Do I tear up plywood?


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Old 06-04-14, 04:53 PM
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Do I tear up plywood?

Hey guys, I just ripped up vinyl glue down type "tile" from my bathroom upstairs. I then noticed they nailed down and possibly glued a piece of 1/4" plywood over the subfloor. I want to lay down porcelein tile but I was wondering if I need to remove the extra 1/4" piece of plywood to get down to my original subfloor? I've included a picture you can see what I am talking about. I just worry that if i don't remove it and then lay down cement board, then tile it will be raised much higher than the carpet where they would meet causing a toe stubbing nightmare! Thanks guys, any advice helps!

 
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Old 06-04-14, 05:04 PM
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Kind of looks like luan... if so I would definitely remove it. Maybe pull up your toilet and cut out a small piece that will be hidden and see how easy it comes up. Underlayment shouldn't be glued down but you never know. Maybe look and see if it goes under the tub.
 
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Old 06-04-14, 05:08 PM
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i googled Luan... to me it does look like that! it's really thin I know that.. Once I do get it removed, i would then lay down cement backer board over my subfloor, then I can tile over that like I have done on my concrete downstairs?
 
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Old 06-04-14, 07:09 PM
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If you don't want to take off the luan and still put on the backer board you can get transition pieces to make up the difference in height. But yes it will be a bit on the high side.
 
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Old 06-04-14, 08:48 PM
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Originally Posted by norm201
If you don't want to take off the luan and still put on the backer board .............
Sorry Norm but that's against all recommendations from those of us that write tile installation specs and strive to do things right. The luan & other 1/4" ply does virtually nothing to stiffen the floor. The luan should be removed and the subfloor preped before installing the tile backer into fresh thinset etc.

JSB, please tell us what the subfloor is made of including not only the plywood but the framing. Type & size of the joists, their species and grade if possible, their spacing and the unsupported span. Measure accurately. Include the age of the house and where it's located.

Jaz
 
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Old 06-04-14, 09:10 PM
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Jazman, I am guessing I will need to pull up the luan wood so I can show you pictures of the subfloor. I don't know how I am supposed to tell you the size of the joists and stuff? The house is in San Antonio, TX and built in 2003.
 
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Old 06-04-14, 09:25 PM
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What I was trying to do is determine if the subfloor system meets minimum specs for deflection. The max recommended deflection for ceramic tile is L360, which is also the min. spec for modern homes for rooms other than sleeping rooms. So, I'm betting your floor is at least L360.

You don't have to see the joists to measure them. Drill a small hole in the floor and stick a stiff wire or dowel until it touches the ceiling below. Then take a nail and insert head in hole and hook the subfloor, measure and do the math.

Jaz
 
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Old 06-05-14, 04:51 AM
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Sorry Norm but that's against all recommendations from those of us that write tile installation specs and strive to do things right. The luan & other 1/4" ply does virtually nothing to stiffen the floor. The luan should be removed and the subfloor preped before installing the tile backer into fresh thinset etc.
Yes, you're correct. I should've realized before responding. I've done this in the past and have been lucky and have had no problems. But then again it was in a very low traffic area. On the other hand I did an area where an entrance door was being used constantly and even with cement board on the plywood floor the tile eventually cracked. The door needed to be properly installed and secured.
 
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Old 06-09-14, 07:02 PM
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OK fellas, been working on the bathroom whenever I get a chance been super busy! The entire bathroom is gutted and the luan floor is gone.. no glue under it but a million long ass staples! I am in the process of removing all the staples, I've include a picture of the room, and also a closeup of the subfloor so hopefully you can tell me if it's OK... to me it kinda looks like OSB wood. hopefully ya'll can tell. It also looks to me a little like where there is a couple seems it seems the seem is "sticking up" a little. Once cement board is installed is there a little play in it to take out minor uneveness?



 
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Old 06-09-14, 08:16 PM
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All right, looks like you're not too concerned if the framing is stiff enough for tiles. If you are, get back with the joists' info, spacing and exact span. Best to make sure.

The pics of the subfloor are confusing to my eyes. One looks like ply, the other looks like OSB. Are those paint drops on the floor?

Any peaked seams need to be sanded to within 1/32" of the adjoining sheet. Re screw the subfloor as necessary. Be sure to spread thinset under the concrete backer and fasten & tape per directions.

Jaz
 
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Old 06-10-14, 05:52 AM
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You look like you are down to a single layer of flooring as I can see the standard gap at the walls and the fact that the tub is also sitting on this layer. Therefore, very important to follow up on Jaz's questions about the makeup of the joists, spacing and spans. Not sure the age of the house, but, if the OSB saw a lot of moisture during the build prior to the roof being enclosed, the swelling that you noted may be a bigger issue than just sanding. I've seen it pretty bad where we had to replace everything, hopefully you can provide us some encouraging info.
 
