What type of underlayment is this? (tiling, subfloor, vinyl, countertop)

[home n00b]

Hello,

I am in the demo phase of renovating our powder room (1/2 bath). The previous owners had installed carpet in the room (yuck, as it had a urine stench), and now I am working towards prepping the floor for tile.

Prior to beginning the project, I had figured the carpet pad would have been stapled into the plywood subfloor, like the rest of the house; but, I was wrong as I found that adhesive/glue was used instead of staples.

Additionally, underneath the adhesive material, there is a gray, paper-like layer (adhered to the top of the plywood). At first, I thought it may have been vinyl tiling that the previous owners had carpetted on top of, but after trying to peel some of it, it tears like construction paper. I assume that it is a moisture barrier to prevent water from soaking through the carpet pad onto the plywood, but again, I'm not sure.



If anyone can provide any thoughts as to what the material may be, I would appreciate it, as at this point I am unsure of how to proceed:

• Can I use a leveling compound directly on top of it, and then tile?
• Or, do I need to strip it off and get to the plywood?

Also, I'm not very familiar with using glue to hold down carpet pad, but is it typical for grooves to be embedded after removing carpet?


The house was built in 1989, in which I believe the carpet/pad may be original to the house. I've attached pictures to help depict my poor description above:

1. Floor_001.jpg shows an area where I had scraped off some of the glue to reveal the gray material that is in question.
2. Floor_002.jpg is picture of basically how the whole floor looks.
3. Floor_003.jpg is a section of the toilet footprint, in which the plywood and glue boundaries can be seen. There is a 2 x 2 area where the toilet sat, in which there is no gray material, but rather just plywood and/or glue.

If you need any other information in order to help make an assessment, please let me know! Thanks in advance for any help or advice you can provide!

[faithfulFrank]

I could not really tell, but the 3rd picture looks like it is clearly an OSB product.
The problem is that there are diferent types of OSB.
The most common is 7/16" thick..(like aspenite) Some I've seen is 1/4 inch, but they also make stronger stuff that is 3/4" T & G called advantech.

If you pulled the toilet off, can you see where the toilet flange is to see how think it is?

I guess the question is, has the smell left now that the carpet is gone? Is the subfloor you see in good condition? What do you ultimately want to end up with?

If the smell is gone and the floor is in good condition, perhaps you do not need to remove it. you MAY just be able to seal it and go over it with cement board and tile, or whatever you want to do. Depending on the condition and thickness, it may just be better to remove it. How is it attached?is it indeed just an underlayment, or is it the subfloor?

Frank

[Omaha Rocks]

I can't really tell by looking at the pictures. But here are a few thoughts...

First, the "grooved" look you're seeing is simply due to them having spread the carpet adhesive with a notched trowel. It's typical.

That said, I'm going to assume that the OSB is the sub-floor. I have no idea the thickness. On top of that is likely a sub-floor, and there's no way of knowing exactly what it is, because there are so many different kinds. Like Frank said, it's apt to be 1/4 inch to 7/16 inch thick. The gray stuff is probably a moisture barrier, much like tar paper.


If it was my project, I'd remove the under-layment & get it down to the sub-floor. If you're going to lay ceramic/stone tile, install 1/2 inch cement board. Apply Thinset adhesive, and install your tiles. Then grout & seal.

[Synergy1]

I agree with Omaha. Remove all till you see sub flooring but I would go to the joists then new all the way up. That way you know the stuff will be gone even if you seen the joists damaged or the insulation (if any) would be saturated and need removal. Wear gloves please.

[home n00b]

Thanks guys!

I believe the OSB is 7/16" thick. The urine smell left when I removed the carpet and pad; I'm guessing the moisture barrier helped prevent it from getting to the OSB.

I'm going to research a bit, but plan on stripping the floor down to the sub-floor, and then using cement backerboard. I had used cement backerboard on a bathroom countertop, and it worked great.

However, in trying to assess all possible options, would it even be feasible to use the existing underlayment to tile on, given the adhesive that is currently grooved across it?

[Omaha Rocks]

Originally Posted by home n00b

Thanks guys!

I believe the OSB is 7/16" thick. The urine smell left when I removed the carpet and pad; I'm guessing the moisture barrier helped prevent it from getting to the OSB.

I'm going to research a bit, but plan on stripping the floor down to the sub-floor, and then using cement backerboard. I had used cement backerboard on a bathroom countertop, and it worked great.

However, in trying to assess all possible options, would it even be feasible to use the existing underlayment to tile on, given the adhesive that is currently grooved across it?

I'd advise against it. The point of the cement board is to provide a surface that doesn't flex. You can't get that from typical underlayment.

[faithfulFrank]

Everything said so far was spot on. Sorry for my typos on my last post.
I too would go down at least to the subfloor....perhaps even to the studs.

The determining factor is the height of the adjacent floor. If you intend to put down 1/2 inch cement board for tile, know that the proper way is to put mortar down both before and after the cement board, screwing it down, taping seams, then laying the tile. When all done that can easily be over an inch thick, perhaps more. That fact itself may necessitate going down to the subfloor or to the joists. The benefit of going down that far would be to be able to check the plumbing, run electric, etc.......

Frank