Bathroom remodel

KC_Jones

Ok gentlemen, getting outside my comfort zone, but I think that's a good thing for learning.

I am currently doing a gut remodel of one of our bathrooms and I am thinking about doing radiant heat. My current focus is getting the tubes in the floor and since this is DIY my online research seems to indicate limited choices for a subfloor.

My criteria:
1. I want a prefabricated panel that will work under porcelain tiles, including the use of Ditra decoupling membrane above the panels.
2. I would prefer to use 3/8" tubing (~8" spacing?) to keep the thickness down. The bathroom is tiny at 5x8, but the master is right behind it and the plan would be to give it similar treatment when we remodel that room. I have a location adjacent to both bathrooms to put a distribution manifold fed by larger piping. I would think this would make the 3/8" tubing more feasible (I know 3/8" can create head issues).

I think those are the main points for the tubing.

When I'm ready to hook it up it will be run from a heat exchanger off the steam boiler, that will come later when the money allows. Again since it's gutted I'd like to get the tubes in now.

Oh heatloss is about 600 btu's so I am viewing this as floor warming only. The bathroom currently has no heat, but it always has a slight chill compared to rest of house.

I'm sure I missed some points, but that's why I am posting to get some input from those more knowledgeable than I.

Any feedback is appreciated.

STEVEusaPA

5X8, less tub, toilet and vanity plus a bath mat covering a decent amount of the tile floor, isn't much usable space (which you already know).
Why not consider adding either radiant ceilings and/or a panel radiator that's a towel warmer.
Insulating all walls, ceilings and floor and a super insulated window (all stuff you know) will also help.
Any prefab panel will rely on a perfectly flat (not necessarily level) floor so you may have additional build up leveling/flattening the floor.
Maybe gut down to and level the floor joists and use the 1 1/8" warmboard as subfloor w/grooves for tubing, then membrane and tile.

KC_Jones

STEVEusaPA said:

5X8, less tub, toilet and vanity plus a bath mat covering a decent amount of the tile floor, isn't much usable space (which you already know).
Why not consider adding either radiant ceilings and/or a panel radiator that's a towel warmer.
Insulating all walls, ceilings and floor and a super insulated window (all stuff you know) will also help.
Any prefab panel will rely on a perfectly flat (not necessarily level) floor so you may have additional build up leveling/flattening the floor.
Maybe gut down to and level the floor joists and use the 1 1/8" warmboard as subfloor w/grooves for tubing, then membrane and tile.

This is a gut job, everything will be level, plumb, flat, and square when I'm done. Like I said the load is minuscule and I am viewing this mainly as floor warming for the bathroom. Walls may happen in the master as the load is higher in that room, but this room only has 4' of exterior wall that will be insulated with foam and roxul, with all the cracks spray foamed.

Ceilings make me nervous from the freeze standpoint as the attic space is above, yes it's insulated, but this is a leaky 100+ year old house. I don't worry too much about leaks in the unheated attic.

I like the warmboard idea, but will the sell to me? If I go that route I may do my daughters bedroom which is part of the same remodel project. Cost could be a factor there, but the wife likes the idea so....

Alan (California Radiant) Forbes

That's a lot of expense to go to just for floor warming. I'd put in an electric mat.

KC_Jones

Alan (California Radiant) Forbes said:

That's a lot of expense to go to just for floor warming. I'd put in an electric mat.

You are correct and I don't like electric.

JUGHNE

Is the basement open underneath?
We had in wall heat behind the SR. About 6' x 6' of SR wall heated does our 8 x 8 area of shower, whirlpool tub and WC.
This is open to 8 x 12 walk in closet and vanity. That area has 4 x 6 of heated wall. This is on the NW corner of our well insulated house. (1995)
Years later, before closing up the basement ceiling I added extruded plates under the tub/shower area. Limited floor space as you have, the only noticeable difference was warm floor for comfort.

The area with floor heat is 1 1/4" thick layers of plywood with ceramic tile laid directly on the wood. Insulated below. With 100-110 degree water the warm floor is comfortable.
I like the idea of the tubing under the floor on the basement side, simpler. Any leak issue is easy to get to. No laying tubing in wet set of anything.

