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-   -   Bathroom Remodel - Down to the studs and joists (https://www.johnbridge.com/vbulletin/showthread.php?t=129586)

HouseOfJoe 08-02-2020 01:59 PM

Bathroom Remodel - Down to the studs and joists
Hello all,

I joined this site...just checked...15 years ago! Wow, time flies. Never posted much, just lurking in all the threads usually answered any questions I had. This is just a fantastic community, you guys are so generous with your time and knowledge. You guys are a tremendous resource for people like me. So thank you!!!

So I've bought and remodeled two houses over the years, and now I'm on my third. Have done most of the house over the last four years and now I'm down to the biggest (and most expensive!) project, the main bath.

It's not big, about 8.5 x 7. The guest bedroom beside it has (had) a large closet, I've stolen a 3 x 5 foot section of that, so the total will be about 75 sq ft. I've removed the cast iron tub and the stolen closet space will become the shower (no tub going back in). The plan is to go Schulter all the way (except the curb, I'll build that and cover with Kerdi). I've never used the Schulter system before but you all seem to think highly of it and all the youtubers seem to like it too, so other than the painful impact on the wallet, I'm excited to work with it.

The demo is about 95% done. When they did the tile floor they put plywood *in between* the joists (level with the top of the joists), put deck mud on that then tile on top. Looks like it held up for 60 years with nary a problem. I was dreading the process of breaking it out, but once the tub was gone I could get a crowbar under one side and it all came out in 20 minutes!

Sorry for the long post, but I'm expecting I'll need to ask a question or two as I go along, so I wanted to give as full a background as seemed reasonable. I know CX likes that!

So my only question at this point is the floor height. The finished tile will be going up against a hallway with red oak floors. Right now from the top of the bathroom joist to the finished surface of the hallway red oak is 1.5 inches. 3/4 of that will be the ply subfloor (or 23/32 I suppose). 1/8 will be the Ditra plus a whisker for the modified thinset. So ballpark I've got 5/8 to go. The tile is picked but not bought, so I can't verify the height right now, but it's a 12x24 porcelain tile that did not look unusually thick or thin to my eye. Assuming 3/8 or so for the tile and thinset, that leaves me a quarter inch low. (btw, deflecto with my 2x10 joists comes back with L/687).

Making the assumption that my numbers above are correct, what's the best way to make up that difference? I don't think they even sell true 1 inch ply, do they? Do I just slap a 1/4 inch layer below or above the 3/4? If that's the suggestion, do I sandwich it with thinset? And I would want the seams of the two layers to be perpendicular to each other, or at least not exactly aligned, yes? Or is there another, better solution than using an extra 1/4 ply? And whether the 1/4 inch solution is used or not, what grade is most desired for a subfloor?

Thanks in advance! Let me know if anyone has any questions that I haven't already answered.


ss3964spd 08-02-2020 02:18 PM

Welcome back, Joe, it's about time. :D

If you need to add 1/4 ish of an inch consider using Ditra XL instead of regular Ditra. XL is 5/16" thick. And if you really want to make Mrs. Joe happy, use Ditra Heat Duo (also 5/16" thick) and have a warm tile floor too. Or, if the extra 1/16th is too much regular Ditra Heat is 1/4".

Don't even try to use 1/4" ply. Instead, you could gain the 1/4" with a tile backer board over the ply and then one of the Ditra products over that.

HouseOfJoe 08-02-2020 04:53 PM

Thanks, Dan, I’ll check out those other Ditra options. Mrs Joe would LOVE the floors to be heated, and now that you’ve given me a practical reason why it would make my life easier I’ll give it some thought, but my budget is already hemorrhaging! So we’ll see.

HouseOfJoe 08-04-2020 12:12 PM

So thanks to the Ditra Heat being virtually the exact height I need to match floor levels, and because my better half had been pushing for heated floors all along, looks like we'll have a heated floor!

So now the question is, do I heat just the floor and not the shower, or do I do both? Square footage of the floor is about 55 or so, the shower is about 15 additional. I had at first simply assumed that no I wouldn't do the shower, but the cost difference is minimal. Since there's not much difference in cost, maybe I should just do it all?

