06:08PM | 03/19/05
Member Since: 03/04/05
33 lifetime posts
I have a rotten spot of wood in the bathroom subfloor in the corner between the tub and the toilet. I pulled out some of the wood (with my hand...) and now there is a hole in the floor. Evidently, there was no underlayment between the subfloor and the cheap vinyl tile squares. Not sure how this spot rotted so badly. I had a leak in the tub drain and I believe the fridge in the kitchen (other side of the wall) could have possibly leaked although the damage from under the house looks more like the bathroom. At any rate, based on my research I think I need to use 2X8's perpendicular to the joists (attach using deck screws?) and patch the hole up to the wall with 1" plywood. Should I also take out the vanity and toilet and put some kind of underlayment before I top with some faux stone laminate? Any tips/suggestions are appreciated. Also anything on reinstalling the toilet and vanity - rather not mess with the tub if I don't have to.



04:16AM | 03/20/05
Member Since: 01/30/05
361 lifetime posts
Dear Tally (I'm wordy so this will end-up truncated, click the link at the end or below your view that says "view entire message):

First of all, you state "Not sure how this spot rotted so badly. I had a leak in the tub drain."

Are you sure you have corrected the only leak? If you repair this now and caulk well and you still have a leak problem, you're only going to hide and seal up this water to cause even further damage that won't evidence itself until its too late. At the end of this I'll throw a list of things to investigate for leak sources (sneaky leaks that only leak when you're not looking), but there's always the obvious thought that someone isn't protecting the area adequately with a shower curtain.

Secondly, regarding deck screws, I wouldn't use them. I suggest for such a wet area, where removal/repair in such a wet environment of a bathroom being so likely, and errosive/corrosive effects on screws at their most extreme

to use STAINLESS 18/8 Metal screws with flat topped phillips heads. At least a #10, possibly #12, but I think #10 head will be perfect for your application. Since you have to screw into the floor joists and blocking material, I'd suggest at least a 1-1/2 screw, but you might want to go with 1-3/4 or 2" if you can find them. They are just like "brass wood screws" except they are threaded all the way up to the head. Be sure to drill pilot holes as recommended on the screw box, usually a #10 requires a 9/16th pilot hole. Mark your drill bit with some masking tape at the length of the screw so you don't "over drill" this is quite important when doing this on structural members, and as you never want to penetrate beyond the one-third mark from above on these floor joists as that will weaken their structural integrity, and you are kind of weak already with 2x8's at 16" OC. Do not try to counter sink these beyond flush or just a scant below flush, as to do so will bust the fibers in the outer ply of the plywood thereby reducing its strength. Use the same screws I mentioned or longer if necessary to secure the flange ring for the toliet to the replaced sub-floor in that area. If you can find these screws for a No. 1 bit or a regular screw head that would be even better, but usually the "box stores" only carry #2 phillips head for these screws.

Third, the outer edge of your tub is one of the heaviest load points on the drain/service side. Generally when tubs are installed they are not level, but pitch towards the drain and away (high) at the walls that are NOT the drain sides. your seams in the sub floor should be centered on joists but NOT the joist that suppports this tub edge, (in fact there SHOULD be a double joist that runs the length of this tub on the long outside side. You really want those joist edge seams 2 joists away from this major stress edge if at all possible if in the traffic area of the room, or you'll have flex problems in the traffic area messing up your floor finish and squeeks.

Most likely your partition "plumbing wall" is applied ontop of this subfloor and the rot may have broadcast under that wall plate. You really should consider opening up that plumbing wall a bit near the floor from the oposite side of the wall from the tub side and investigate the area there for damage, and/or leak sources.

for blocking the perpendicular sub-floor seams you can use 2x4"s toe-nailed to the floor joists from below, layed with the 4" side flat against the lower face of the subfloor, then stagger your screws about 3/4" OC in from the edge of the subfloor on either side of the seam and about 2-1/2" OC apart. This way you'll not have perpendicular flex between old and new.

I'm guessing your home is mid 60's to mid 70's construction as you mentioned 2x8"s and plywood subfloor, as in older homes you usually see dimentional lumber sub floors layed with staggered butt ends 45-degrees from the floor joists, and later homes beefed up the codes to 2x10 joists 16" OC. You might find that you actually have 2 layers of 1/2" plywood for your sub-floor/floor under the tile (cheaters method) or you may find that the lower (closer to the floor joists) layer is 5/8" plywood then dressed with 1/2" layer, as mid-60s required minimum sub-floor 5/8", or if transitioning to like tounge and grove hardwood elsewhere, you might see 2 layers of 1/2" ply or a 1" ply so that with the addition of tile, it is the same height of like hardwood in the hall outside the bathroom.

