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LifeProof Vinyl Plank Install using layers of Durock over concrete subfloor vs A-CDX Plywood

I have an odd condition.
I need to raise my 100 sq ft bathroom  up to 1  1/2".
The subfloor is concrete it is an older home with some movement. No cracks visible in the bathroom subfloor.
It is a wet condition that concerns me. 
If I go Durock 
1. Using thinset or mud on the bottom 1/2" Durock layer to concrete subfloor
2. Lay down the next 1/2" Durock layer on top of the 1st Durock with a thinset .
3. Lay down the 3rd layer of 1/2 with thinset. Tape and feather the joints with thinset.
4. Install the Lifeproof Vinyl Plank. Will the Durock crush over time? 

USG was very adamant about not doing it. Because it has not been "approved" as an installation method. They did not know if the Durock would crush.


A. Use a 6 mil Vinyl membrane over the concrete sub-floor.
B. Lay down 3/4" Weather Proof Plywood. Using Redguard to waterproof the top surface,
C. Repeat 2 more 3/4" layers. maybe using an A-CDX rated plywood for the top layer.
D. Fasten with powder actuated fasteners to the concrete thru all 3 layers.
E. Install the Lifeproof Vinyl plank.

I really want this floor to last 15-20 years without having to tear it out and do it again.

Obi-Wan,  your my only hope!
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Posted 2020-09-13T13:12:21+0000  by Cadtek Cadtek
Why not use 1x (3/4” actual thickness) pressure treated lumber as a sleeper instead of multiple layers of plywood?

I’m not sure I’d use powder actuated fasteners because they have a tendency not to seat flush.  I might suggest Tapcons to fasten the sleepers to the concrete and then short deck screws for the plywood to sleepers.
Posted 2020-09-13T13:49:49+0000  by Adam444

Hey there Cadtek,

While I'm all for using a sleeper system for your go between subfloor that Adam mentioned, there is another much easier and simpler product for your situation that's sold online.

It's called DRICORE and it works perfectly for anytime you need to place additional subflooring between your new floor and an existing concrete slab. If you are seriously interested in this system, PLEASE click the link above for more specs and videos regarding this amazing product.

Below are some pics that show it in action, and check out the link above highlighted in orange for further information.

Granted that this option would give you about half of the overall height requirement you'd need to raise your final floor level, it does mean though that you can place additional sheet plywood on top and then the vinyl planks to get to your final height.

Personally, this option would be the simplest version. Afterwards, and as mentioned earlier, you can place more plywood over it, or even tile backerboard as you wanted originally.

As for the Durock/ tile backerboard option directly installed over the slab, the vendor was reticent about installing their product over concrete is that its typically not installed in that fashion.

Concrete (if sealed or has a water impermeable membrane coated over it) is more than good enough for a suitable base for any new flooring subfloor, which is why backerboard installs aren't as common going over it. 

Obviously in your case, you'd want to increase the overall height. I believe with the DRICORE as a base, and then whatever wood/tile backerboard options over that, you'll reach the required 1-1/2" new height you want.

The final reason I love the DRICORE base option so much is that whenever you need to remove the subflooring systems for any reason in the future, it's easier in this method versus any type of screw down or adhesive choices being stuck to the slab.

And lastly, this is a public forum, putting your personal information online for everyone to see (i.e. your telephone number) isn't the best idea.

Hope to hear on your progress soon,


Posted 2020-09-14T19:14:49+0000  by Joseph_HD_ATL
Thanks That is thinking out of the box, for sure. 

The sleeper spacing? 

I had Durock widths at 3', one was 5' long under the vanity, where you could park a chair.  

The rest were 3'x 4' and smaller, at the entry and then in front of the 3x5 shower pan, and wrapping back around to the toilet. 

Think of a plan in a C shape, the 2 smaller legs of the C were entry and toilet. Altogether 90 sq ft.

The other part of this equation is a Zero threshold shower pan which has caused the issue with the height at 1 1/2".
It It was supposed to sit level on the concrete and then all i needed was 3/4 in to raise the floor to the height of the pan.

 Home Depot sells this tub to shower conversion from .f you want to see the picture. you will have to cut and paste the link below into your broswer

The install guide is here also as a pdf.

I could not get the pan height to sit level. I asked one guy to use self leveling when another guy blamed it on the concrete not being level and he came back with mud and left me at 1 1/2". I think it was the drain collar nut under the pan that was impeding it.  I told them both and they blew me off. Maybe I had 2 really bad guys. 
If I knew I could drop it  to the 3/4" I would get another guy. 

