Should I glue thinset down cement board hardibacker to my plywood subfloor or just use screws when remodeling an upstairs bathroom?
Asked by Victoria Marchand 
4 weeks ago
Last Updated: August 22, 2024
I’m in the middle of renovating my upstairs bathroom and I’m a bit confused about whether I should glue down the cement board to the plywood subfloor or just use screws. Any thoughts on this would be super helpful. Thanks a bunch!
I work on tiling bathrooms for a living. My go-to method is always using thinset and screws to secure it in place.
Definitely
I feel the same ))) Been in the tile industry for over 20 years
If you are using 1/4” thinset and fasten. If you are using 1/2” screw down as recommended by the manufacturer
Hey, you should really listen to the tile guy below. I’m just a builder who might not know everything 😂
Both. And secure into the joists. Seam tape is crucial as well. Creates a continuous surface
One way to properly install over a plywood subfloor is to utilize an uncoupling membrane instead of just backerboard on the plywood.
Hey , that orange Schluter stuff you’re referring to is the uncoupling membrane, right?
Nearly all tile materials companies have their own uncoupling membrane. I personally use Ardex Flexbone, but Schluter also offers one. However, most of their products are orange. If you decide to go with them, you would use the Ditra system.
The product is called Ditra. It needs to be cemented down to your subfloor, so make sure the subfloor is securely screwed down and in good condition.
Cement board is effective. I’ve used it for years without any problems, as has my grandfather who has been tiling for as long as I can remember.
Methods and materials improve over time. There are more reliable ways of doing things now to prevent future failures. The argument of “I’ve always done it this way” doesn’t hold up when looking at long-term results.
Try mixing the thinset a bit thinner to make laying the Ditra easier.
You got it, !
I learned the hard way from many jobs ago.
Is any better now that it’s new? It’s hard to predict how it will hold up in 10 or 20 years. But in reality, the tile job will probably outlast the current style. It’s more likely that it will be replaced because of changing trends rather than actual damage.
Materials nowadays are superior to how they used to be, and the way things were done 20 years ago is not how it’s done today.
Yeah I pretty much agree. But the old school way lasted over 20 years in most cases. However, they will likely get replaced before that, so new and updated methods may not make much of a difference.
I went through the Hardi Backer manual and it recommended applying a thin coat of thinset on the floor before placing the Hardi Backer and securing it with screws… that’s how I remember doing it. Hardi Backer provides clear instructions… check them out to see what they suggest.
The solution to this is pretty simple… if you want the company to support their product, make sure to follow their installation instructions precisely
Oh, just to confirm, since you’re thinking of using this on top of a current floor structure, I’m assuming you’ve already checked that your deck meets all of their structural requirements, including maximum deflection.
Attach board onto bed of unaltered thinset and use tape to cover and smooth out all the joints with modified thinset
Forget about cement board and opt for an uncoupling membrane instead – just follow the manufacturer’s instructions.
Both
First apply mortar, then proceed to screw.
In my friend’s 1950s home, cement board was installed in the main living spaces without thinset. As a result, the grout is showing signs of cracking in numerous areas. Interestingly, I opted not to use thinset in my own bathrooms that I renovated 18 years ago, and I haven’t experienced any cracking. I currently prefer using Schluter Ditra as it is far more convenient.
Right now is the perfect opportunity to ensure that the floor is even, smooth, and level.
I have experience with a flex bond product in similar constructions, but without being present physically, I cannot give specific recommendations without risking malpractice.
Consider using Ditra instead.
When working with cement board or hardi, make sure to apply thinset underneath using a 1/4 square notch trowel and secure it with special cement board screws.
You have options – you can go with either method. Personally, I went with thinset and it turned out great. And of course, I made sure to use screws too.
Hey there! I’m the flooring guy. Just so you know, it’s best to use both thinset and screws. That’s the right way to do it.
I have consistently relied on exterior Liquid Nail for this purpose.
According to the experts, thinset and screws are the way to go.
There are no personal opinions involved in this matter. Only facts are considered. Glue is not recommended. It is recommended to use thinset and screws according to the guidelines provided by the manufacturers. There are no alternative methods.
You should consider using Ditra for that.