I'd appreciate opinions on the pros and cons of including the shower in the heated floor.


ss3964spd 08-05-2020 07:21 AM

I considered heating the floor of my curbless shower, Joe, but opted out and only heated the main floor, about 60-70 Sq/Ft I think. My rational was that of the total time spent in the bathroom, that which is spent in the shower is relatively short, and while actually in the shower one is standing on a tile floor being warmed by hot-ish water. It's only the one or two steps in and out of the shower where your and Mrs. Joe's feets would experience a brief chill.

After living with it it was the right choice for me. Haven't ever wished I'd done the shower floor.


jadnashua 08-05-2020 08:54 AM

If nothing else, heating the shower floor will dry things out quicker. Normally, that's not a big issue. It obviously does take more materials and costs more. Whether that's worth it to you, can't say! I put in a heated towel bar in my master bath...wasn't needed, but it's nice. Cost more than it would have to heat the floor, but I have hydronic heating in the floor there, anyways!

ss3964spd 08-05-2020 09:45 AM


Originally Posted by Jim
I put in a heated towel bar in my master bath...wasn't needed, but it's nice.

One of the many benefits of doing it yourself and thereby saving a bunch of money on labor costs is having the leeway of justifying some upgrades you might not be able to consider otherwise.

I took that leeway to heart. :D

HouseOfJoe 08-05-2020 03:43 PM

That was my initial take too, Dan. Why bother when the hot water is going to heat it up? But on the flip side it's such a small additional space. But then on the OTHER hand, if I do it, then I have to mud, then Ditra, then Kerdi the shower floor, right? And get the wire through the curb in a waterproof fashion?

Probably just not worth the fuss. Although Jim makes a good point that it ought to help dry the shower out faster, which certainly couldn't hurt.

And I've already got a heated towel rack bought. Don't care about warm towels getting out of the shower, I care about dry ones getting IN!

jadnashua 08-05-2020 06:45 PM

Drying the towel out after showering keeps them from growing nasty stuff and smelling for days, so while a warm one is nice, it also saves on laundry!

There are some videos showing how to get the heating cable through, or rather over a curb on Schluter's website. It's easier if you're using their foam curb, but can be done other ways, too.

ss3964spd 08-06-2020 05:50 AM

Will definitely help dry the floor faster, at least during the months it is in use. My shower floor dries pretty fast, especially in the areas where the warm water warmed up the tile, but I also squeegee mine like a mad man, including the floor. I skirt the towel issue by having two, and just alternate.

But like a heated floor, heated towels are a sublime luxury.

HouseOfJoe 08-06-2020 01:06 PM

So when I put in the subfloor, do I want tongue and groove plywood, or just regular? I'm not sure of the merits of the two approaches. Opinions, anybody?

Also, what's the desired grade?


jadnashua 08-06-2020 02:22 PM

The FIRST layer of subflooring needs to be T&G, or have all of the long seams blocked so they are supported. Second layers do not need that. There's an article in the 'libbery' (sic) that describes how to install it. Basically, you do not want any of the seams to line up between the two layers, but there's a bit more to it.

HouseOfJoe 08-10-2020 05:27 PM

Anyone have any opinions on the Schluter shower pan vs mud and a Kerdi membrane? I was just assuming I was going to do mud, but for whatever reason the Schluter pan caught my eye today.

Same for the curb. It seems like a no brainer to just build it out of 2x and kerdi it, but are there any advantages to using the Schluter curb?


Carbidetooth 08-10-2020 05:52 PM

The only benefit I can see to use foam pan is speed.

On the flip side:

If I'm not mistaken slope is around 1/8" per ft.

Must be installed perfectly level

Relatively expensive

Frail by comparison

Small mosaics questionable as to stability

Space made to fit pan rather than the other way around

I'm sure there are more. If you're prepared to make your own, I'd surely recommend that. I like steeper slope. I don't think 5/16" or even 3/8" per ft. is too much. More for pebbles (better yet no pebbles). Death to birdbaths.

Fast draining showers make me happier...whoosh!

cx 08-10-2020 06:27 PM


Originally Posted by Joe
It seems like a no brainer to just build it out of 2x and kerdi it...

Not quite, Joe. Build it out of 2x, cover it with drywall or CBU and Kerdi it, yes.

What Peter said about the foam trays, but the only time speed would even be an advantage is if the shower were already prepared in the exact size, shape, drain location and level, which is rarely the case in a residential application.

My opinion; worth price charged.

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