Bathroom Floor repair

[Psycho0124]

The family and I currently live in an older wood-framed home circa WWII era (it was once on-base officers housing that was moved into town after the war). Over the past few months, a problem has been brewing in the bathroom which all began with a small water leak in the wall behind the lavatory. The leak was repaired but the floor in the bathroom just behind the toilet had become water-logged (fiberboard subflooring from a previous shady contractor) and the flange on the toilet was cracked. I removed the toilet and repaired it as best I could but the problem continued and now the bathroom floor is soft and cracks have appeared in the vinyl sheet flooring.

Heres the plan:
After removing the toilet and vanity I will tear the floor down to the beams and see what condition everything is in. If there is water damage on the beams (i suspect one or more may be sagging slightly) I will sister on 2x6" beams using construction glue and 3-1/2" screws (with pilot holes and in a staggered pattern to prevent cracks). I intend to use a hydraulic car jack and some bricks/lengths of 2x4s to carefully bring the damaged beams back into level before reinforcing. I will probably replace all the cross-members under the toilet with CCA treated 2x6s as well.

The flooring material I intend to use is two layers of 3/4" CCA treated plywood (construction glued to the beams and between the layers and nailed in place). The beams are 13" apart on center (odd I know) so the floor thickness should be sufficient. Once the demo and re-flooring is done, I will fill any anomalies in the flooring with wood-filler, sand smooth, clean thoroughly and put down vinyl tiles to complete the job.

I have done some floor repair and framing in the past but this will be the most in-depth repair I have done. I guess I have a few of questions about the job..
Are there any foreseeable problems with my plan?
Are the vinyl adhesive backed-tiles going to adhere to the treated plywood?
We have a 3-year old son. Using CCA (copper, cyanide, arsenic) treated plywood flooring, are there any health concerns for our son once it is covered with vinyl tiles?

Sorry for the wall-o-text and thanks for any tips/advice you might have! P.S. The forum seems to ignore formatting on this post. Whats the deal?

[pushkins]

What "cross member" under the toilet are you referring to ? there should be the floor joists and thats about it.

Your plan is good except if it were me I'd be bolting the sistered joists, tat is a much stronger way.

Don't be cutting the CCA or CCQ or any treated lumber around your little fella, but once it is covered there should be no problems.

The best way I'd see would be to use the 3/4" CCA/CCQ as the sub floor covering then use a standard grade floor covering of ply, this would be a much better base for stick on tiles.

[Psycho0124]

I am not much of a carpenter so I am sure my terminology is way off. Sorry for the confusion. By "cross members" I meant the short 2x6"s that connect the beams on either side of the 4" toilet line to form a box to support the toilet flange. The toilet is a full 2 inches lower than the rest of the room at this point so they must be in poor condition.

Your right I think about bolting the sistered 2x6"s. Maybe some very large washers on either side to distribute the compression load on the wood. I'll pick up the hardware this evening.

Also would you consider 3/4" treated ply to be an inferior sub-floor? Really what I am shooting for is a drastic over-engineering of floor strength. The wife is not a small woman and she has a tendency to dash into the bathroom and dive onto the toilet at the last second (which is why the flange was cracked and leaking).

Is there perhaps a covering I could put over and glue to the CCA stuff to help with tile adhesion? I suppose I could leave it exposed for a while and let it dry out some before applying the tile. This kinda brings back the health concerns with our son though.

Thanks for the tips by the way!

[pushkins]

No you can use the pressure treated ply for the first layer of sub floor then screw to that a layer 5/8" sheet of Advantech, just as strong and made for floor adhesion and for the application you need.

If you still want to use the double layer of CCA/CCQ then add a 1/4" layer of flooring ply before you lay the peel and stick tiles.
Don't forget though you should also use a "primer" before you lay the tiles, you can get it in any of the bog box stores in the flooring department.

There is no real reason to replace the "cross members" around the toilet flange, the floor joists and the "double" layer of floor sheathing is way more than enough.

