2nd floor bath conversion to laundry room

[jojogaveup]

Darling husband and I are converting the 3rd, unused, bathroom upstairs into a laundry room since I HATE having laundry all over the kitchen all the time because the laundry closet is just off the kitchen. Laundry rooms belong upstairs, where all the laundry is located! Anyway, this is a 6 year old house, with huge I-beam type joists, passed the deflecto by a factor of 3+, the room is 5' x 8'. He gutted the room, added insulation in the floor space for the noise factor, fancy quietrock sheetrock for sound, and insulation in all the interior walls. The plumber/electrician guy revised the electrical, gas and plumbing. We have the Ditra and Kerdi-band and all the right thinsets ready to go. The subfloor is one 5/8 layer under a 3/4 layer - new plywood, glued and screwed. We have a linear drain ready to go in to separate the washer and dryer from the rest of the room and confine and deal with any disasters.

All that said, I found a major deal on Carrera 12" tiles for $3. The question is there is a small, gradual hump in the middle of the floor running across the short dimension, pretty much where the seam is between two pieces of subfloor.

How bad does a hump need to be before we have to do something along the lines of self leveling something rather than just compensating with a bit more thinset? If we do have to do something self leveling about the hump, how thin can it be? What would we use? This hump only affects 1/3 of the length of the 8' dimension, because the linear drain comes into play between the hump and the wall, 3' out from the wall. In other words, wall, 3' space for w/d, 5' linear drain, 5' between drain and door, hump pretty much in the middle of the middle of the space between the door and the drain.

[cx]

Welcome back, Jo.

First thing that caught my eye was your method of evaluating your joist system. Our Deflectometer ain't never heard of an engineered-wood joist, which is what you seem to be describing. It don't know diddly about those and can't help you with your calculations.

On the bright side, it's very uncommon for an engineered wood floor system not to meet at least the minimum code deflection requirement of L/360, which just happens to be the requirement for a ceramic tile installation.

We'll hope your "Carrera 12" tiles" are a name for a ceramic tile and not actually Carrera marble, eh?

As for separating the laundry area from the rest of the structure with a "linear drain," you are taking note that you'll need to have a waterproof barrier of some sort all around that laundry area, including doorways, for that to be effective, yes?

And for the hump in the floor, how bad is it? The industry standard for flatness, considering no tile with any side larger than 15", is no deviation from plane of more than 1/4" in any ten feet and no deviation of more than 1/16th" in any one foot. You reckon your floor meets that?

My opinion; worth price charged.

[Houston Remodeler]

Just out of curiosity,,,,,

Did the plumber add a small water line to feed a small amount fo water to the p trap for the linear drain? Normally such an automatic valve is added onto a vanity sink, toilet or the washing machine. When those are operated, a small amount of water is fed into the trap. That keeps the sewer gasses from coming into the living space.

Y'all have that right?

If you place a 4 foot level over the worst spot on the floor, how many stacked quarters can you slide underneath?

[jojogaveup]

CX

The tiles are marble.

A former project superintendent for the builder, who was the super for our entire neighborhood, is also a friend and no longer has any ax to grind in favor of the builder, assured me the floor is about 3x better than it needs to be regarding deflection. He lives in an identical house right behind me.

The entire room will have a waterproofed floor using Ditra, including up the walls behind the baseboard and the seams.

The linear drain feeds into the former tub drain, as does the washer. I don't think there will be a problem with sewer gases since I do laundry several times per week. I also have another bathroom that is never used and we have never had any sewer gas issues with either of the two sinks or the tub. I think you're picking nits when my only question was about the hump in the floor.

CabotAndRowe

I will use the stacked quarters method tonight and see what I come up with. THANKS

[cx]

Originally Posted by Jo

I think you're picking nits when my only question was about the hump in the floor.

Some of the nits need picking, Jo. We try to give our visitors all the information we think they need for a successful tile installation, including all the peripheral considerations that spring to mind.

Originally Posted by Jo

assured me the floor is about 3x better than it needs to be regarding deflection.

Very, very unlikely that a joist structure would be engineered to a deflection of L/1080 in even the most high-end residential construction. But if you're happy with it, I'm happy with it.

Did you tell your friend that you intended to use natural stone tiles? Did he then indicate that the joist structure was adequate (requiring it to be twice as rigid as for ceramic tile) but that you'd need to have a double-layer plywood or OSB subfloor before you install your tiling substrate and tile? These are technical considerations required by industry standards and shouldn't be guessed at. Really.

Think I responded to your question about the hump in the floor in post #2.

My opinion; worth price charged.

[RaymondJ]

Why not be sure about the floor structure being L/720 or better (required for stone)? A little research beats the heck out of a failed installation

[jojogaveup]

Never mind.

[Duggie]

Hi Jo.

Just wondering if you have your linear drain installed yet? If you do, can you post a couple of pix? I am about to embark on redoing my laundry room, and I like this idea for my situation.