Manifold in linen closet, there is an extra port as I made provisions for a future towel warmer if wanted, (not needed, just wanted).

KC_Jones

Bathroom is on the second floor, kitchen below. I am not opposed to the walls in addition to the floor, but if i do this the floors will be done.

Mainly trying to figure out the floor detail and what materials are available to me for such a project. I don't have a ton of thickness available ~1.5"-2", but I have a few creative ideas to gain some space if it's absolutely necessary. That involves other rooms and such so need to get the basics figured out first. This is why I was thinking 3/8" tubing.

Thanks for the responses so far.

Gordy

What’s finish floor ceramic tile?

Gordy

If tile. Do 1/2” plywood sleepers 3:8” pex. 1/4” Hardi backer then tile. Build up from sub floor 1 1/4”.

KC_Jones

Gordy said:

If tile. Do 1/2” plywood sleepers 3:8” pex. 1/4” Hardi backer then tile. Build up from sub floor 1 1/4”.

so just a homemade system? I'm good with that, I wasn't thinking in those terms to be honest.

Does the tube get stapled down or do I bevel cut the sleepers to hold it? I can work wood no problem so this shouldn't be a big deal. I would prefer to skip the backer and use ditra, but it sounds like the backer is an integral part of the proposed design?

KC_Jones

Gordy said:

What’s finish floor ceramic tile?

Yes will be tile. Porcelain, but I don't think that detail matters either way.

JUGHNE

There was an old school approach done in 1920's buildings to have floor thickness match adjoining rooms.
Ledger strips 3/4" below top of joists, flooring between the joists so it was flush with the top of the joists.
You would gain some depth and have the opportunity to insulate below heated floor. FWIW

Jon_blaney

Have you looked at Schluter
Bekotec?

Gordy

JUGHNE said:

There was an old school approach done in 1920's buildings to have floor thickness match adjoining rooms.
Ledger strips 3/4" below top of joists, flooring between the joists so it was flush with the top of the joists.
You would gain some depth and have the opportunity to insulate below heated floor. FWIW

Yup, they used it in my old house 50’s more for a mud deck with tile.

Gordy

KC_Jones said:

Gordy said:

If tile. Do 1/2” plywood sleepers 3:8” pex. 1/4” Hardi backer then tile. Build up from sub floor 1 1/4”.

so just a homemade system? I'm good with that, I wasn't thinking in those terms to be honest.

Does the tube get stapled down or do I bevel cut the sleepers to hold it? I can work wood no problem so this shouldn't be a big deal. I would prefer to skip the backer and use ditra, but it sounds like the backer is an integral part of the proposed design?

I’ll see if I can find pics on the computer of my install. All you are doing is filling in between the pex, or in my case I used 3/8 type L soft copper. I’d consider the soft copper for such a small area.

I then filled the grooves with Unmodified thin set when I laid the hardi backer since you thin set the hardi backer, and screw those down.

Ditra is an option. Pricey though.

Gordy

You could also do as jughne suggested, but that involves removing the sub floor. Then just do a mud bed with the tubes, and tile over the mud bed. Which if you don’t have to why?

Gordy

Ditra is fine. The hardi backer did nothing structurally. I just found the ditra more expensive than the Hardi backer.

Gordy

KC_Jones

I have no sub floor T&G hardwood directly on the joists, it's all coming up for complete rebuild. Joists have been hacked for hacked plumbing and they are undersized, especially for tile.

Ditra is more expensive and I have never used it, so it's more of a try it out kind of thing, plus I find cement backer a PITA.

Copper is interesting idea.

I have seen the floor between the joists and it is the creative idea I was thinking about. Need to process this further.

@Gordy would using PEX and filling with thinset be a problem in your eyes? I am guessing leave the loop ends looser for expansion?

Wellness

I guess if you like water; you like water. But @Alan (California Radiant) Forbes had the soundest solution if this is mainly for floor heating and not space heating. And electric way is easier to repair than tubes filled with hot water.

Gordy

I can’t answer as to the compatibility of pex, and thinset. Unmodified doesn’t have the polymers that gives it flexibility like modified. My thinking is it would be fine. Pex in concrete is like peas, and carrots.......


