# Bathroom floor on Pier and Beam



## dw8 (Oct 2, 2011)

In my part of the country we normally have slab on grade.  This is my mothers home which is one of a few pier an beam homes in this area.

Original floor was:
Sub-SubFloor  - 3/4 inch T&G pine layed at right angles to beam
SubFloor - MDF with 1/8 inch plywood laid on top.
Finished Floor - tile.

Where I'm at.  
Cut flooring down to Sub-SubFloor at all wall plates (FWIW used an oscillating saw) and removed all damaged flooring.
Sub-SubFloor is bowed and cupped in places and appears to have 15 or 30 lb tar paper
   sticking to to a number of boards.
Sub-SubFloor boards appear to be structurally OK, as well as the joints, but does appear to be water stained.

Questions:


> 1)  If water stains are from toilet (likely) can the Sub-SubFloor be saved or does it need to be replaced?
> 2)  If saved, what is the best course of action?
> (a)  Wash boards with a bleach solution and what about the piers?
> (b)  Saw those boards that are cupped / bowed and renail?
> ...


Thanks
David


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## BigChuck (Oct 2, 2011)

I'll need a good Boston handyman when I move, but sorry I don't have the answers for your questions. Perhaps make a post in the general?


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## BridgeMan (Oct 3, 2011)

Hard to answer questions or suggest repair procedures without seeing a few pix.  Could you post a few?


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## dw8 (Oct 3, 2011)

Thanks for responding.
Will take a few pix tomorrow am and post this thread.


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## dw8 (Oct 3, 2011)

Pixs attached.   
Tried to show cupping and bowing in boards but didn't show well.
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You can see staining on the boards(pix2), so question still exists do boards:
1)  Need to be bleach treated, 
2) some other product, 
3) or All removed and new sub-subfloor installed.
    If new sub-subfloor, how should floor joists be treated?.
---------------
You can see the tar paper adhering to the boards(all pixs_.  Really stuck on.  The black you see is the tar paper --NOT-- mold.
-------------------------
Plan on replacing the boards around toilet flange.


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## nealtw (Oct 3, 2011)

Poke at it with a screw driver and compare it to boards that appear to be in good condition.


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## dw8 (Oct 3, 2011)

As previously posted, boards are structurally sound.  Tested with awl.
My  primary issues are:
1)  Since toilet water -- should boards be treated in some manner (bleach for example) or will using bleach cause nail corrosion and potential problems (boards loosing because of nail giving way) down the road?  
2)  Making sure all bows and cupping in the Sub-SubFloor are handled so no floor squeaks occur later on -- what is "best" solution other than new Sub-sub floor.


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## nealtw (Oct 3, 2011)

If the wood is solid and has no signs of mould I wouldn,t worry about it. Bleach if you want, it won't hurt anything. For the joists and members below I would use a copper based treatment. As far as the cupping, you do want to get it flatter, if sanding just set the nails deeper. I think I would be taking out the bad stuff and putting in plywood as you are changing some anyway.


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## dw8 (Oct 4, 2011)

nealtw:  Thanks for responding.

Leaning toward ripping out and going back with plywood for sub-subfloor
By the time I set nails, sand, and mess around trying to determine if everything is level
I believe I can get out the entire old floor and replace with new.  Will have to double-check on
one joist to make sure it is available for nailing at one end of the bath.

Not familiar with "copper based treatment" ?   Years ago - I believe - they used to
soak wood with copper for termite protection (I believe they use glass impregnation now).
Is this why you recommended the copper?


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## nealtw (Oct 4, 2011)

Homax Group Inc 61250 Gallon Green Preservative


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## BridgeMan (Oct 5, 2011)

Copper napthanate is the good stuff, strongest that can be purchased/applied by laymen without a license.  But I suspect, way overkill for your situation.  Replace the subfloor if that's what it takes to make you sleep better at night.  Me, I'd look at a less labor-intensive approach, as in just giving it a shot of bleach, then filling in any low spots with Duroc water putty and sanding smooth before putting down the new floor surfacing.


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## dw8 (Oct 5, 2011)

nealtw and BridgeMan:
Thanks for feedback. 
Did some checking about copper preservative.  WIKI had a great writeup.

To complicate matters more, the crawl space under the house is actually a closed plenum
that is used for heating/cooling since this originally was a solar home.  Years ago when
termite treated, they used a borate solution - instead of copper - over concerns of potential health
effects other insecticides might have.   Doing some more research on this today.

BridgeMan:  "Duroc" hadn't even thought of that.  Have seen it in small cans (in fact I have a small can of the stuff), but for a floor I would think you would need to buy it in 5 gal buckets


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## BridgeMan (Oct 6, 2011)

I've only used Duroc for localized leveling (small areas, less than a few inches by a few inches, or less).  Wouldn't recommend it for leveling large areas--best to use bagged floor levelers for that (cementitious products you add water to).


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## dw8 (Oct 7, 2011)

BridgeMan:  Thanks for feedback.  Familiar with self-leveling compounds for concrete.


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