Third: possible hidden sources of leaks:

1) Assuming this is a tub/shower combination situation, the tile grout or surround seams may have failed, allowing water behind it, running down the inside to the flange/mounting edge lip-edge of the tub, that then travels down to one of the corners, then drips off and runs along the sub floor under the tub to just inside/under the tub at the area you see evidence.

2) weakened area that allows the structure and/or tub to flex when in use that allows a leak situation only when stressed (like when someone standing in it for shower, or the tub filled for bath and/or with addition of person

3) the caulk seal between the tub lip and the wall/tile/surround, allowing water behind, traveling to the lower corner, dripping on the subfloor, and running along the surface of the subfloor to the point you find the damamge.

4) the overflow/drain assembly, often the overflow escutchen gasket (rubber) fails overtime, allowing water behind it, running on the outside of the overflow and onto the subfloor.

5) mixer valve/water handle escucheon plates not being sealed/caulked or the caulking failing that's behind it

6) leaks in the mixer valve or plumbing in the wall servicing the tub/shower

7) someone who shall remain nameless not securing /overlapping the shower curtain properly, and water running out the tub and onto the floor while in shower use or excessive splashing/playing while in the tub

8) As a tub is not set "level" but with a pitch toward the drain, so are all the exposed rim of the tub, so the site of the drip damage is not always the location of the LEAK/invasion from the wall zone above the contained tub.

9) if the floor is pitched from the toliet down to this point at the tub could be a leak from the toliet? that runs on top of the tile and terminates there?

I'd open the oposite wall so you can see there view with a mirror and flashlight, view again with the tub filled (heavier each gallon of water adds about 7 pounds), then get a volunteer to stand in the full tub, using a level on the floor, see if you're getting flexing/additional pitch when the tub is loaded. Do the same test with a volunteer sitting on the toliet seat AND flushing both with dry tub and full loaded tub, then investigate the overflow/drain assembly's connection to drain/vent see if that flexes and shows a leak when "weighted". Next have someone direct the shower spray at the plumbing wall while standing IN the shower loaded weight while you investigate see if you have a flexing issue there regards to the overflow and/or drain and escutcheons.

most likely the water rot has broadcasted outside of the tub now, but started under/inside the tub, and that area will need to be repaired as well, or you'll just have mold/rot issues continue just hidden until the problem is worse. You need to identify the source of this water and correct THAT first. Also I'm concerned that your plumbing wall is constructed ON TOP of this subfloor and that the rot may be under that plate as well, please check as if this wall is effected you have more work to do, as if its resting on rotten wood, that wall will flex and you'll always have a leak situation between the tub and this tile on this line or where the back wall meets this wall on the inside of the tub.

I hope I was clear with what I wrote. Please advise if I wasn't and also let us know what you found.

Good luck and best regards,



01:20PM | 03/20/05
Member Since: 03/04/05
33 lifetime posts
Ell-thanks for all the insight and sage advice. I believe that the bathroom floor problem came from water out of the tub/shower and possibly a toilet leak. From under the house this afternoon I could see some water marks coming from where the toilet sits. I also noticed drops of water coming down the toilet drain pipe and the back side of the tub. I have recently caulked around the tub spout (but I mistakenly left the hole on the underside of the spout uncaulked... should I caulk there too?) As you can tell, I am admittedly a beginner at home repair. I think at this point and based on your reply, I have a problem with the toilet drain and the caulking around the tub and grout in the tiles.

A little more info on the subfloor foundation. The space in between joists is actually 22" (I measured this afternoon). When you said I was already on the weak side at 16", I cringed. These are 2X4's with the metal V connector pieces attached to another 2X4. This is a townhouse built in 1986.

How am I supposed to install these additional supports in between joists? The 2X4's lay with the 4" along the floor, am I to drill through the entire 2X4 to reach the perpendicular support? Somehow I doubt it, but can't think of how to attach.

