 1.5 inches is about all it will penetrate.

2) the floor is to high. at the door way to adjoining room, it's already 1/8 to 1/4 higher. once I add thinset and tile, I'll have bout 1/2 inch. plus if I were to use ditra as planned, it will be 3/4 inch higher.

Solution 1: live with it, tile it, and forget it. The wire might be ok, but I can't test it for 28 days, till the SLC cures fully.

Solution 2: add another warm wire on top, then tile it, this solves problem 1, and makes problem 2 worse. I can raise the carpet floor a little, with a small shim under the pad, but it will be obvious.

Solution 3, rip it all up, re-pour to only 1/4 as think, let it dry, add warm wire to semi level floor, then pour another 1/4 thickness.
This should make it half as thick overall, and have the wire at an even depth. Then tile as normal. Down side is $400 of material, and 3 or so more days of labor.

Currently I change my mind about every hour which is the best option. However, I think that the SLC is not fully hardened yet, so if I decide to rip it up, sooner is better than later. It's cured bout 24 hours so far.

Does anyone have experience with warming wires on nonlevel floor under SLC? Was performance ok?

Whats the best way to remove SLC? ( I assume cut it into small sections with diamond saw, and use a larger crowbar/small impact hammer to detach it from subfloor)

Any advice I haven't thought of?

((Note to self: Remember, Your doing this yourself because you have pride of craftsmanship, it's FUN, and you ENJOY working on my own home ))
 
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Old 04-09-09, 09:55 PM
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well, slc is now 80% out.
Now I'm back to deciding how to level the floor. Since the highest spot is only 1/4 inch lower than the door, any slc/ditra/tile combo I add will make the finial floor higher than the adjoining floor at the door.
If I didn't need the 5/8 plywood over the TG boards, it wouldn't be a problem. I wonder if SLC would be enough support, without the plywood.
ATM, I leaning toward raising the floor joists at the foundation.
 
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Old 04-11-09, 11:35 PM
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in case anyone is interested, an efficient way to remove SLC after it's set is by cutting it into 2 foot squares with a diamond blade in a skill saw, breaking that into smaller pieces with an air hammer, and finial cleanup with a 4.5 inch diamond blade in a hand grinder. After all is done, back to bare plywood, good as new (almost). A shop vac helps keep the majority of dust down. Eye, ear, and lung protection is a must.

I've now poured a new layer of SLC, apx 1/4 inch, feathering to 1/16.once that dries, i'll lay the heat wire, prime it again, and pour another 1/8 layer. Then all set to tile
 
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