# Replacing T&G OSB subfloor panels?



## I.M.O.G. (Jul 28, 2013)

Not sure if its within the scope of WWT, but you folks have been helpful so figured I would put it out there.

I've got a smelly room in the new house. Pulled out the carpet and padding. Found some mold between them, with moisture damage to the subfloor. House was built in 2000, and used T&G nailed down OSB subfloor panels - not sure on the thickness. No signs of water damage or repair in the ceiling, house had been foreclosed, then upgraded and flipped - guessing either a pet or angry evicted urinated in the room.

So anyway, naturally the spot is on a seam, and affects about 3 panels. I'll need to rip them out, and replace with new.

I don't know how to remove the subfloor panels since they are tongue and groove - crowbar and prying would likely destroy the tongue on currently undamaged panels. I was thinking of making two diagonal cuts on each panel, then prying up from the center?

More importantly, my concern is how to install the new panels? With the tongue and groove, I won't be able to just drop a panel in. From what I had read, I could just trim off the bottom lip of the groove, which would allow me to slide in the tongue on the opposite side, and what's left of the trimmed groove would just drop into place. I don't know how advisable this is.

Any advice? Only thing I'm sure of is running an extension cord to power the circular saw, and ensuring power is off to the room, just in case I would knick an electric line.

Input or thoughts appreciated. Apologies if this isn't the right place, or if I should take this question to a diy forum.


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## Steve Neul (Sep 2, 2011)

Gee's, I wouldn't pull out the subfloor because of some odor. I would thoroughly clean it and paint it. The paint will seal out any odor the wood may have. Use a latex gloss or semi-gloss house and trim paint. The glossier it is will seal better than flat.


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## I.M.O.G. (Jul 28, 2013)

OSB doesn't cope well with moisture damage... the urine smell is soaked deeply in, and there was also mold in the carpet/padding. Due to gross factor, as well as safety for kids who could be crawling there one day - I don't want to play any games with it. Plus, on a hot day the paint likely wouldn't be good enough, and a slight scent would bake out sometimes. Covering it just is a bad idea, sorry.


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## JohnK007 (Nov 14, 2009)

How big a section are we talking about? If not the entire room then you could cut out the damaged sections making your cuts along the joists then nail cleats to the joists and nail the new sheet material to the cleats. Toenail additional cleats across the joists to provide a nailing surface between them. Use construction adhesive and nails. This is pretty much how they sheathed the entire subfloor of my house addition.


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## GeorgeC (Jul 30, 2008)

I.M.O.G. said:


> Not sure if its within the scope of WWT, but you folks have been helpful so figured I would put it out there.
> 
> I've got a smelly room in the new house. Pulled out the carpet and padding. Found some mold between them, with moisture damage to the subfloor. House was built in 2000, and used T&G nailed down OSB subfloor panels - not sure on the thickness. No signs of water damage or repair in the ceiling, house had been foreclosed, then upgraded and flipped - guessing either a pet or angry evicted urinated in the room.
> 
> ...


Your tentative procedure sounds good to me. 

Is this OSB the only thing on the floor or is it on top of another layer of something?

George


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## I.M.O.G. (Jul 28, 2013)

Thanks for all the input guys. Also sorry Steve, rereading my last post it didn't come off sounding the way I intended.

@JohnK007: Its a small section. Sort of large if I'm thinking of how big a spot I could make by peeing on the carpet and letting it sit, but not big. Maybe a few feet one direction by a couple feet across. It just happens to sit along a seem where a number of panels come together, which annoys me, as they could have at least hit the middle of a panel and made it a little easier on me. I suppose if you are urinating on the floor of a house you are getting evicted from, you aren't really considering these matters though.

I'm not sure how to ensure I'm cutting along the joists, or where the joists are - where the nails run those are easy to spot, but every joist doesn't have nails going into it. I've got a studfinder, so I'll see if that has the depth to shoot through the OSB and let me know where they are. I'm a n00b, so also bad on terminology, so when you say nail cleats to the joists I'm not entirely clear on application. I'm picturing a 2x4 as the cleat, nailed so that it spans the joists and helps supports the panel I'm installing? Or maybe parrallel to the joist, to give room to nail the board down to, without overlapping the tongue of adjacent panels sitting on the joist. Sorry, I think I need an "explain like I'm five" version. I have no pride - I used a circular saw for the first time a few weeks ago, and used a table saw for the first time last night. I'm learning but have no experience.