[mrcaptainbob]

Why is treated wood preferred for this application? I thought treating was to keep from being infested. Should be no infestation indoors. I would think untreated pine 2x's and sheet wood would be fine. I did similar in my place with a double layer of 3/4 ply on top of sistered joists. Sisters were glued and through bolted every staggered 18". Solid like a rock. If I do another, though, I'll lay the first layer diagonal.

[Psycho0124]

Originally Posted by mrcaptainbob

Why is treated wood preferred for this application? I thought treating was to keep from being infested. Should be no infestation indoors. I would think untreated pine 2x's and sheet wood would be fine. I did similar in my place with a double layer of 3/4 ply on top of sistered joists. Sisters were glued and through bolted every staggered 18". Solid like a rock. If I do another, though, I'll lay the first layer diagonal.

I opted for treated lumber for a couple of reasons:
I live in a tropical and highly humid environment to begin with (south Texas only one block from the shore). In a bathroom environment, there is even more possibility of moisture exposure. It may be a little more expensive ($46 a sheet) but treated 3/4" provides near immunity from moisture and excellent longevity. It is also highly resistant to terminates which are also prevalent in this climate.

Plywood, if I understand it correctly, is just a glued sandwich of alternating grain sheets. How would it help to lay it diagonally? It seems like this would require far more wood to get the project done.

Originally Posted by pushkins

If you still want to use the double layer of CCA/CCQ then add a 1/4" layer of flooring ply before you lay the peel and stick tiles.
Don't forget though you should also use a "primer" before you lay the tiles, you can get it in any of the bog box stores in the flooring department.

There is no real reason to replace the "cross members" around the toilet flange, the floor joists and the "double" layer of floor sheathing is way more than enough.

Would a sign-quality oil-based primer work on the floor-ply or is there a specific primer for this application?

Floor height is going to be a concern if I add something on top of the 1-1/2" of flooring. I guess a small step up into the bathroom is a small price to pay for the peace of mind and the ability to park an M1-A1 Abrams Main Battle Tank next to the vanity.

Is there another type of flooring that would be better suited to the treated plywood?

I really appreciate all the advice! Having a couple (more experienced) heads to run the project by has really helped a lot.

[HayZee518]

I don't think you'll go wrong with pushkins advice. He's up on top of it - captbob has been through the mill so to speak also but he's in michigan. good advice from great people! - hayzee

[pushkins]

The primer your going to need is a latex based primer specifically for treating of sub floor prior to laying vinyl of any description. It will be in the flooring department. Armstrong make one that I can think of and it should cost about $7 or so.

[Psycho0124]

Well the demo is finished. It turned out to be a mix of old mid-1940s slats covered with plywood for about 8 inches on one side. The rest was plywood covered with ruined fiberboard. The slats looked to be fine and ended on a joist so I think I will leave them. They will be covered with another layer of high quality 3/4" anyway. The floor joists themselves turned out to be 2X10s and looked to be in wonderful shape even around the lavatory!

I ran into 2 problem areas with the flooring though. One side of the room has a fiberglass tub/shower combo. Both layers of (good) plywood run underneath the tub but there is some dry rot on the outer end where it meets the joist. I went ahead and cut everything back to 2 inches from the tub on the bottom layer of ply (sheathing?) and about 1 inch out on the top (subfloor). There are beams running perpendicular to the tub every 13 inches but I think I should hang some 2X6" joists parallel so the ends of that ply rest supported.

Also there is a water heater in the room enclosed in 1/2 plywood walls. The floor inside is in decent condition as there was no vinyl covering to hold in moisture. There is some overhang on the bottom side of it as well as a lack of support on the right that has me concerned so I am thinking of adding some joists here as well.

Here is a quick little diagram to show the condition of things:


Will this provide enough support for everything?

Also for the final floor prep, I am going to fill any voids/irregularities with "Well-Cote Water Putty" and glue+nail down a sheet of 1/4" floor ply on top of that. Would the peel-stick tiles adhere to a coat of spar varnish (more moisture resistance (and I have a gallon in the shed))?

[mrcaptainbob]

Ahh...Texas and termites. I'd use treated products also! (Our daughter and three G'kids are here for a month from San Antonio. They're talking like 70*'s is chilly weather!) Glad to hear the joists were in good enough shape. Sistering is such a pain!