The floor joists run perpendicular to the tub and there is one that I can touch through the hole and another one almost to the back of the tub. You are correct and the plumbing wall is ontop of this subfloor. I pulled away a bit at the bottom and can see the wall. It's not wet and I don't really know how to tell if there is damage. On the other side is the range, a cabinet and then the fridge. There are two different woods I can see from underneath, the original 1" on the bathroom side and then a newer on the kithcen side. The old fridge also had a hole in the condenser bowl (I could see that it had been patched) that may have leaked on that side.

I am getting a little frustrated at this point, only because it is an area that I do not completely understand. I am on a budget, but don't mind doing the labor myself as long as I know what I am doing. From your reply, my mind has now shifted to the tub... Even with the toilet and vanity/sink out of the bathroom, how in the world would I get that tub out??? Am I going to have to retile the whole enclosure? I am one who tends to prefer to handle one thing at a time, but with issues like this, I understand everything must be considered. What will be the first (of many I am now sure) to correct this bathroom problem? Your patience is appreciated as this beginner is eager to learn and to resolve this "issue". Thanks again.

Best regards,




01:21PM | 04/05/05
Member Since: 03/04/05
33 lifetime posts
Ell- I have been thinking about the best way to do this and I am still confident that I will be able to do this myself. I am wondering about what you said about the wall... The wall does appear to rest on the floor in this area. However, the joists run perpendicular to this wall. Am I supposed to move the kitchen cabinets in order to lay new plywood over the two joists (there is one in the bathroom and the other is in the kitchen)? Or can I install blocking between the joists for the wall to sit on?? Part of the subfloor under the tub (in that corner) has been cut away. I don't know when, possibly by the plumber I hired to fix the leak in the tub drain. Is it necessary to replace the subfloor in this area? Or will the blocking under that edge of the tub be enough?? I have noticed (from under the house) that there is a drip from under the toilet. I can't tell if it is coming from the flange (wax seal??) or from where part of the connecting pipe has broken away. Other than re-caulking the tun, I can't think of where else I would be leaking. What are your thoughts?



04:51PM | 04/06/05
Member Since: 01/30/05
361 lifetime posts
I didn't mean to ignore you tally, somehow I missed an email from the board that you had re-posted.

Okay, good news is that the floor under the tub isn't wet (apparently).

I'm confused though, you went to the basement, found the floor joists (ceiling of the basement) under the bathroom were 24" on center but only 2"x4"'s? are you sure about that? because now i'm really concerned. lets hope that was a typo or you were referring to the blocking between the (hopefully) at least 2x8"s or possibly 2x10" floor joists.

The floor joists running 90-degrees to the tub edge is okay, but when you patch the floor up to the edge of the tub, you'll have a problem "marrying" that edge under the tub by putting a flat 2x4 under the sub-floor overlapping the old edge and the hole, drilling from top of the sub-floor thru it and into the 2x4 on the 4" side, then placing the sub-floor patch over the hole, and drilling screws thru it onto the "lip" edge of that 2x4" we just discussed installing.

make sure your seams going the direction of the floor joists are right on the centers of those joists (leaving 1/2 covered by the old "good" floor) and screw in both sides of that seam using a staggered pattern.

I'm kind of caught up about the idea of 2x4 joists laid flat...that would mean your joists are only 1-1/2 (2" side of dimmentional lumber) high.

Get back to me on this one...A.S.A.P. I think i'll be having nightmares. Is this a manufactured home?


05:05PM | 04/06/05
Member Since: 01/30/05
361 lifetime posts
you mentioned some part of the toliet pipe/connection being cracked.

not sure which part you mentioned was cracked...the flange on the bottom of the toliet that seats onto the wax ring that seats on the plumbing pipe flange, the pipe itself? That cracked thingy what ever it is (base of toliet, waste pipe flange, or waste pipe) needs to be replaced, a nice new wax seal installed and toliet re-set. if there's rot issues there, best fix that floor there as well before re-seating toliet, but that's something needs to be addressed a.s.a.p.

I had a tiny leak around a toliet when my kid was little. One day she flushed and it didn't quite do the job (she clogged toliet - prolly too much paper), so instead of calling me she flushed a second time (bowl hadn't quite drained from the first time) and whoosh the wax seal blew out...and what a mess..turned out my stack pipe (waste pipe) flange was broken...what a yucky mess.

I take it you have a tub, and tile around it.