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Old 06-10-14, 07:05 AM
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Jaz, I am concerned with anything and everything! I was re reading your post and I was confused on what exactly youre telling me to do to find out the info you want. The house is built in 2003. The white stuff on the floor appears to me to be drywall texture or mud. In some spots it is pretty flakey and dry/dusty. Please try and help me understand better what it is I need to do to tell you joist size, spacing etc. Thanks guys! I want my tile job to last so Id like to do it right! This is what a seam looks like
 
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Old 06-11-14, 10:42 AM
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If you simply measure the space between the ceiling below and the plywood on the second floor, you will know the size of the joists you have. So, the answer might be 9.25" to the bottom of the ply. This would tell you the joists are 2x10's. Their spacing is obvious cuz you can now see the fasteners, hopefully it's every 16". The span will be more difficult, but you can get close. Once again, since the house was built in 2003 and was inspected etc. this number is less important.

From the pic I can see the seam is peaked and then the floor does downhill. You need to fix this. You may want to run a circular saw blade in that seam, (if there's a joist under there), then a belt sander. The area to the right seems to dive about 3/16" in 6-8". That's way too much. Self leveling or a portland based patch is in order.

Jaz
 
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Old 06-11-14, 10:46 AM
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Looks like OSB, and not in the best of shape. Also looks like it could be square edge and not t&g. At a minimum, you need to check to see if your floor is stiff enough for ceramic tile. You need to find out the size of your joists (ex 2x8’s) the on center spacing (usually 16”, but could be 19.2, 24 or something else) and you need the unsupported span. You can easily get the oc spacing by measuring the distance between the nails securing the subfloor. If you drill a small hole in the subfloor you can use a cut piece of a hanger or something else to stick in the hole. Make a mark on the hanger when it hits the ceiling below, then take it out and measure from tip to mark. Subtract off the subfloor thickness. That’ll give you your joist size. If the measure is 7 ¼, you have 2x8’s, if its 9 ¼ you have 2x10’s. To get the unsupported span you need to measure the span from below, from support to support. To get the thickness of the subfloor, use a nail, and stick it in the hole head first, pull it up to the underside of the subfloor, mark it and then remove it and measure. Once you have these numbers, report back here with them.

If the framing is adequate for ceramic and the osb subfloor is at least 5/8” you can probably move forward from there. You’ll need to make sure that the subfloor is properly fastened to the joist, and adding many many screws should do that. Sand the seams per Jaz instructions above. I’d add a minimum 3/8” exterior glue plywood over the osb as the next step. If you can go with thicker plywood, that would be better. Reason being the osb doesn’t appear to be in good shape and looks like square edge, not t&g. The plywood underlayment gets screwed to the subfloor only. It gets laid perpendicular to the floor joists. The screw pattern should be every 6” in the field and every 4” around the edges. Jaz will probably tell you to use more screws. Make sure the plywood seams don’t line up over the osb seams. After that, use ditra instead of cement board. Go to Schluter’s website for instructions on how to install ditra.

I see Jaz beat me to it.
 
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Old 06-11-14, 01:26 PM
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so once I get the OSB prepared I have to add plywood ontop of that, then ditra ontop of that, then tile? Won't that make my floor vastly higher than the carpet leading into it? seems like a lot of material buildup so I just wanted to double check. I will get those measurements tonight!
 
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Old 06-11-14, 03:26 PM
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Let's wait about whether to install more underlayment for now. You haven't told us how thick this OSB is yet, and as Mike noted check to make sure it's t&g too. Take a good look at the subfloor and make sure it's not damaged anywhere. Report on the subfloor and framing.

Your alarm that the new floor will be higher than the carpet side, is no reason to not do the floor right. In the old days you'd have about an inch of mortar under the tiles cuz there was no concrete board or Ditra available. Bath floors were always a good 1" or more higher, people lived and their toes are just fine.

You want all the floors to be the same level..........install the same type of flooring in every room like most of the rest of the world. Tile everywhere!

Jaz
 
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Old 06-11-14, 04:35 PM
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lol tile everywhere is boring! I like to have hardwoods downstairs, carpet up for bedrooms, and tile bathrooms just to make it hard haha... But I drilled a hole through the floor and stuck a dowel in and it went in just a hair short of 16" so about 15 3/4 or so.... and doing the nail trick it shows my subfloor as being 3/4" thick! I have no idea what t&g is? is that tounge and groove, and if so how do I tell?
 
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Old 06-11-14, 07:03 PM
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Sixteen inches huh, must be flat trusses like the one below.

You think the subfloor is 3/4". And yes t&g is tongue & groove. How do you tell if it's t&g? How about the spacing, and span? Let us know when you figure it out.

Jaz
 
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Last edited by JazMan; 06-11-14 at 07:29 PM.
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Old 06-16-14, 10:21 PM
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the subfloor is for sure 3/4" i measured with the nail. And for sure 16" as measured by sticking a dowel in and hitting the first floor roof. It's hard to see the nails towards the middle of the room, but it appears to me they are 24" apart. Hopefully that's the info you are looking for
 
 

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