@GeorgeC: OSB is the only thing on the floor, I expect. House was built in 2000 and I suspect the carpet I pulled out was original - it wasn't pretty, even ignoring the urine part.


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## I.M.O.G. (Jul 28, 2013)

Here's a picture if it helps:


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## Deanr (Jul 29, 2011)

I would take your pry bar and put it in the seam and pry up one edge of the affected area to determine the thickness.

Then set the depth of your circular saw at this depth.
Plan on just cutting out the bad area.
Draw a rectangle just big enough to remove your bad area and cut this area out. Now you will be able to locate your joist and cut an area so the cut is on top of the middle of a joist.

On the part that is cut perpendicular to the joist you can screw a 2x4 nailer between the joist.
Then get the same thickness material and cut it to size and drop it in.
Screw down along the perimeter and any in between joists.

This way you use minimal material and don't worry about tongues.

Also if your saw is only set at the thickness of the OSB I woulnt worry about hitting any electrical.


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## JohnK007 (Nov 14, 2009)

Dean's explanation is pretty much what I was saying. Assuming the joists in your picture run up and down, you want to cut the old floor out wide enough to be next to or on top of the joist on either side. Using a cleat or nailer gives you a little wiggle room to attach the new panel. Some call this "edge blocking". This assumes they used standard 2X joists (2X12 or 2X10) and not I-joists which would make things more interesting as far as attaching an edge block goes. You can use screws or nails. The construction adhesive will minimize any squeaks. That's not that bad of a patch. Don't fret about the tongues.


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## I.M.O.G. (Jul 28, 2013)

Good deal. Thanks guys. I'm going to try straightening this out tonight, and I'll let you know how it goes.


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## Steve Neul (Sep 2, 2011)

The reason I suggested the paint is when my house was under construction I had an extra room that was never finished out. It just had the osb subfloor and the stud walls. My wife moved a dozen cats into the room and the entire room became a litter box. After a year with the cats in there we decided we wanted the room and moved the cats out and the odor was so bad in there I couldn't stay in there more than 5 minutes at a time. I just cleaned the floor and painted it and the odor was gone like there were never any cats in there.


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## I.M.O.G. (Jul 28, 2013)

Interesting. I'm kind of creeped out about the smell/mold and potential health implications, so I could certainly be going further than necessary.

Step 1 complete - create big hole in floor

That picture I posted above didn't actually quantify the amount of moisture well. Once I got a light in there and setup to draw my box around the square that needed cut out, the square turned out much larger than I thought. About 70 inches long, and about 54 inches wide. So its about the size of a bed. The noticeable part in the picture is just the worst patch, there are a few others where it looked like the puddle seeped out from.

The good news is, once the saw cuts were made, I had no problem pounding in a pry bar, breaking the glue bond, and pulling up the screws enough to work my way around without damaging the adjacent panels.

Step 2 in progress - scrape every joist, as almost all of them have glue/OSB fibers stuck to them. I suppose I need to get them scraped fairly well if I'm going to get the new board in there nice and flush.

Step 3 yet to come - I might square up my initial cuts, prior to cutting the board I'm putting in... I couldn't get the nails out until after I cut the box out, and in some places when sawing I worked around nails that were still in place as I didn't trust myself sawing that close to them. I'm not sure what happens if you hit a nail with a circular saw, but I wasn't going to find out.


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## firehawkmph (Apr 26, 2008)

I.M.O.G. said:


> Interesting. I'm kind of creeped out about the smell/mold and potential health implications, so I could certainly be going further than necessary.
> 
> Step 1 complete - create big hole in floor
> 
> ...


For step 2, if you have a heat gun, it will soften up the glue and make it easier to scrape off. 

Step 3- Squaring up the cut is a real good idea. Makes it much easier to cut your new piece. If you have a carbide tooth blade in your saw it will go right through the nails. Only way you'll know is you'll see a few little sparks when you hit it. The blades are made to cut through them, even the cheap ones.

Mike Hawkins


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## I.M.O.G. (Jul 28, 2013)

Unfortunately no heat gun... I've got a propane torch, but something tells me its ill advised.  I'll see how much trouble I have, maybe I'll borrow the wife's hair dryer if I'm having much trouble.

Good to know about carbide tipped blades and nails. Thanks.


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## Sleeper (Mar 24, 2009)

I had a Leaking Toilet and had to cut the Rotten Floor out. Mine was limited to the water closet, but this is what I did.