If you are already down to the joists a bud bed could be the way to go. I bed the tubes in the mud bed, and tile on the mud bed.

A very good web site is https://www.johnbridge.com/ It’s the HH of tilers. Might check in to see what a minimum mud bed thickness would be over the joist tops.
They also have a deflecto calculator to see if your floor will meet the requirement for tile.

KC_Jones

Wellness said:

I guess if you like water; you like water. But @Alan (California Radiant) Forbes had the soundest solution if this is mainly for floor heating and not space heating. And electric way is easier to repair than tubes filled with hot water.

How would it be easier? You would have to rip out a tile floor to fix either one. The fix isn't the problem, getting to the fix is.

ChrisJ

Gordy said:

I can’t answer as to the compatibility of pex, and thinset. Unmodified doesn’t have the polymers that gives it flexibility like modified. My thinking is it would be fine. Pex in concrete is like peas, and carrots.......


If you are already down to the joists a bud bed could be the way to go. I bed the tubes in the mud bed, and tile on the mud bed.

A very good web site is https://www.johnbridge.com/ It’s the HH of tilers. Might check in to see what a minimum mud bed thickness would be over the joist tops.
They also have a deflecto calculator to see if your floor will meet the requirement for tile.

I thought you had forced air?

Gordy

Wellness said:

I guess if you like water; you like water. But @Alan (California Radiant) Forbes had the soundest solution if this is mainly for floor heating and not space heating. And electric way is easier to repair than tubes filled with hot water.

KC is running off of his steam boiler to feed the floor. With maybe future expansion? May as well use it as it will be running anyway. I hate our electric rates. 12 cents a KW is what I pay, cheaper than some places, but expensive in my opinion.

You also need room in the main panel for the extra dedicated load. A 120 v system would do it I’m sure, but......

Gordy

Most electric mats are about 15 watts a sf. The benefit is you can run them on a timer, or set them up to come in, and off at certain times when you think the bath will be used, and summer time it can function independent of the heating system.

If 40 sf ran for 8 hours intermittently a day that’s 2.76 a day at .12 a KW. Adds to electric bill in a hurry.

KC_Jones

As said when the master bath gets remodeled I will give it the same treatment, and in that room I need the actual heat not just floor warming. So I don't want to run electric mat all winter long when I have the steam boiler with plenty of extra horsepower.

I would speculate it probably won't even make my gas bill up, just spread the heat around better.

Once the tube details are figured out I will work on the "engine" to drive it. That won't be until at least next year when I free up the money.

KC_Jones

Gordy said:

Wellness said:

I guess if you like water; you like water. But @Alan (California Radiant) Forbes had the soundest solution if this is mainly for floor heating and not space heating. And electric way is easier to repair than tubes filled with hot water.

KC is running off of his steam boiler to feed the floor. With maybe future expansion? May as well use it as it will be running anyway. I hate our electric rates. 12 cents a KW is what I pay, cheaper than some places, but expensive in my opinion.

You also need room in the main panel for the extra dedicated load. A 120 v system would do it I’m sure, but......

Yep, I don't have the room. 1 spare and it has a future plan already. 100 amp service doesn't go far with a small panel.

Steamhead

Keep it simple- keep the steam radiator.

KC_Jones

Steamhead said:

Keep it simple- keep the steam radiator.

There isn't one.

Steamhead

I'd put one in. If the bathroom is small, cast-iron baseboard might work, which would warm the floor a bit more than a radiator.

We know cases where electric mats have stopped working after only a few years. Most times people have us put radiators back in.

And, what @STEVEusaPA said about maybe not having enough floor space for radiant to work well.

Larry Weingarten

Hello, As we’re brainstorming, have you considered radiant walls? The installation could be simpler and have the added benefit of warming around the tub/shower
Yours, Larry

EBEBRATT-Ed

@KC_Jones
Are you really just looking for 600btu?

KC_Jones

EBEBRATT-Ed said:

@KC_Jones
Are you really just looking for 600btu?

And warm toes.

ChrisJ

Be careful.