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-   -   OSB to durock install (http://www.diychatroom.com/f5/osb-durock-install-30525/)

acfrqflyer 10-23-2008 08:29 PM

OSB to durock install
 
hi there,

I'm re-doing my bathroom floor which has a 23/32" OSB sub-floor 16" o.c. I had to cut some pieces out of the floor due to rot and replaced it with new OSB. The sub-floor now has a few seams. Now their is a mix of new exterior grade osb and old OSB (i thinks its interior grade). I brought 1/2" DUROCK and planning to place ceramic tile on top of the durock. My question is : the mortar bed that goes in between the OSB and DUROCK should be what type of thinset? (unmodififed or modified?) Also, do I have treat(seal) or protect the OSB before applying the thinset??? The room is only 35 sq. feet..

Thanks for the info...

Bud Cline 10-23-2008 08:38 PM

Use unmodified thinset, do not treat the OSB:) with anything.

Termite 10-23-2008 09:17 PM

Also be sure to "mud" and tape the seams of the durock with thinset and mesh backerboard tape.

acfrqflyer 10-23-2008 10:31 PM

when tapeing the seams of the durock do i also you the unmodified thinset??

I appreiate the info. thanks

RippySkippy 10-24-2008 07:33 AM

Mud the tape when you set the tile, what ever you use on the tile will work fine. By doing it at the same time, you'll lessen the chance of creating a bump at each seam.

acfrqflyer 10-24-2008 08:09 AM

thanks everyone for the info. hopefully, everything works out.

JazMan 10-24-2008 10:41 AM

First of all, .....because words mean things, thin set mortar should not be referred to as "mud", especially on a tile forum. You do NOT mud the seams and tape them. Mud is sand/cement and is applied an inch thick or so as the base for tile. Thinset is the correct term.:thumbsup:

You can use unmodified thinset to install your Durock, but Durock specifies the use of modified thinset for under it and to install all tiles.

Jaz

acfrqflyer 10-24-2008 08:01 PM

thanks jazman,

what is the difference between modified and un-modified??

What would you recommend?

Thaanks again

JazMan 10-24-2008 09:13 PM

I think it's always best to follow the manufacturer's directions. Durock and most other manufacturers want you to use modified so......?

Unmodified is standard thinset. It can be used over most cementitious substrates to install many types of ceramic tiles. It is not used to install tiles to wooden surfaces, which we don't recommend anyway. Modified or polymer modified thinset is used to install practically all types of ceramic tiles including porcelain and glass etc. It gives a much stronger bond and in most cases has some flex to it. ALL backer board manufacturers want us to use modified thinset to install tiles to their boards.

When used under backer boards, modified thinset laminates the two materials together, yet allowing a bit of lateral movement because it's latex/polymer ingredients. I believe this extra bonds makes a more solid substrate. Do you know how to install, fasten, tape the board?

Jaz

acfrqflyer 10-24-2008 10:44 PM

I was going to follow what the manuf. recommends. I never done this before . 1st time. any hints??

Termite 10-24-2008 11:48 PM

Quote:

Originally Posted by JazMan (Post 176219)
First of all, .....because words mean things, thin set mortar should not be referred to as "mud", especially on a tile forum. You do NOT mud the seams and tape them. Mud is sand/cement and is applied an inch thick or so as the base for tile. Thinset is the correct term.:thumbsup:

Oh give me a break. Re-read my post. I used the term mud with quotations around it and then said to use thinset for the application. That is pretty clear, especially to a DIYer. There was no room for confusion in that post, and I realize there is a big difference between mud mix and thinset.

JazMan 10-25-2008 12:04 AM

Hey Termite, you misunderstand my criticism. I know that you know what you're going to use, I'm thinking of all the people that don't know what we're talking about. The industry is full of hacks that say they are going to apply "mud" on certain installations when all they do is spread thin set mortar. I think they just picked up the the term from drywall installers?

So, it makes a difference. There's no comparison between mud and thinset.

Jaz

Bud Cline 10-25-2008 05:23 AM

http://www.contractortalk.com/showthread.php?t=9321

andynicks 11-23-2008 10:50 AM

Hi all,

Thanks for the good information in this post. I found it using Google.

I have a 25sqft floor space in a bathroom I have renovated. I replaced the subfloor with 3/4" OSB and will be laying 12" tile. I purchased modified thin-set mortar on which 1/2" Durock cement board will be installed. Before mixing I read the back of the Versabond thin-set mortar that I picked up at Home Depot. It reads under the heading "Acceptable Surfaces", "Do not bond directly to hardwood, Luan plywood... plastic or OSB panels".

Interesting. I'm on my way over to Lowe's in a few minutes where I will be reading the back of their modified thin-set mortars. Has anyone experienced this same issue?!

Thanks,
Andy

jerryh3 11-23-2008 11:18 AM

Quote:

Originally Posted by andynicks (Post 188977)
Hi all,

Thanks for the good information in this post. I found it using Google.

I have a 25sqft floor space in a bathroom I have renovated. I replaced the subfloor with 3/4" OSB and will be laying 12" tile. I purchased modified thin-set mortar on which 1/2" Durock cement board will be installed. Before mixing I read the back of the Versabond thin-set mortar that I picked up at Home Depot. It reads under the heading "Acceptable Surfaces", "Do not bond directly to hardwood, Luan plywood... plastic or OSB panels".

Interesting. I'm on my way over to Lowe's in a few minutes where I will be reading the back of their modified thin-set mortars. Has anyone experienced this same issue?!

Thanks,
Andy

http://www.custombuildingproducts.co...R=pro\&LANG=en
Is it done? Yes. Will it be covered under warranty if it fails, no. Glue and screw a piece of CDX and you'll be covered. It's one of those things you'll get a lot of different advice about. The schluter install guide shows ditra going over OSB using a latex portland cemnt mortar. There are a few tile guys on here that maybe be able to give you a more definitive answer.


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