I would even cut the concrete. there is a post tensioned cable appearing where the drain was moved . Even then I think we have enough room to cut. If that was $ feasible. I am quoted under a grand to add the height and cut the bottoms of my doors and add a hump under the carpet so I wont stub my toes at 1.5".

I am at my wits end trying to come up with a solution that is feasible.
I don.t get why Durock wont approve the install. It cannot be to crushing  because the stack it on pallets.

Being that the pan is level with the floor and will butt against the plywood . If any movement breaks that silicone seal along the pan where there is no door and wicks into the plywood edge over time that is going to fail. 

It is supposed to look like the vinyl plank continues into the pan . The pan comes already with the plank installed.

Now that you see the bigger picture, any more of your wisdom would be more than appreciated. God Bless you for giving me a little hope. 

I am in Garland Texas. and can provide a number if needed,

The ideal scenario would be get that pan down and deal with a 3/4' height. and then there is the waterproofing.  The bath people said butt it to the plywood and seal,. Or if i was daring cut a section of plank inside the pan and made sure to install a new plank that overlapped the pan edge to cover over the plywood edge.

By the picture link I copied, It is a fixed glass panel and the other half is open, No door.
Posted 2020-09-14T20:42:22+0000  by Cadtek
Thanks Joseph
What does not seem to solve the issue of the water splashing onto the area that is open which will eventually wick into the edges of any plywood product.

 I don't see that Dricore is best in a wet environment from above, where a toilet may leak and then you have 1/2 of water on the floor.

Did I miss something?
Posted 2020-09-14T21:20:32+0000  by Cadtek
You are quite welcome Cadtek,

At least for around the toilet, you can opt for the sleeper slat systems or build up that area via floor leveler or cement for at least 1 square foot (or more) around the flange so that any leaks/damage would be kept at a minimum.

In terms of the water splashing from everyday usage, as long as you install your new vinyl plank flooring properly and run a bead of 100 percent silicone caulk where the edge meets underneath the quarter round or similar moulding, then any water seepage won't really be a problem, provided of course you wipe up and clean any messes as soon as possible.

As easy as the install system sounds for the vinyl planks, I really can't stress enough that enough to ensure the first row and subsequent perimeter of the floor is locked into place via the quarter round. You'd only really need to place the silicone caulking where the shower area meets the floor. 

It's one of those situations where you can go from one option to several on the build, but for what it's worth, DRICORE is a viable option even for your situation.

Posted 2020-09-15T00:43:04+0000  by Joseph_HD_ATL
Here is the main constant threat of water.

The shower pan is already planked and complete, the glass panel is fixed. No sliding or pivot door is used. I have to raise the bathroom floor to meet the height of the zero threshold completed pan. The bathroom vinyl plank will butt against the pan.It is siliconed at the edge. Houses move. Over time that will allow seepage into the seam and plywood will begin to buckle. No wood product will Completely stop a constant source of wet from doing damage over time.

My thought is to go back to Durock. Maybe they didn't approve it was because it is never used over a concrete floor for a vinyl plank floor.

I hope the pictures helped you see the issue clearer. If DriCore is not a wood product my apologies. If you have any other ideas I welcome your attention to my problem and really need some help.

Posted 2020-09-15T03:43:51+0000  by Cadtek
Again, this is one of those situations as I stated earlier where with proper planning, you can choose one or multiple options.

I'll say this one more time....a vinyl plank floor can be waterproof to such an extent as long as it's installed properly and sealed where it meets any shower or wet location areas. As for DRICORE, it is a recommendation, but you can opt for using a sleeper slat system and then raising the floor additionally with plywood and tile backerboard (Durock) as said earlier in this thread. 

As for DRICORE in the shower, that was never a recommendation. In the link I gave you, it gave its limitations on its specs sheets, and it states to never use it inside a shower area. In fact for a shower area, you can opt for building out a mud pan, and then filling it in with bedding mortar to achieve a solid base for your shower area. 

At the end of the day, it's really your call on what you'd like to do. Just ensure all products you use are going to be impervious or dang near to water to ensure no rotting will occur. Water will only seep underneath if it will obviously go there, be it around the toilet or shower. 

Going with a mixture of options as I mentioned before or a basic run of 1" slats with 1/2" tile backerboard over that can and will work. You or whoever is doing the install work, needs to ensure it will be done properly and sealed before the final floor goes over it.

Once that's done, a properly installed plank floor will give you an almost lifetime of durability provided you clean any standing water as soon as possible, that's the final piece of the puzzle for it to work and last.

Posted 2020-09-15T12:58:45+0000  by Joseph_HD_ATL
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