IF you end up having to pull out the tub, you could get a dremmel tool and remove the grout around the lowest 3 or 4 rows of tile closest to the tub, then remove those rows and cut back the wall to expose the tub flange (lip) to free up the tub. Most of the tile will end up breaking for sure when you go to remove it, but its less tile to replace later. Then when the tub goes back in (its a fight) possibly save you some repair work.

Do you have a local "handy man" you might call in? pulling out and setting a tub is not a one-woman job for sure! frankly its a 2-3 man/woman job (because you need someone below directing alignment to the drain pipe. Since you recently had a plumber in to address a leak in the area previously....perhaps he'd be willing to return for a peek (suggest his prior repair might be leaking maybe? -- hee hee).



05:28PM | 04/06/05
Member Since: 03/04/05
33 lifetime posts
Ell-Good to hear from you and thanks for the advice. I am in a 1986 frame townhome, built off grade with an open crawlspace, no basement. It is not a manufactered home, however, the floor joists are made of two sets of 2X4;s, 24" (OC?) vertically connected by these metal V connectors. So yes,they are 2X4's but there are two of them that sit about 8" apart. Should I be having nightmares about this??? I hope not. Sorry if I am not being clear about the joists, but let me know if I have not explained...

I was considering pulling up the most of the floor, but at least the front half that encompasses the hole and the toilet, which from underneath appears to have leaked onto the floor at some time (water marks running away from the toilet).

Will it be a problem to run a 2X4 flat between the joists underneath the edge of the tub? Will I need to run another 2X4 for the bottom of the joist? Please let me know if you know what I am talking about with the metal V stuff... DO I need to connect the blocking with metal V stuff?

Also, after I have replaced the subfloor, I wanted to install durarock on top and then maybe tile. Should the vanity and toilet sit on top of the plywood subfloor or the durarock or tile???

Everything I have read says make sure you have carefully planned your project before starting, so I hope I have given myself enough time. I appreciate your patience, as I am only a beginner. Thanks!



07:40AM | 04/07/05
Member Since: 01/30/05
361 lifetime posts
okay...these would be perpendicular in orientation to the joists...not secured to the joists between the joists.



the [] being cross sect of the floor joists

the --- being the subfloor seam

disregard the .....'s they are for spacing.

the ===== being subfloor edges both sides

each side being over half of the side of the flat 2x4 and that 2x4 is centered under the seam from the crawl space side.

From what your saying I'm imaginging

that you have 2 each 2x4's, stacked ontop of each other that are held on top of each other by metal strapping so its trying to create a 2x8"? so if each ===== is a 2x4" and you look at the side view of a joist facing it it looks like this?

______________ sub-floor

============= first 2x4

============= second 2x4 under

open crawl space below.

is that right? and that they are strapped on

the side faces (4" deep side or rather 3-1/2" side)like this:

....____________ sub floor above

....[]\__/\__/\_ [] is top 2x4 sits on top

....[]_\/__\/__\ []lower 2x4 with /\ strap

..................crawl space below

Is this what you're indicating?


07:52AM | 04/07/05
Member Since: 01/30/05
361 lifetime posts
or are the 2x4's sitting on top of each other on the 4" side and strapped together simulating a 4x4 post? Like this

===== sub floor

[___] first 2x4" with 4" side to floor

[___] second 2x4" with 4" side to above 2x4" crawl space below.

Also a little education, you mentioned before that when you measured between the joists the "space" was 22 inches. the measurement is "on center" that is needed. you can achieve this from measuring from the left edge (crawlspace floor side) of one joist to the left edge of the adjacent for the OC (on center) spacing, or

from the center point of the "thickness" of the joist to that same center point of its adjacent (next over) joist. That gives you the OC spacing. Another way is to measure the "space between" the joists plus add the measurement of the "thickness" of the joist, that is to say the edge that is opposite the edge that TOUCHES your sub-floor.

Then do me a favor, and tell me the measurement from the "ceiling of the crawl space" or the point where the joist top touches the subfloor down towards the floor of the crawlspace where the joist ends (height of the joist NOT the distance to the crawlspace floor) does this make sense? think of the "side" of the joist as a wall I need to know its "height" is it 4" (3-1/2) or is it 8" (7-1/2") "high"? total with this v-strap system that "marries" the 2 each 2x4"s together. because I'm still somewhat confused as to what you were describing earlier.

doug seibert

08:04AM | 04/07/05
Member Since: 08/10/02
842 lifetime posts
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