I am having a full basement bathroom installed and just wanted to ask a few questions regarding tile installation.
Half of the basement is already finished. So, we will be breaking through the wall that separates the finished from the unfinished side and adding a bathroom there.

My friend is a contractor who is doing the work, including tiling (except electrical and plumbing).

Here is his plan he gave me for the tile installation.
He said he and his guys are good a the tile work and he even offered to show me jobs he has completed....

Floor:
2x4 sleepers to get the bathroom level with current finished area
Plywood subfloor (3/4" tongue and groove underlayment)
Plywood screwed down (apparently he said they use a lot of screws to secure the plywood)
Thinset and Ceramic Tile over plywood floor

Shower:
Swanstone shower base (bulit up on same sleepers and plywood as rest of bathroom floor)
Quikcrete Sand topping mix under Swanstone base for support
Durarock walls
Thinset
Ceramic Tile
NOTE: 2 of the 3 shower walls will be exposed on the backside. The third wall will be the inside wall of an adjoining closet.
Question: What should I use for a vapor barrier? Plastic sheeting behind the Durock or a roll-on membrane applied to Durock?

I have read that tiling over 2x4 sleepers on concrete is a bad idea.....
Apparently, moisture/dampness in the voids created by the sleepers can cause movement in the 2x4 sleepers...thereby possibly causing cracked tiles/grout. True? Any remedies for this?

Overall, does the plan look good? Any criticisms or suggestions would be helpful.....

If more info is needed, please let me know and I wil provide.

Thanks.
mm

Moisture may come up from the slab to eventually effect the wood over top (sleepers and plywood).
Installing tile direct to the plywood is ridiculous especially in a basement where moisture content is usually higher.

The best way to create an even plane for tile is to build a mortar bed and install tile over top. A mud bed allows you to adjust the high while maintaining a level and flat surface. Cheap materials but hard work.


Liguid (roll-on) or solid membrane applied to durock is best.

Does this mean that the rest of the basement floor has been framed in the manner you described for the bathroom? If so, you my be asking for trouble down the road if there is the slightest bit of moisture under that floor.

All lumber that comes in contact with concrete below grade must be protected by a moisture barrier. And pressure treated lumber is not approved for interior use.

Yup.....the current finished basement (as far as I can tell) is built up on sleepers and plywood of some sort. The floor is definitely not directly on the concrete. We have carpet on top of the subfloor.
That is the way it was when we bought the house....
It was approved and permitted by the town too.....
Not that that means anything though, I guess...

Luckily , we have never had water on the finished side of the basement (as far as I can tell). I do not see any signs of water infiltration...no odor, no wet sheetrock.
I do run dehumidifiers in the summer regularly and I have humidistats in most of the rooms in the house to keep an eye on humidity.
I also have a pellet stove in the basement and it runs almost all the time, keeping the basement rather dry.

mm

Don't know what area of the world your from but in my area thats code.

The subflooring isn't in contact but the 2x4 lumber is. How can you be so sure there are no problems when you can't see under the floor.

You may dodge a bullet on the original floor but you won't be so lucky in the bathroom where the potential damage from water and moisture is 100% greater.

As Harry suggested,you would be better off with a mud bed underlayment system for the bathroom.

It's up to you how much risk your willing to take on the recommendations of your contractor friend.

Is there a permit for the bath reno?

I am in Connecticut, USA.

Why would the town approve and permit something (like a basement subfloor built on sleepers) if there is potential for failure?

Unfortunately, your're right, I can't tell with absolute certainty if there is any problems, just going by my nose and eyes.
Yes, there is a permit for the bathroom addition.

Wouldn't the combo of tapcon screws and PL construction glue be strong enough to hold the 2x4 sleepers in place, thereby minimizing movement?

I will try to look into the mudjob, but I will have to try to find a reputable guy in my area, plus I bet it's real expensive due to the labor involved....

thanks again.
mm

Each part of the country and municipalities have their own code rules.

Where the wheels fall off the cart is in the various inspection stages. For example in your job, inspection stages may be something in this order:
1- rough-in plumbing
2- framing (if structural)?
3- insulation / vapor barriers ?
4- final inspection for occupancy usage

Where the wheels fall off is there is no inspection for the floor system. Nothing is looked at by an inspector until after all the tile is in place and the room is finished. What they wont see is how that subfloor /underlayment section has been constructed. This is how failures happen.

This may or may not be the case where you live and you may be lucky that nothing will happen as per your contractors plan.

Wood,water and poor construction methods don't mix and if you can afford to do the job twice, carry on.

I'm certainly not going to tell you that your current plan is what I would approve. That is my professional opinion.

I just talked to my plumber...He's gonna put me in contact with a couple of tile guys.

But what about something instead of tile?
I'd rather not do a vinyl/linoleum floor.....but what about an engineered hardwood floor? Or laminate?
Would they work?

thanks again for your help......really appreciated.

mike

If you went with a wood or laminate floor, it would have to be a floating floor so you could have a vapor retarder underneath. As long as you keep the humidity fairly consistent you shouldn't have a problem.

Once you start to look at alternative materials that are not moisture friendly, the question I would ask is, does this bathroom tub/shower get used once a day? If so then tile or vinyl is the only choice.

I have yet to see a laminate floor that could be used for a bathroom. The product is prone to buckling and delaminating in high moisture areas, especially basements. In most cases its a problem caused by improper installation. 99% of the laminates are made with MDF backings which fall apart once exposed to water.
Engineered hardwood is ok for the general basement areas but it would not be a good choice for a bathroom.