Oh I also used Bleach to clean up the mold and used a heater and fans to dry


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## I.M.O.G. (Jul 28, 2013)

Nice sleeper. I will post more pictures tomorrow of mine. I may use a little bleach on one of the joists that looks like it may have gotten moisture. Fortunately things look pretty good, but I will have a better idea once I get the joists scraped down.


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## GeorgeC (Jul 30, 2008)

Steve Neul said:


> The reason I suggested the paint is when my house was under construction I had an extra room that was never finished out. It just had the osb subfloor and the stud walls. My wife moved a dozen cats into the room and the entire room became a litter box. After a year with the cats in there we decided we wanted the room and moved the cats out and the odor was so bad in there I couldn't stay in there more than 5 minutes at a time. I just cleaned the floor and painted it and the odor was gone like there were never any cats in there.


If you are going to use "Paint" for this purpose, I highly recommend Kilz. It is designed to do jobs like that.

G


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## Sleeper (Mar 24, 2009)

I just wanted to clarify using the bleach. I had used the bleach or to be precise ‘Tilex’ for killing the mold. 

I didn’t have the Urine smell because I cut it all out but I had a neighborhood tom cat that used to spray my front door. I found that a zoo used peroxide in the lion cages so I tried that to remove the urine smell and it did work. You could try that as well


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## jschaben (Apr 1, 2010)

GeorgeC said:


> If you are going to use "Paint" for this purpose, I highly recommend Kilz. It is designed to do jobs like that.
> 
> G


In the paint world, Zinsser product called BIN is the gold standard for sealing off odors, sap or anything else emanating from wood or wood products. It is the preferred product for fire restoration also. It is basically a pigmented shellac and initially smells to high heaven when first applied, alcohol based. Smell dissipates pretty quickly but is very strong initially.:smile:


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## I.M.O.G. (Jul 28, 2013)

I've got 3 out of 4 exposed joists cleaned off. Didn't get much time to work on it today. Here's some pics of the progress so far:

















The top pic is just a hole shot. Hadn't done any scraping yet. Second pic was after most the scraping, you can see the joist in the back corner is clean there.

The board was there just for safety, to be sure I didn't take the express route to my first floor office. Made it easier scraping, which a cat tail works really great for with sufficient elbow grease applied... Looked thru my tools, and realized I had one so put it to good use.


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## nbo10 (Jan 26, 2011)

Deanr said:


> On the part that is cut perpendicular to the joist you can screw a 2x4 nailer between the joist.


What's a 2x4 nailer? Sorry for the newbie question.


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## JohnK007 (Nov 14, 2009)

You're on your way. No turning back now! :no:


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## Sleeper (Mar 24, 2009)

nbo10 said:


> What's a 2x4 nailer? Sorry for the newbie question.


 It’s a 2x4 board installed between the joists to provide support for the edge of the plywood or T&G subfloor. Otherwise the edge of the floor will sag if something heavy like a bed post or something is set on it. Nominally the Tong and Grove support itself but in this case there isn’t a T&G because it’s been cut off


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## I.M.O.G. (Jul 28, 2013)

JohnK007 said:


> You're on your way. No turning back now! :no:


Oh ya? Trying to talk my wife into just covering it with a bed!


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## I.M.O.G. (Jul 28, 2013)

And mission accomplished!

Thanks for all the advice. Not sure if I followed it exactly, but I took it into account and I've got a solid floor now with no squeaks... Except one corner of old wood by the door. Where it meets the new, it gives a little and rubs against. Shot some liquid nail in there, so I guess I will see how it turns out once that sets. Nothing else along that seam squeaks, and I didn't think of putting in any support in that area as its right between two joists.

Here's the hole all scraped and cleaned out:









Here's the support blocks I put in because this end wasn't ended on a joist due to the wall, so hopefully this will prevent sagging over time. One end of the block is on a piece of wood above the ceiling below, other end is glued and screwed into the joist.









And here it is finished. I'm happy with how it turned out. It helped a lot by cutting the insert into the right dimension, laying it in the hole, then tracing a line on the old floor where I needed to straighten out the circular saw cut to get it to fit. Went really easy.









Maybe not the biggest or hardest project, but not having used a circular saw before a couple weeks ago, I feel real good about getting it done. Thanks for the help, and maybe a little bit of extra confidence too that I could do it.


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## Sleeper (Mar 24, 2009)

Looks good


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## JohnK007 (Nov 14, 2009)

Nice job I.M.O.G. ! You have every right to be proud.


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