Bathroom subfloor complications, tiling, lots of pics, long post

With my bathroom demo came a lot of unexpected problems. This is just one of them

After demoing the concrete subfloor, I've discovered these wooden slats over the joists. I've also discovered all these crazy pipes running in between these slats. Some of these slats are not even supported at some ends.

I want to put down tile in the 5x5 area left over from the tub. I would have liked to remove the old slats and put down large sheets of plywood, possibly 3 layers of 3/4" T&G.

However, I don't know what I'm suppose to do about all the different heights of the pipes. I've though of laying down sheets of plywood cut out where the pipes are, then when there is enough height, lay a sheet to cover everything. However some of the pipes are higher than others.

What should I do about some of these problem areas? Here's some details and possibilities I've gone over in my head:

-Slats are 3/4" thick.

-Distance from the slats to the height of finished floor I'd like is 2 1/2", so 3 1/4" from joists to ideal floor height.

-Tile is about 3/8" thick.

-Huge problem area behind the toilet flange, with a pipe running behind it. It's 2 inches thick sitting on the slat. This leaves me room to basically put the tile on top of it.

-Should I fill this area in with concrete or some type of patching filler?

-Do I need to raise the finished floor height then?

 

Renail existing 3/4 inch subfloor. Then fir up to the bottom of your toilet flange with sleepers. You will have to rip these and nail them right on top of the floor joist below. (leave the 3/4 inch 1x6's) No need for 3 layers of plywood. Remember, allow for the thickness of your underlayment for your tile. Your "underlayment should end up about flush with your toilet flange. Dont worry about unsupported ends of subfloor. Your new 3/4 inch plywood will be nailed to your firring strips and will float out ok. On the ends if its bouncy, then screw these areas. If you can get backing in for more support go ahead, but it will be tough. Looks like you removed a radiator?
Are you putting it back? The height of your floor is all about the toilet flange! If you fir up your plywood should float right over these pipes. Nail plywood only in the firring strips! Dont pop a leak in an old pipe.

Indii

 

Ok that sounds good. Radiator is staying out, it stays pretty warm in the bathroom w/o it.

However, there is still a problem area behind the toilet flange. The pipe is 2 inches thick (well the slipnuts are) leaving only 1/2" left to the bottom of the toilet flange. That's enough to basically have tiles slide in sitting on the pipe and air. No one's going to be walking there but it still seems a bit risky?

In this case, should I raise the flange and my floor height a bit?

You also mention underlayment flush with the toilet flange, but I keep reading the toilet flange is suppose to be flush with the finished floor?

 

Just a couple of questions. Was the concrete on top of these boards? Are they lying on dirt or are the joists lying in dirt? I am thinking it would be best to remove all the wood, replace piping and pour a slab. Wood should not be contacting the ground.

 

There ya go!...

 

Replacing piping isn't an option for me. These are pipes running from my next door neighbor units to main lines, others are going to my downstairs neighbor.

The concrete was on top of the boards. There was nothing lying on dirt, I'm on the second floor.

 

Ok, so the stuff that looks like dirt is concrete and there was a concrete slab over the wood. You need to bring the floor level back up to the original level covering the pipes and coming to the bottom of the toilet flange. It looks like about a 3 inch slab so my concern would be if the joists are enough to support that weight. A load calculation should be done using the depth and length of the joists to see if the would sustain the floor load. Other option is to raise the floor using 2x4's and a new sub floor. Might have to rip the to get the correct height. I think I would run them 90 perpendicular to the joists. The pipes do make this a little tricky. You could also remove the slats and sister larger joists to the existing joists.Hopefully you will get some more opinions from the experts here.

 

Looks like you've got some fun on your hands....Frankly, it seems like there are two options...First, replace all the piping, leave the flange at the height that it is (big expense) or cut the flange and replace it to a new floor height...there are lots of flange inserts out there for cast piping...

So, pull the planks as they look shot anyways, build a new sub floor with 2X4 and 3/4 plywood. Cover this with "Ditra" (http://www.schluter.com/6_1_ditra.aspx) subfloor and tile at will. Install the flange insert to whatever height you need to accomodate the new sub-floor. Just be sure of the length of the flange insert neck before you cut your existing one.

The Ditra costs a bit more but if you pick it up from Home Depot, buy it by the foot...for some reason it is cheaper this way than buying it by the roll, even if you buy the same amount that is in the roll...go figure?

 

Hi eva,

The boards that are remaining look to be in poor condition, many are splintered and cupped. The existing boards appear to be 1", (actual nominal size is 3/4", but these look so old, who knows?) I understand you wish to leave the pipes as they are.

Could you build a layer of flooring to replace those boards with 2x4"s? It would be easy for you to jig the cuts around the pipes. Lay them perpendicular to the floor joists.Lay them close together, glued and screwed, so you have a nearly solid surface. Now, you have raised your floor by 1 and 3/4 inches from the top of the joists.

I'm not certain about the height of your flange, it may have to be raised after the installation of plywood and backer board, but I see some shiny new copper pipe in one of the pictures, so you must have good plumbing skills.

 

Yes, I've decided to rip up the boards, and I'm in the process of it now. I'm going to take this in sections using 2x4s and other varying sizes of lumber. The old boards are indeed 1" (3/4 actual), and are in horrible condition.

In the bathtub area I've layed down some 2x4s perpendicular to the joists as advised by Michael, and some t&g 3/4 plywood perpendicular to the 2x4s. I can't sister large joists as I don't see how I can maneuver them under the pipes/joists.

I plan to go ahead with the ditra, thanks Moth, I'll check out HD once the subfloor is layed.

Connie, from where I am now I'm going to end up with about 4.5 inches from the joists to the top of the finished tile. This actually works out since I'm using an expanding rubber seal toilet flange to go over the existing cast iron. This should also give me enough clearance behind the toilet flange where that big pipe is running. I can't remember the exact size, but perhaps a 3/4 plywood, ditra, and tile in that section. Not ideal but there's no traffic in that section

Doing the copper pipes was the first time for me, as well as my brother. We had to redo a lot of sections that we messed up, good times

I'll keep posting updates, not sure in which sections though, I'm losing track of which sites and subforums I'm posting to. Wish me luck!!

 

Get back with us if you need more help. This is not an easy one but I know you can do it. We would love more pictures of your progress.

 

Mike, I just think your comments are such a nice, personal touch!